{"gene":"MRE11","run_date":"2026-06-10T02:59:51","timeline":{"discoveries":[{"year":1999,"finding":"The Mre11/Rad50/Nbs1 triple complex binds DNA cooperatively and displays enzymatic activities not seen without Nbs1, including partial duplex unwinding and efficient hairpin cleavage; ATP controls a switch in endonuclease specificity allowing cleavage of 3'-protruding strands at double/single-strand transitions; mutational analysis showed Rad50 is responsible for ATP binding but ATP-dependent activities require Nbs1.","method":"In vitro biochemical reconstitution with recombinant proteins; mutational analysis of Rad50 ATP-binding; endonuclease and unwinding assays","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with purified recombinant proteins, mutagenesis, multiple orthogonal enzymatic assays in a single rigorous study","pmids":["10346816"],"is_preprint":false},{"year":2000,"finding":"RAD50, MRE11, and NBS1 associate with TRF2 at human telomeres as demonstrated by nanoelectrospray tandem mass spectrometry and co-immunoprecipitation; NBS1 associates with TRF2 and telomeres specifically in S phase but not G1 or G2; MRE11 and RAD50 are present at interphase telomeres by indirect immunofluorescence.","method":"Nanoelectrospray tandem mass spectrometry; co-immunoprecipitation; indirect immunofluorescence; cell-cycle synchronization","journal":"Nature genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (MS, Co-IP, immunofluorescence) in a single study, cell-cycle-specific association established","pmids":["10888888"],"is_preprint":false},{"year":2001,"finding":"In S. cerevisiae, Tel1 (ATM homolog) and the Mre11 complex define a DNA damage checkpoint pathway that triggers Rad53 activation and its interaction with Rad9 in mitosis, and acts via Rad9/Mek1 in meiosis; the Mre11 complex functions as a damage sensor upstream of Tel1 in this pathway, and the pathway is required for unprocessed DSBs in meiosis.","method":"Genetic epistasis analysis; checkpoint kinase activation assays; yeast genetics","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with defined pathway placement, replicated across mitotic and meiotic contexts","pmids":["11430828"],"is_preprint":false},{"year":2001,"finding":"Xenopus Mre11 complex is required to prevent accumulation of DNA double-strand breaks during chromosomal DNA replication; immunodepletion of X-Mre11 complex from cell-free extracts leads to accumulation of DSBs (detected by TUNEL and γ-H2AX) in replicated DNA; DSBs stimulate phosphorylation and 3′-5′ exonuclease activity of X-Mre11 complex in an ATM-independent manner.","method":"Xenopus egg cell-free extract system; immunodepletion; TUNEL assay; γ-H2AX immunoblotting; exonuclease activity assay","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — functional reconstitution in cell-free extract with immunodepletion, multiple readouts, ATM-independence established by parallel experiment","pmids":["11511367"],"is_preprint":false},{"year":2004,"finding":"Mre11 assembles linear DNA fragments into a high-molecular-weight DNA damage signaling complex that includes MRN, damaged DNA molecules, and activated ATM in Xenopus egg extracts; complex formation requires an intact Mre11 C-terminal domain deleted in some ATLD patients; the ATLD truncation can still perform replication functions of Mre11.","method":"Xenopus egg extract biochemistry; gel filtration/sedimentation; immunoprecipitation; functional complementation with truncation mutants","journal":"PLoS biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — cell-free reconstitution with domain-mapping and functional separation of replication vs. signaling roles","pmids":["15138496"],"is_preprint":false},{"year":2004,"finding":"Nuclear expression of Mre11-Rad50 (but not Nbs1 alone) stimulates ATM activation at early times after low radiation doses; Mre11-Rad50 also acts as an adaptor for ATM-dependent phosphorylation of nibrin and Chk2 but not Smc1; Nbs1's essential nuclear localization role can be uncoupled from its role in ATM activation.","method":"Isogenic cell lines expressing nuclear vs. cytoplasmic MRN components; ATM kinase activation assays; phospho-substrate immunoblotting after irradiation","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — isogenic cell lines with defined nuclear/cytoplasmic separation, multiple substrates, dose-dependent analysis","pmids":["15234984"],"is_preprint":false},{"year":2004,"finding":"The nuclease-deficient mre11-3 (H85L) mutant retains wild-type DNA binding and Rad50/Nbs1 interaction but completely abolishes nuclease activity; crystal structure at 2.3 Å reveals an active-site geometry with wild-type metal-binding environment but inability to hydrolyze DNA, demonstrating structural separation of DNA binding and catalysis.","method":"Crystal structure determination (2.3 Å); in vitro nuclease assays; co-immunoprecipitation; DNA binding assays; IRIF formation assays","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure plus biochemical validation plus cellular assay, mutagenesis with multiple orthogonal readouts","pmids":["15047855"],"is_preprint":false},{"year":2004,"finding":"Werner syndrome protein (WRN) associates with the Mre11 complex via direct binding to Nbs1 in vitro and in vivo; Nbs1 is required for Mre11 complex promotion of WRN helicase activity; WRN co-localizes with the Mre11 complex in response to γ-irradiation or mitomycin C.","method":"Co-immunoprecipitation in vitro and in vivo; siRNA/complementation; co-localization immunofluorescence; helicase activity assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, in vitro binding, functional helicase assay, siRNA rescue, multiple orthogonal methods","pmids":["15026416"],"is_preprint":false},{"year":2005,"finding":"Purified recombinant MRE11/RAD50 cleaves DNA at abasic (AP) sites via an AP-lyase activity conserved from humans to Archaea; cleavage occurs within single-stranded regions of DNA; MRE11 associates specifically with rearranged Ig genes in hypermutating B cells whereas APE1 does not, implicating MRN in the AID/UNG-dependent immunoglobulin gene diversification pathway.","method":"Purified recombinant protein in vitro AP-lyase assay; chromatin immunoprecipitation (ChIP) in hypermutating B cells","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro enzymatic reconstitution with recombinant proteins plus ChIP in relevant cellular context","pmids":["16285919"],"is_preprint":false},{"year":2007,"finding":"Mre11/Rad50 complexes from three organisms catalyze the reversible adenylate kinase reaction in vitro; mutation of the conserved Rad50 signature motif reduces adenylate kinase activity without reducing ATPase; an adenylate kinase inhibitor blocks MR-dependent DNA tethering in vitro and in cell-free extracts; this activity correlates with meiosis and telomere maintenance functions in S. cerevisiae.","method":"In vitro adenylate kinase assays with purified proteins from three organisms; Rad50 mutagenesis; DNA tethering assays; S. cerevisiae genetics","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution across three organisms, mutagenesis, pharmacological inhibition, in vivo genetic validation","pmids":["17349953"],"is_preprint":false},{"year":2008,"finding":"Crystal structure and SAXS analysis of Pyrococcus furiosus Mre11 dimers bound to DNA reveal a four-lobed U-shaped dimer structure critical for MRN complex assembly and DNA end alignment; mutations blocking Mre11 endonuclease activity impair cell survival after DSB induction without affecting MRN complex assembly or Mre11-dependent Ctp1 recruitment.","method":"Crystal structure; SAXS; mutagenesis of fission yeast Mre11; cell survival assays; co-immunoprecipitation","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure plus SAXS plus mutagenesis with functional validation across two organisms","pmids":["18854158"],"is_preprint":false},{"year":2010,"finding":"Mre11-Rad50-Xrs2 (MRX) and Sae2 stimulate 5′-strand resection in a biochemically reconstituted system; degradation of the 5′ strand is catalyzed by Exo1 but is completely dependent on MRX and Sae2 when Exo1 is limiting; stimulation is mainly due to cooperative DNA binding by Exo1, MRX, and Sae2.","method":"Biochemical reconstitution with purified MRX, Sae2, and Exo1; in vitro resection assays; DNA binding assays","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with purified components, mechanistic dissection of stimulation mechanism","pmids":["21102445"],"is_preprint":false},{"year":2010,"finding":"The Mre11-Rad50-Xrs2 (MRX) complex stimulates DNA end resection by the Dna2-Sgs1-RPA machinery by promoting complex formation with Sgs1, which unexpectedly stimulates Sgs1 DNA unwinding activity.","method":"Biochemical reconstitution with purified proteins; in vitro DNA resection and unwinding assays","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with purified components, direct mechanistic test of MRX stimulation of helicase activity","pmids":["20811461"],"is_preprint":false},{"year":2010,"finding":"ATM suppresses DNA end-degradation and microhomology-mediated end joining (MMEJ) in a kinase-activity-dependent manner; Mre11 is the major nuclease responsible for DNA end-degradation and MMEJ in ATM-deficient cells; Mre11 nuclease inhibition (mirin) or knockdown reduces MMEJ repair.","method":"MMEJ reporter assay; Mre11 knockdown; mirin inhibitor; ATM kinase assays; structure-based modeling","journal":"Cell cycle","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional reporter assays, pharmacological and genetic inhibition, single lab","pmids":["20647759"],"is_preprint":false},{"year":2011,"finding":"Mre11 endonuclease nicks the 5′-strand up to 300 nucleotides from the DSB end, enabling bidirectional resection: Exo1 resects 5′→3′ away from the DSB and Mre11 exonuclease resects 3′→5′ toward the DSB end; both exonuclease activities of Mre11 and Exo1 are required for efficient DSB repair in S. cerevisiae.","method":"In vivo physical assays for 5′-end processing in S. cerevisiae meiosis; exo1 and mre11 nuclease mutant analysis; Southern blotting","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal in vivo physical assays in yeast, mechanistic model supported by genetic and molecular readouts","pmids":["22002605"],"is_preprint":false},{"year":2011,"finding":"MRE11 arginine methylation by PRMT1 within its glycine-arginine-rich (GAR) motif is required for DSB end resection and ATR/CHK1 checkpoint signaling; Mre11(RK) knock-in cells (arginines replaced with lysines) show exonuclease and DNA-binding defects in vitro, impaired RPA and RAD51 recruitment, and ATR/CHK1 signaling defects; ATM pathway activation by the M(RK)RN complex is unaffected.","method":"Mouse knock-in allele; in vitro exonuclease and DNA-binding assays; immunofluorescence; immunoblotting for checkpoint kinases; γ-irradiation sensitivity","journal":"Cell research","confidence":"High","confidence_rationale":"Tier 2 / Strong — knock-in mouse model, in vitro biochemistry, multiple pathway readouts, mechanistic separation of ATM vs ATR roles","pmids":["21826105"],"is_preprint":false},{"year":2011,"finding":"Xrs2/Nbs1 is essential for nuclear translocation of Mre11; nuclear localization of Mre11 (Mre11-NLS) bypasses Xrs2 for DNA end resection, meiosis, hairpin resolution, and clastogen resistance; purified MR complex has equivalent activity to MRX in cleavage of protein-blocked DNA ends; Xrs2 is required for Tel1/ATM kinase signaling and NHEJ, acting as a chaperone/adaptor.","method":"Genetic bypass experiments; in vitro reconstitution with purified MR and MRX; yeast genetic assays; Tel1 signaling assays","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution plus genetic epistasis, multiple functional readouts, mechanistic separation of Xrs2-dependent vs. independent functions","pmids":["27746018"],"is_preprint":false},{"year":2013,"finding":"Structure-based design identified specific MRE11 endo- or exonuclease inhibitors; endonuclease inhibition promotes NHEJ over HR at G2 DSBs while exonuclease inhibition confers a repair defect; MRE11 endonuclease initiates resection to license HR, followed by MRE11 exonuclease and EXO1/BLM bidirectional resection; both nuclease activities regulate repair pathway choice.","method":"Structure-based chemical library design; specific nuclease inhibitors; RPA chromatin binding; NHEJ vs. HR repair outcome assays in irradiated G2 cells","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — structure-based inhibitor design, mechanistic dissection of two distinct nuclease activities with specific inhibitors, multiple functional readouts","pmids":["24316220"],"is_preprint":false},{"year":2013,"finding":"MRN-dependent DNA end resection and HR repair can occur independently of H2AX-mediated signaling; the MRN complex promotes DNA end resection and generation of ssDNA critical for HR, and these functions are separable from H2AX-dependent recruitment of 53BP1 and BRCA1.","method":"H2AX-deficient cell lines; HR reporter assays; RPA/ssDNA generation assays; epistasis","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — defined cell lines, functional HR assay, single lab","pmids":["19910469"],"is_preprint":false},{"year":2013,"finding":"Single-molecule FRET reveals that MRN unwinds 15–20 base pairs at the end of a duplex in an ATP-dependent manner; a Rad50 catalytic domain mutant deficient in this ATP-dependent opening is impaired in DNA end resection in vitro and in resection-dependent repair in human cells.","method":"Single-molecule FRET; Rad50 mutagenesis; in vitro resection assay; human cell repair assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Moderate — single-molecule structural visualization plus mutagenesis plus cellular functional validation, multiple orthogonal methods","pmids":["24191051"],"is_preprint":false},{"year":2015,"finding":"Cryo-EM/crystal structure of Methanococcus jannaschii Mre11/Rad50 with ATPγS and DNA reveals that duplex DNA runs symmetrically across the central groove between two ATPγS-bound Rad50 domains; duplex DNA cannot access the Mre11 active site in the ATP-free full-length MR complex; ATP hydrolysis drives rotation of the nucleotide-binding domain and induces DNA melting to allow substrate access to Mre11.","method":"Crystal structure with ATPγS and DNA; in vitro ATPase and nuclease assays; structural comparison of ATP-free vs. ATP-bound states","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure with functional validation, mechanistic ATP hydrolysis-driven conformational model","pmids":["26717941"],"is_preprint":false},{"year":2015,"finding":"Mre11-Sae2 and RPA prevent palindromic gene amplification by processing hairpin-capped DNA ends; loss of Sae2 or the Mre11 nuclease combined with RPA dysfunction increases palindromic duplications ~1,000-fold, indicating that RPA prevents intra-strand annealing and Mre11-Sae2 processes hairpin-capped chromosomes to prevent palindromic duplication.","method":"S. cerevisiae genetics; physical assays for palindromic duplication frequency; epistasis; Mre11 nuclease mutants","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis, quantitative physical assay, multiple mutant combinations, clear mechanistic model","pmids":["26545079"],"is_preprint":false},{"year":2016,"finding":"Cyclin A2 controls Mre11 protein abundance through a C-terminal RNA-binding domain that directly binds Mre11 mRNAs to mediate polysome loading and translation; loss of cyclin A2's ability to upregulate Mre11 in S phase leads to impaired resolution of stalled replication forks and DSB repair.","method":"RNA binding assays; polysome profiling; Mre11 protein quantification in cyclin A2 mutant mice; replication fork analysis; DSB repair assays","journal":"Science","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct RNA binding demonstrated biochemically, polysome loading assay, mouse model with defined phenotype, mechanistic separation of kinase-dependent vs. RNA-binding functions","pmids":["27708105"],"is_preprint":false},{"year":2017,"finding":"GRB2 forms a biophysically validated complex with MRE11; the GRB2-SH2 domain targets the GRB2-MRE11 complex to phosphorylated H2AX at DSBs; GRB2 K109 ubiquitination by RBBP6 releases MRE11 to promote HDR; loss of GRB2 increases MRE11-XRCC1 complex formation and alternative end joining (Alt-EJ).","method":"Co-immunoprecipitation; biophysical binding assays; ubiquitination assay; HR/Alt-EJ reporter assays; RBBP6 depletion; GRB2 knockout","journal":"Science advances","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods, biophysical validation, functional HR/Alt-EJ reporter, mechanistic ubiquitination step identified","pmids":["34348893"],"is_preprint":false},{"year":2017,"finding":"Polo-like kinase 1 (Plk1) phosphorylates Mre11 at serine 649, which primes subsequent CK2-mediated phosphorylation at serine 688; phosphorylation at S649/S688 inhibits loading of the MRN complex to damaged DNA, leading to premature DNA damage checkpoint termination and inhibition of DNA repair.","method":"In vitro kinase assays; phospho-specific antibodies; chromatin loading assays; DNA repair and checkpoint assays; Plk1 and CK2 inhibitors","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro kinase assay, phospho-mutant analysis, chromatin loading assay, single lab","pmids":["28512243"],"is_preprint":false},{"year":2017,"finding":"The Mre11-Nbs1 interaction is essential for viability; a 108-amino-acid Nbs1 fragment comprising the Mre11 interface is sufficient to rescue viability and ATM activation in cultured cells and support hematopoietic differentiation in vivo; most of the Nbs1 protein is dispensable for essential Mre11 complex functions.","method":"TALEN-based genome editing to derive Nbs1mid mice; cell viability and ATM activation assays; in vivo hematopoietic differentiation","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — genome-edited mouse model, defined minimal Nbs1 domain, multiple in vivo and cellular functional readouts","pmids":["28076792"],"is_preprint":false},{"year":2017,"finding":"Single-molecule microscopy shows MRN searches for DNA ends by one-dimensional facilitated diffusion on nucleosome-coated DNA; Rad50 binds homoduplex DNA and promotes diffusion, while Mre11 is required for DNA end recognition and nuclease activities; MRN removes Ku or DNA adducts from occluded ends via an Mre11-dependent nucleolytic reaction; MRN loads Exo1 onto free DNA ends and acts as a processivity factor for Exo1 during long-range resection with RPA.","method":"High-throughput single-molecule microscopy; nucleosome-coated DNA substrates; Mre11 and Rad50 domain-specific mutants; resection assays with RPA and Exo1","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — single-molecule reconstitution, multiple mutants, mechanistic dissection of MRN diffusion/end-recognition/resection roles on physiologically relevant substrates","pmids":["28867292"],"is_preprint":false},{"year":2017,"finding":"MRE11 stability is regulated by CK2-dependent phosphorylation at serines 558/561 and 688/689 of MRE11, which enables binding to the PIH1D1 subunit of the R2TP cochaperone complex; depletion of PIH1D1 causes MRE11 destabilization and impairs MRE11-dependent DNA repair.","method":"Co-immunoprecipitation; CK2 phosphorylation mapping; phospho-mutant stability assays; PIH1D1 depletion; DNA repair assays","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, phospho-mutant, depletion, functional repair assay, single lab","pmids":["28436950"],"is_preprint":false},{"year":2018,"finding":"DYNLL1 directly binds MRE11 in vitro and limits MRE11-dependent DNA end resection in BRCA1-mutant cells; loss of DYNLL1 restores homologous recombination in BRCA1-mutant cells and confers platinum/PARPi resistance.","method":"CRISPR loss-of-function screen; direct in vitro binding assay (DYNLL1–MRE11); end resection assays; HR reporter; drug sensitivity assays","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — CRISPR screen plus direct in vitro binding plus functional end resection and HR assays, multiple orthogonal methods","pmids":["30464262"],"is_preprint":false},{"year":2018,"finding":"GFI1 interacts with PRMT1 and its substrates MRE11 and 53BP1; GFI1 enables PRMT1 to bind and methylate MRE11, which is necessary for MRE11 function in the DNA damage response.","method":"Co-immunoprecipitation; in vitro methylation assays; GFI1 deletion/complementation; DNA damage response assays","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, in vitro methylation assay, functional DDR assay, single lab","pmids":["29651020"],"is_preprint":false},{"year":2019,"finding":"MRE11 is UFMylated at K282 by a UFM1 E3 ligase; UFMylation is required for MRN complex formation under unperturbed conditions and for DSB-induced optimal ATM activation and HR-mediated repair; a pathogenic cancer mutation MRE11(G285C) phenocopies the UFMylation-defective K282R mutant.","method":"UFMylation site mapping; K282R and G285C mutant expression; Co-IP for MRN complex formation; ATM activation assays; HR reporter assay","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — site-specific mutants, complex formation assay, ATM activation, HR reporter, single lab","pmids":["30783677"],"is_preprint":false},{"year":2019,"finding":"Cryo-EM structures of E. coli Mre11-Rad50 homolog SbcCD in resting and DNA-bound cutting states reveal: in the resting state, Mre11 nuclease is blocked by ATP-bound Rad50; upon DNA binding, the two Rad50 coiled coils zip into a rod and together with nucleotide-binding domains clamp around dsDNA; Mre11 moves to the side of Rad50, binds the DNA end, and assembles a DNA cutting channel for nuclease reactions.","method":"Cryo-EM structure determination; biochemical DNA cleavage assays; domain mutagenesis","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — cryo-EM structural determination in two states with mechanistic functional validation","pmids":["31492634"],"is_preprint":false},{"year":2019,"finding":"MRN complex suppresses R-loops and associated DNA damage at transcription-replication conflicts through a non-nucleolytic function of MRE11 that is important for R-loop suppression by the Fanconi Anemia pathway.","method":"Genome-wide trigenic interaction screen in yeast; R-loop detection; genetic epistasis with FA pathway mutants; nuclease-dead Mre11 mutants","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genome-wide screen plus genetic epistasis plus nuclease-dead mutant to define non-nucleolytic function, single lab","pmids":["31537797"],"is_preprint":false},{"year":2021,"finding":"MRE11A deficiency disrupts mitochondrial oxygen consumption and ATP generation in T cells; MRE11A loss causes leakage of mitochondrial DNA (mtDNA) into the cytosol, triggering inflammasome assembly, caspase-1 activation, and pyroptotic cell death; MRE11A overexpression restores mitochondrial fitness and prevents tissue inflammation.","method":"MRE11A knockdown/overexpression; mitochondrial respiration assays; mtDNA cytosolic leakage detection; inflammasome/caspase-1 activation assays; in vivo mouse model","journal":"Cell metabolism","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockdown and overexpression, multiple functional readouts (respiration, mtDNA, caspase-1, inflammation), in vivo validation","pmids":["31327667"],"is_preprint":false},{"year":2022,"finding":"Cryo-EM structure of the eukaryotic Mre11-Rad50-Nbs1 (MRN) complex reveals a 2:2:1 stoichiometry with a single Nbs1 wrapping around the autoinhibited Mre11 nuclease dimer; MRN has two DNA-binding modes (ATP-dependent for loading onto DNA ends and ATP-independent via Mre11 C-terminus); two 60-nm coiled-coil domains form a linear rod joined at zinc-hook apices; two MRN complexes can dimerize via apices to form 120-nm structures.","method":"Cryo-EM structure determination; biochemical DNA binding assays; structural analysis of coiled-coil domain organization","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — cryo-EM structure of eukaryotic MRN with mechanistic functional analysis of two DNA-binding modes","pmids":["36577401"],"is_preprint":false},{"year":2022,"finding":"Cryo-EM structures of SbcCD (bacterial Mre11-Rad50 homolog) bound to a protein-blocked DNA end and a DNA hairpin reveal that Mre11-Rad50 bends internal DNA for endonucleolytic cleavage; the complex is loaded onto blocked DNA ends with Mre11 pointing away from the block, explaining the distinct biochemistries of 3′→5′ exonucleolytic vs. endonucleolytic incision.","method":"Cryo-EM structure determination of two substrate-bound states; biochemical nuclease assays","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — cryo-EM structures in two substrate states with mechanistic explanation of dual nuclease activities","pmids":["35987200"],"is_preprint":false},{"year":2022,"finding":"RNF126 E3 ubiquitin ligase ubiquitinates MRE11 at K339 and K480, increasing its DNA exonuclease activity, subsequent RPA binding, and ATR phosphorylation; RNF126 depletion leads to genomic instability and radiation sensitivity; RNF126 expression is induced by IR via HER2-AKT-NF-κB signaling.","method":"Co-immunoprecipitation; ubiquitination mapping; in vitro exonuclease activity assays; RPA binding; ATR/CHK1 activation assays; RNF126 depletion in cells and mice","journal":"Advanced science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — site-specific ubiquitination mapping, in vitro exonuclease assay, cellular pathway assays, single lab","pmids":["36563124"],"is_preprint":false},{"year":2022,"finding":"PIAS1 promotes MRE11 SUMOylation on chromatin to initiate DNA end resection; SENP3 deSUMOylates MRE11 mainly after it moves away from DSB sites; SENP3 deficiency causes MRE11 accumulation on chromatin and genome instability; SUMOylation protects MRE11 from ubiquitin-mediated degradation at DSB sites.","method":"SUMOylation mapping; PIAS1/SENP3 knockdown; ChIP; ubiquitination assays; DNA end resection assays; cancer mutant analysis","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — site mapping, E3 ligase and protease knockdown, functional resection and stability assays, single lab","pmids":["36050397"],"is_preprint":false},{"year":2022,"finding":"S. cerevisiae Mre11-Rad50 (with or without Xrs2) forms higher-order oligomeric assemblies in solution and on DNA; Rad50 mediates oligomerization; mutations in a conserved Rad50 β-sheet alter oligomerization; MRX oligomerization facilitates foci formation, DNA damage signaling, and repair in vivo; oligomerization drives endonucleolytic cleavage at multiple 5′-strand sites near DSBs without affecting exonuclease activity.","method":"Electron microscopy; biochemical oligomerization assays; Rad50 β-sheet mutagenesis; in vivo foci formation; DNA damage signaling and repair assays; in vitro endonuclease assays","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — EM structural analysis, biochemical assays, mutagenesis, in vivo functional validation, multiple orthogonal methods","pmids":["35501303"],"is_preprint":false},{"year":2022,"finding":"METTL16 interacts with MRE11 through RNA and inhibits MRE11's exonuclease activity in a methyltransferase-independent manner, repressing DNA end resection; upon DNA damage, ATM phosphorylates METTL16 causing conformational change and autoinhibition of its RNA binding, which dissociates the METTL16-RNA-MRE11 complex and releases MRE11.","method":"Co-immunoprecipitation; in vitro exonuclease assays; ATM phosphorylation assays; METTL16 conformational analysis; HR assays","journal":"Nature cancer","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, in vitro exonuclease inhibition assay, ATM phosphorylation mechanistic link, single lab","pmids":["36138131"],"is_preprint":false},{"year":2022,"finding":"PARP14 is a critical co-factor for MRE11 at stalled replication forks in BRCA-deficient cells; PARP14 catalytic activity mediates MRE11 engagement at nascent DNA; KU complex binds reversed forks and protects against EXO1-mediated degradation; KU recruits the PARP14-MRE11 complex, which initiates partial resection to release KU and allow long-range EXO1 resection.","method":"iPOND; chromatin fractionation; PARP14 depletion/inhibition; fork degradation assays (DNA fiber); KU depletion; sequential resection analysis","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple genetic and chemical perturbations, iPOND, fiber assays, epistasis establishing order of events, single lab but multiple orthogonal methods","pmids":["36030235"],"is_preprint":false},{"year":2022,"finding":"POLθ processes stalled Okazaki fragments to suppress ssDNA gaps on lagging strands in the absence of RAD51; inhibition of POLθ allows these fork gaps to be cleaved by the MRE11-NBS1-CtIP endonuclease, producing broken forks with asymmetric single-ended DSBs that impair BRCA2-defective cell survival.","method":"Xenopus laevis biochemistry; electron microscopy visualization of Okazaki fragments; POLθ inhibition; MRE11-NBS1-CtIP depletion; fork structure analysis","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — cell-free reconstitution, direct EM visualization, genetic/chemical perturbations identifying MRE11-NBS1-CtIP as the endonuclease","pmids":["36400008"],"is_preprint":false},{"year":2023,"finding":"MRE11 is lactylated at K673 by the CBP acetyltransferase in response to DNA damage; lactylation is dependent on ATM phosphorylation of CBP; MRE11 lactylation promotes its binding to DNA, facilitating DNA end resection and homologous recombination; inhibition of CBP or LDH reduces MRE11 lactylation, impairing HR.","method":"Site-specific lactylation mapping; CBP acetyltransferase assays; ATM phosphorylation assays; DNA binding assays; HR reporter; cell-penetrating peptide blocking; patient-derived xenograft and organoid models","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — site-specific modification identification, in vitro DNA binding assay, multiple perturbation strategies, in vivo xenograft validation, multiple orthogonal methods","pmids":["38128537"],"is_preprint":false},{"year":2023,"finding":"DYNLL1 is recruited to DSBs by 53BP1 where it limits end resection by binding and disrupting the MRE11 dimer; the Shieldin complex is recruited to DSBs hours after DYNLL1 and its localization depends on MRE11 activity and is regulated by DYNLL1-MRE11 interaction; constitutive DYNLL1-MRE11 association resensitizes Shieldin-loss BRCA1-deficient cells to PARPi.","method":"Co-immunoprecipitation; MRE11 dimer disruption assay; DSB recruitment kinetics; Shieldin localization; PARPi sensitivity assays","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct mechanistic interaction assay, temporal DSB recruitment dynamics, functional PARPi sensitization, multiple orthogonal methods","pmids":["37696958"],"is_preprint":false},{"year":2023,"finding":"ssDNA gaps at stalled replication forks are extended bidirectionally by MRE11 in the 3′→5′ direction and by EXO1 in the 5′→3′ direction; subsequently the parental strand at the ssDNA gap is cleaved by the MRE11 endonuclease to generate a DSB; this process is suppressed by the BRCA pathway.","method":"DNA fiber assays; MRE11 and EXO1 inhibition/depletion; ssDNA gap and DSB detection; BRCA pathway genetic interaction analysis","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — fiber assays, sequential nuclease inhibition, BRCA epistasis, single lab","pmids":["37805499"],"is_preprint":false},{"year":2024,"finding":"The MRE11-RAD50-NBN complex binding to nucleosome fragments is necessary to displace cGAS from acidic-patch-mediated sequestration, enabling cGAS mobilization and activation by dsDNA; MRE11 is therefore essential for cGAS activation in response to oncogenic stress, cytosolic dsDNA, and ionizing radiation; MRE11-dependent cGAS activation promotes ZBP1-RIPK3-MLKL-mediated necroptosis to suppress breast tumorigenesis.","method":"Nucleosome binding assays; cGAS displacement assays; MRE11 depletion/knockout; cGAS activation readouts; necroptosis assays; mouse mammary tumor models","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct nucleosome-MRN binding assay, cGAS displacement demonstrated mechanistically, in vivo tumor suppression validated, multiple orthogonal functional readouts","pmids":["38200309"],"is_preprint":false},{"year":2024,"finding":"UFL1 UFMylates PTIP at K148 upon replication stress; this facilitates PTIP-MLL3/4 complex assembly, H3K4me1/me3 enrichment at stalled forks, and subsequent MRE11 nuclease recruitment to degrade nascent DNA strands; loss of UFL1 or disruption of PTIP UFMylation protects stalled forks from MRE11-mediated degradation and confers PARPi resistance in BRCA1/2-deficient cells.","method":"UFMylation mapping; Co-immunoprecipitation; ChIP for histone marks; DNA fiber assays; MRE11 recruitment assays; UFSP2 overexpression; PARPi sensitivity assays","journal":"Nature chemical biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — site-specific UFMylation, histone mark ChIP, fiber assays, MRE11 recruitment linked mechanistically, single lab","pmids":["38649452"],"is_preprint":false},{"year":2003,"finding":"The Mre11 complex is deposited on chromatin in an S phase-specific manner that is resistant to detergent extraction; it co-localizes extensively with PCNA throughout S phase; chromatin loading is enhanced by replication fork stalling; the complex localizes to ssDNA in hydroxyurea-treated cells; neither DNA damage nor γ-H2AX is required for Mre11 complex chromatin loading in S phase.","method":"Cell synchronization; chromatin fractionation with detergent extraction; co-immunofluorescence with PCNA; hydroxyurea treatment; γ-H2AX immunostaining","journal":"Molecular cancer research : MCR","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — fractionation, co-localization, multiple conditions tested, mechanistic distinction of S-phase vs. damage-induced loading","pmids":["12556560"],"is_preprint":false},{"year":2004,"finding":"RPA and the MRN complex co-localize to discrete foci and physically interact (co-immunoprecipitate) in response to HU- or UV-induced replication fork blockage; both RPA and Mre11 are phosphorylated and accumulate in chromatin-bound fractions upon replication stress; phosphatase treatment abrogates the RPA-MRN co-immunoprecipitation, suggesting phosphorylation mediates the interaction.","method":"Co-immunoprecipitation; chromatin fractionation; immunofluorescence; phosphatase treatment; HU/UV treatment","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, fractionation, phosphatase experiment establishing phosphorylation requirement, single lab","pmids":["15180989"],"is_preprint":false}],"current_model":"MRE11 is the nuclease core of the evolutionarily conserved MRE11-RAD50-NBS1 (MRN) complex, which acts as the primary sensor of DNA double-strand breaks (DSBs) by binding DNA ends through one-dimensional facilitated diffusion, unwinding ~15–20 bp of duplex DNA in an ATP-dependent manner, and assembling a catalytic platform in which Mre11 dimerization and RAD50 ATPase-driven conformational changes regulate both its 3′→5′ exonuclease and endonuclease activities to initiate bidirectional DNA end resection; the endonuclease initiates resection to license homologous recombination (HR) while exonuclease-driven resection commits to HR, with pathway choice regulated by post-translational modifications including PRMT1-mediated arginine methylation of the GAR motif, UFMylation at K282, lactylation at K673 by CBP (ATM-dependent), SUMOylation by PIAS1/SENP3, ubiquitination by RNF126 and CK2/R2TP-dependent stability, and phosphorylation by Plk1/CK2; MRN also directly activates ATM kinase at DSBs (requiring Mre11-Rad50 nuclear presence), associates with telomeres in a cell-cycle-dependent manner via TRF2, suppresses R-loops at transcription-replication conflicts through a non-nucleolytic function, displaces cGAS from nucleosome sequestration to enable innate immune signaling, and maintains mitochondrial genome integrity, with DYNLL1 acting as a direct binding inhibitor of MRE11 dimerization to limit resection extent."},"narrative":{"mechanistic_narrative":"MRE11 is the nuclease core of the conserved MRE11-RAD50-NBS1 (MRN) complex, the primary sensor and processing enzyme for DNA double-strand breaks (DSBs) that initiates end resection to license homologous recombination [PMID:10346816, PMID:22002605, PMID:24316220]. MRN searches for DNA ends by one-dimensional facilitated diffusion on nucleosomal DNA, with RAD50 driving diffusion and MRE11 mediating end recognition and catalysis [PMID:28867292]; ATP binding and hydrolysis by RAD50 drive conformational changes that melt 15-20 bp of duplex and gate substrate access to the otherwise autoinhibited MRE11 nuclease, as resolved in structures of bacterial, archaeal, and eukaryotic complexes [PMID:24191051, PMID:26717941, PMID:31492634, PMID:36577401, PMID:35987200]. MRE11 functions as a U-shaped dimer wrapped by a single NBS1, and end processing proceeds bidirectionally: the MRE11 endonuclease nicks the 5'-strand internal to the break, MRE11 exonuclease resects 3'->5' toward the end, and EXO1/BLM-Sgs1-Dna2 extends resection 5'->3', with MRN acting as a processivity factor and loading these long-range nucleases [PMID:18854158, PMID:22002605, PMID:21102445, PMID:20811461, PMID:28867292]. The two nuclease activities govern repair pathway choice, endonuclease initiating resection toward HR while their balance dictates HR versus NHEJ and microhomology-mediated/alternative end joining [PMID:24316220, PMID:20647759, PMID:34348893]. Beyond resection, MRN directly activates the ATM/Tel1 checkpoint kinase at breaks—a function requiring nuclear MRE11-RAD50—and assembles higher-order signaling complexes on damaged DNA [PMID:11430828, PMID:15234984, PMID:15138496, PMID:35501303]. MRE11 also processes hairpin-capped and palindromic ends, removes blocking adducts and Ku from occluded ends, cleaves abasic sites via an AP-lyase activity, and acts at stalled replication forks where it degrades nascent strands and cleaves ssDNA gaps under BRCA-deficient conditions [PMID:26545079, PMID:28867292, PMID:16285919, PMID:36030235, PMID:37805499, PMID:36400008, PMID:38649452]. The complex associates with telomeres via TRF2 in a cell-cycle-dependent manner [PMID:10888888], suppresses R-loops at transcription-replication conflicts through a non-nucleolytic function [PMID:31537797], maintains mitochondrial genome integrity to prevent mtDNA leakage and inflammasome-driven pyroptosis [PMID:31327667], and displaces cGAS from nucleosome sequestration to enable innate immune signaling and necroptotic tumor suppression [PMID:38200309]. MRE11 activity is extensively tuned by post-translational modifications and binding partners: PRMT1-mediated arginine methylation of the GAR motif (enabled by GFI1), CBP-mediated lactylation at K673, UFMylation at K282, PIAS1/SENP3 SUMOylation, RNF126 ubiquitination, and CK2/Plk1 phosphorylation collectively control DNA binding, complex stability, resection, and checkpoint signaling [PMID:21826105, PMID:29651020, PMID:38128537, PMID:30783677, PMID:36050397, PMID:36563124, PMID:28512243, PMID:28436950], while DYNLL1 directly binds and disrupts the MRE11 dimer to limit resection extent [PMID:30464262, PMID:37696958]. MRE11 protein abundance is further set by cyclin A2, which binds MRE11 mRNA to drive S-phase translation [PMID:27708105]. The C-terminal domain truncated in ataxia-telangiectasia-like disorder (ATLD) is required for DNA damage signaling complex assembly while sparing replication functions [PMID:15138496].","teleology":[{"year":1999,"claim":"Established that MRE11 acquires its full enzymatic repertoire only within the MRN complex, with NBS1 enabling ATP-dependent activities and RAD50 providing the ATP-binding switch.","evidence":"In vitro reconstitution with recombinant proteins, Rad50 ATP-binding mutagenesis, endonuclease and unwinding assays","pmids":["10346816"],"confidence":"High","gaps":["Did not resolve the structural basis of the ATP-driven endonuclease specificity switch","Physiological substrates at breaks not defined"]},{"year":2000,"claim":"Connected MRN to telomere maintenance by showing cell-cycle-regulated association with TRF2 at human telomeres.","evidence":"Tandem MS, co-immunoprecipitation, and immunofluorescence with cell-cycle synchronization","pmids":["10888888"],"confidence":"High","gaps":["Functional consequence of S-phase-specific NBS1-telomere association not established","Nuclease requirement at telomeres untested"]},{"year":2001,"claim":"Placed the MRE11 complex as a DNA damage sensor upstream of the ATM/Tel1 checkpoint kinase and showed it prevents DSB accumulation during replication independently of ATM.","evidence":"Yeast genetic epistasis and checkpoint kinase assays; Xenopus extract immunodepletion with TUNEL/gamma-H2AX readouts","pmids":["11430828","11511367"],"confidence":"High","gaps":["Mechanism by which the complex activates Tel1/ATM not defined","Direct versus indirect role in replication-associated break suppression unresolved"]},{"year":2003,"claim":"Distinguished S-phase replication-coupled chromatin loading of MRN (PCNA-colocalized, damage-independent) from damage-induced recruitment, and linked MRN to stalled-fork ssDNA and RPA.","evidence":"Chromatin fractionation, PCNA co-localization, hydroxyurea/UV treatment, and reciprocal RPA-MRN Co-IP with phosphatase analysis","pmids":["12556560","15180989"],"confidence":"Medium","gaps":["Loading factor for replication-coupled deposition unknown","Functional role at unperturbed forks not separated from damage response"]},{"year":2004,"claim":"Defined that nuclear MRE11-RAD50 directly stimulates ATM activation, structurally separated DNA binding from catalysis, and mapped the ATLD C-terminus to signaling-complex assembly distinct from replication.","evidence":"Isogenic nuclear/cytoplasmic cell lines, nuclease-dead crystal structure at 2.3 A, Xenopus signaling-complex reconstitution, and WRN interaction mapping","pmids":["15234984","15047855","15138496","15026416"],"confidence":"High","gaps":["Direct molecular contacts between MR and ATM not resolved","Whether ATLD signaling defect fully accounts for disease phenotype unclear"]},{"year":2005,"claim":"Broadened MRE11 catalytic scope to AP-lyase activity at abasic sites and implicated it in immunoglobulin gene diversification.","evidence":"In vitro AP-lyase assays with recombinant MRE11/RAD50 and ChIP in hypermutating B cells","pmids":["16285919"],"confidence":"High","gaps":["In vivo contribution to Ig diversification versus DSB repair not separated","Relationship of AP-lyase to canonical endo/exonuclease activities undefined"]},{"year":2007,"claim":"Revealed an unexpected RAD50 adenylate kinase activity coupled to DNA tethering, telomere maintenance, and meiosis.","evidence":"In vitro adenylate kinase assays across three organisms, Rad50 signature-motif mutagenesis, pharmacological inhibition, and yeast genetics","pmids":["17349953"],"confidence":"High","gaps":["How adenylate kinase activity integrates with ATPase-driven resection unclear","Conservation of this function in human cells not tested here"]},{"year":2010,"claim":"Reconstituted MRE11 complex stimulation of long-range resection machineries, showing cooperative DNA binding with Exo1/Sae2 and direct stimulation of the Sgs1 helicase within Dna2-mediated resection.","evidence":"Biochemical reconstitution with purified MRX, Sae2, Exo1, Sgs1, Dna2, and RPA; in vitro resection and unwinding assays","pmids":["21102445","20811461"],"confidence":"High","gaps":["Order of recruitment in cells not established","Did not yet define the endonuclease initiation step"]},{"year":2010,"claim":"Identified MRE11 as the major nuclease driving DNA end degradation and microhomology-mediated end joining when ATM kinase activity is lost.","evidence":"MMEJ reporter assays, Mre11 knockdown, mirin inhibition, and ATM kinase assays","pmids":["20647759"],"confidence":"Medium","gaps":["Single-lab study","Direct demonstration of MRE11 cleavage at MMEJ junctions not shown"]},{"year":2011,"claim":"Resolved the bidirectional resection model in which MRE11 endonuclease nicks internal to the break and MRE11 exonuclease resects toward it while Exo1 resects away, and defined NBS1/Xrs2 as a chaperone for nuclear import and Tel1 signaling.","evidence":"In vivo physical resection assays in yeast meiosis with nuclease mutants; genetic bypass with Mre11-NLS and in vitro MR/MRX reconstitution","pmids":["22002605","27746018"],"confidence":"High","gaps":["Endonuclease incision site selection mechanism not fully defined","Generality of NLS bypass to higher eukaryotes untested"]},{"year":2011,"claim":"Established PRMT1-mediated arginine methylation of the MRE11 GAR motif as a modification required for resection and ATR/CHK1 signaling but not ATM activation.","evidence":"Mre11(RK) knock-in mouse, in vitro exonuclease/DNA-binding assays, and checkpoint immunofluorescence/immunoblotting","pmids":["21826105"],"confidence":"High","gaps":["Stoichiometry and dynamics of methylation in vivo unresolved","How methylation alters DNA binding structurally unknown"]},{"year":2013,"claim":"Pharmacologically separated MRE11 endo- and exonuclease activities, showing endonuclease initiates resection to commit to HR while both activities govern repair pathway choice, independent of H2AX signaling.","evidence":"Structure-based specific nuclease inhibitors, RPA chromatin binding, NHEJ/HR outcome assays in G2 cells, and H2AX-deficient cell HR assays","pmids":["24316220","19910469"],"confidence":"High","gaps":["In vivo selectivity of the inhibitors beyond MRE11 not fully excluded","Coupling of the two nuclease steps temporally not directly visualized"]},{"year":2013,"claim":"Visualized ATP-dependent unwinding of 15-20 bp at duplex ends by MRN and tied this RAD50-driven opening to resection in human cells.","evidence":"Single-molecule FRET, Rad50 catalytic mutagenesis, and in vitro/cellular resection assays","pmids":["24191051"],"confidence":"High","gaps":["Relationship of unwinding to subsequent endonuclease incision not resolved","Behavior on nucleosomal substrates not addressed here"]},{"year":2015,"claim":"Provided the structural mechanism by which ATP hydrolysis rotates the RAD50 nucleotide-binding domain and melts DNA to grant the autoinhibited MRE11 active site substrate access, and defined MRE11's role in preventing palindromic amplification.","evidence":"Crystal structure of archaeal MR with ATPgammaS/DNA plus ATPase/nuclease assays; yeast genetics quantifying palindromic duplications","pmids":["26717941","26545079"],"confidence":"High","gaps":["Eukaryotic NBS1 contribution to the conformational cycle not captured","Hairpin substrate access route only inferred"]},{"year":2016,"claim":"Showed MRE11 abundance is set post-transcriptionally by cyclin A2, which binds MRE11 mRNA to drive S-phase translation needed for fork and DSB repair.","evidence":"RNA binding assays, polysome profiling, cyclin A2 mutant mice, and replication/repair assays","pmids":["27708105"],"confidence":"High","gaps":["Whether cyclin A2 regulates other resection factors similarly unknown","Mechanism of mRNA selectivity not defined"]},{"year":2017,"claim":"Defined single-molecule mechanics of MRN—facilitated diffusion, end recognition, adduct/Ku removal, and Exo1 loading—and structurally constrained the essential MRE11-NBS1 interface to a minimal 108-residue fragment.","evidence":"Single-molecule microscopy on nucleosomal DNA with domain mutants; TALEN-derived Nbs1mid mice with viability/ATM/hematopoiesis readouts","pmids":["28867292","28076792"],"confidence":"High","gaps":["How adduct removal is coupled to ATP cycle not resolved","Functions of the dispensable NBS1 regions not enumerated"]},{"year":2017,"claim":"Identified phosphorylation- and partner-based control of MRN loading and stability through Plk1/CK2 phosphorylation, GRB2 sequestration, and CK2-dependent R2TP/PIH1D1 binding.","evidence":"In vitro kinase assays, chromatin loading assays, GRB2 biophysical binding and HR/Alt-EJ reporters, and PIH1D1 depletion stability assays","pmids":["28512243","34348893","28436950"],"confidence":"Medium","gaps":["Single-lab findings for each modification","Crosstalk among these modifications not integrated"]},{"year":2018,"claim":"Established DYNLL1 as a direct negative regulator that limits MRE11 resection, with loss restoring HR in BRCA1-mutant cells and driving PARPi/platinum resistance, and showed GFI1 licenses PRMT1 methylation of MRE11.","evidence":"CRISPR screen, direct in vitro DYNLL1-MRE11 binding, resection/HR/drug-sensitivity assays; GFI1 Co-IP and in vitro methylation","pmids":["30464262","29651020"],"confidence":"High","gaps":["Structural basis of DYNLL1 inhibition not yet defined (resolved later)","GFI1 study single-lab"]},{"year":2019,"claim":"Expanded MRE11 regulation and biology to UFMylation-dependent complex assembly, a non-nucleolytic R-loop suppression function, structural definition of the DNA-cutting channel, and a mitochondrial role guarding against mtDNA leakage and pyroptosis.","evidence":"UFMylation site mutants with cancer-mutation phenocopy; yeast trigenic screen with nuclease-dead mutants; cryo-EM of bacterial SbcCD; MRE11A knockdown/overexpression with respiration, mtDNA leakage, and caspase-1 assays in vivo","pmids":["30783677","31537797","31492634","31327667"],"confidence":"High","gaps":["Molecular basis of the non-nucleolytic R-loop function unknown","How MRE11 maintains mtDNA integrity mechanistically undefined","UFMylation findings single-lab"]},{"year":2022,"claim":"Delivered the eukaryotic MRN architecture (2:2:1, two DNA-binding modes, oligomerizing coiled-coil rods) and defined fork-associated roles via PARP14 cofactor function, METTL16/RNA-mediated inhibition, and POLtheta-gated MRE11-NBS1-CtIP cleavage of stalled forks.","evidence":"Cryo-EM of eukaryotic MRN and substrate-bound SbcCD; EM oligomerization analysis with Rad50 mutants; iPOND/fiber assays with PARP14 and KU; Xenopus EM of Okazaki fragments; METTL16 Co-IP/exonuclease assays","pmids":["36577401","35987200","35501303","36030235","36400008","36138131","36563124","36050397"],"confidence":"High","gaps":["Functional role of MRN dimerization via zinc-hook apices in cells unclear","Several regulatory inputs (RNF126, PIAS1/SENP3, METTL16) from single labs"]},{"year":2023,"claim":"Defined lactylation at K673 by CBP as an ATM-dependent activating modification, resolved DYNLL1 dimer-disruption mechanism and its 53BP1/Shieldin context, and detailed bidirectional gap extension and endonucleolytic fork cleavage suppressed by BRCA.","evidence":"Site-specific lactylation mapping with PDX/organoid validation; DYNLL1 dimer-disruption and DSB recruitment kinetics; DNA fiber assays with sequential nuclease inhibition","pmids":["38128537","37696958","37805499"],"confidence":"High","gaps":["Interplay of lactylation with other K673-adjacent modifications unknown","Fork-cleavage model partly from single-lab fiber data"]},{"year":2024,"claim":"Established MRE11 as essential for innate immune cGAS activation by displacing cGAS from nucleosome sequestration, driving necroptotic tumor suppression, and linked UFL1-PTIP UFMylation to MRE11 recruitment for fork degradation.","evidence":"Nucleosome binding and cGAS displacement assays with MRE11 knockout, necroptosis readouts, mammary tumor models; UFMylation mapping, histone-mark ChIP, fiber assays","pmids":["38200309","38649452"],"confidence":"High","gaps":["Whether nuclease activity is required for cGAS displacement not fully separated","UFL1-PTIP-MRE11 axis single-lab"]},{"year":null,"claim":"How the dense web of MRE11 post-translational modifications and antagonistic binding partners is hierarchically integrated in real time to set resection length and pathway choice at individual breaks and forks remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model ordering methylation, lactylation, UFMylation, SUMOylation, ubiquitination, and phosphorylation","Structural basis for human MRE11 modification effects on the conformational cycle missing","Quantitative contribution of non-canonical roles (mtDNA, cGAS, R-loops) to organismal phenotypes undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140097","term_label":"catalytic activity, acting on DNA","supporting_discovery_ids":[0,6,14,17,26,31,35]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[0,8,14,17]},{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[6,19,26,34,42]},{"term_id":"GO:0140657","term_label":"ATP-dependent activity","supporting_discovery_ids":[0,19,20]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[5,16]},{"term_id":"GO:0000228","term_label":"nuclear chromosome","supporting_discovery_ids":[47,48,38]},{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[33]}],"pathway":[{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[0,14,17,26]},{"term_id":"R-HSA-69306","term_label":"DNA Replication","supporting_discovery_ids":[3,40,41,44,47]},{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[2,5]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[45,33]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[33,45]}],"complexes":["MRE11-RAD50-NBS1 (MRN)","MRE11-RAD50-Xrs2 (MRX)"],"partners":["RAD50","NBS1","TRF2","WRN","DYNLL1","GRB2","PRMT1","EXO1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P49959","full_name":"Double-strand break repair protein MRE11","aliases":["Meiotic recombination 11 homolog 1","MRE11 homolog 1","Meiotic recombination 11 homolog A","MRE11 homolog A"],"length_aa":708,"mass_kda":80.6,"function":"Core component of the MRN complex, which plays a central role in double-strand break (DSB) repair, DNA recombination, maintenance of telomere integrity and meiosis (PubMed:11741547, PubMed:14657032, PubMed:22078559, PubMed:23080121, PubMed:24316220, PubMed:26240375, PubMed:27889449, PubMed:28867292, PubMed:29670289, PubMed:30464262, PubMed:30612738, PubMed:31353207, PubMed:37696958, PubMed:38128537, PubMed:9590181, PubMed:9651580, PubMed:9705271). The MRN complex is involved in the repair of DNA double-strand breaks (DSBs) via homologous recombination (HR), an error-free mechanism which primarily occurs during S and G2 phases (PubMed:24316220, PubMed:28867292, PubMed:31353207, PubMed:38128537). The complex (1) mediates the end resection of damaged DNA, which generates proper single-stranded DNA, a key initial steps in HR, and is (2) required for the recruitment of other repair factors and efficient activation of ATM and ATR upon DNA damage (PubMed:24316220, PubMed:27889449, PubMed:28867292, PubMed:36050397, PubMed:38128537). Within the MRN complex, MRE11 possesses both single-strand endonuclease activity and double-strand-specific 3'-5' exonuclease activity (PubMed:11741547, PubMed:22078559, PubMed:24316220, PubMed:26240375, PubMed:27889449, PubMed:29670289, PubMed:31353207, PubMed:36563124, PubMed:9590181, PubMed:9651580, PubMed:9705271). After DSBs, MRE11 is loaded onto DSBs sites and cleaves DNA by cooperating with RBBP8/CtIP to initiate end resection (PubMed:27814491, PubMed:27889449, PubMed:30787182). MRE11 first endonucleolytically cleaves the 5' strand at DNA DSB ends to prevent non-homologous end joining (NHEJ) and licence HR (PubMed:24316220). It then generates a single-stranded DNA gap via 3' to 5' exonucleolytic degradation to create entry sites for EXO1- and DNA2-mediated 5' to 3' long-range resection, which is required for single-strand invasion and recombination (PubMed:24316220, PubMed:28867292). RBBP8/CtIP specifically promotes the endonuclease activity of MRE11 to clear protein-DNA adducts and generate clean double-strand break ends (PubMed:27814491, PubMed:27889449, PubMed:30787182). MRE11 endonuclease activity is also enhanced by AGER/RAGE (By similarity). The MRN complex is also required for DNA damage signaling via activation of the ATM and ATR kinases: the nuclease activity of MRE11 is not required to activate ATM and ATR (PubMed:14657032, PubMed:15064416, PubMed:15790808, PubMed:16622404). The MRN complex is also required for the processing of R-loops (PubMed:31537797). The MRN complex is involved in the activation of the cGAS-STING pathway induced by DNA damage during tumorigenesis: the MRN complex acts by displacing CGAS from nucleosome sequestration, thereby activating it (By similarity). In telomeres the MRN complex may modulate t-loop formation (PubMed:10888888) MRE11 contains two DNA-binding domains (DBDs), enabling it to bind both single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA)","subcellular_location":"Nucleus; Chromosome; Chromosome, telomere","url":"https://www.uniprot.org/uniprotkb/P49959/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/MRE11","classification":"Common Essential","n_dependent_lines":722,"n_total_lines":1208,"dependency_fraction":0.597682119205298},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"GAK","stoichiometry":0.2},{"gene":"HIST2H2BE","stoichiometry":0.2},{"gene":"HMGN5","stoichiometry":0.2},{"gene":"NECAP1","stoichiometry":0.2},{"gene":"NUCKS1","stoichiometry":0.2},{"gene":"NUMA1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/MRE11","total_profiled":1310},"omim":[{"mim_id":"617154","title":"MRN COMPLEX-INTERACTING PROTEIN; MRNIP","url":"https://www.omim.org/entry/617154"},{"mim_id":"616940","title":"EXONUCLEASE 3-PRIME-TO-5-PRIME DOMAIN-CONTAINING PROTEIN 2; EXD2","url":"https://www.omim.org/entry/616940"},{"mim_id":"613984","title":"FANCD2 GENE; FANCD2","url":"https://www.omim.org/entry/613984"},{"mim_id":"613899","title":"FANCC GENE; FANCC","url":"https://www.omim.org/entry/613899"},{"mim_id":"613273","title":"INST3- AND NABP-INTERACTING PROTEIN; INIP","url":"https://www.omim.org/entry/613273"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Enhanced","locations":[{"location":"Nucleoplasm","reliability":"Enhanced"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/MRE11"},"hgnc":{"alias_symbol":["ATLD"],"prev_symbol":["MRE11A"]},"alphafold":{"accession":"P49959","domains":[{"cath_id":"3.60.21.10","chopping":"9-299","consensus_level":"high","plddt":94.9495,"start":9,"end":299},{"cath_id":"3.30.110.110","chopping":"306-398","consensus_level":"high","plddt":92.6639,"start":306,"end":398},{"cath_id":"-","chopping":"445-536","consensus_level":"high","plddt":76.9113,"start":445,"end":536}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P49959","model_url":"https://alphafold.ebi.ac.uk/files/AF-P49959-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P49959-F1-predicted_aligned_error_v6.png","plddt_mean":75.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MRE11","jax_strain_url":"https://www.jax.org/strain/search?query=MRE11"},"sequence":{"accession":"P49959","fasta_url":"https://rest.uniprot.org/uniprotkb/P49959.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P49959/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P49959"}},"corpus_meta":[{"pmid":"11988766","id":"PMC_11988766","title":"The Mre11 complex: at the crossroads of dna repair and checkpoint signalling.","date":"2002","source":"Nature reviews. 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Oncology","url":"https://pubmed.ncbi.nlm.nih.gov/24623370","citation_count":37,"is_preprint":false},{"pmid":"35501303","id":"PMC_35501303","title":"Mre11-Rad50 oligomerization promotes DNA double-strand break repair.","date":"2022","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/35501303","citation_count":36,"is_preprint":false},{"pmid":"29917110","id":"PMC_29917110","title":"Perturbing cohesin dynamics drives MRE11 nuclease-dependent replication fork slowing.","date":"2019","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/29917110","citation_count":36,"is_preprint":false},{"pmid":"36050397","id":"PMC_36050397","title":"Crosstalk between SUMOylation and ubiquitylation controls DNA end resection by maintaining MRE11 homeostasis on chromatin.","date":"2022","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/36050397","citation_count":35,"is_preprint":false},{"pmid":"22210882","id":"PMC_22210882","title":"MRE11 and RAD50, but not NBS1, are essential for gene targeting in the moss Physcomitrella patens.","date":"2011","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/22210882","citation_count":35,"is_preprint":false},{"pmid":"34348893","id":"PMC_34348893","title":"GRB2 enforces homology-directed repair initiation by MRE11.","date":"2021","source":"Science advances","url":"https://pubmed.ncbi.nlm.nih.gov/34348893","citation_count":34,"is_preprint":false},{"pmid":"16793391","id":"PMC_16793391","title":"Purification and biochemical characterization of ataxia-telangiectasia mutated and Mre11/Rad50/Nbs1.","date":"2006","source":"Methods in enzymology","url":"https://pubmed.ncbi.nlm.nih.gov/16793391","citation_count":34,"is_preprint":false},{"pmid":"35987200","id":"PMC_35987200","title":"Structural mechanism of endonucleolytic processing of blocked DNA ends and hairpins by Mre11-Rad50.","date":"2022","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/35987200","citation_count":33,"is_preprint":false},{"pmid":"34038735","id":"PMC_34038735","title":"p97/VCP inhibition causes excessive MRE11-dependent DNA end resection promoting cell killing after ionizing radiation.","date":"2021","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/34038735","citation_count":33,"is_preprint":false},{"pmid":"22525466","id":"PMC_22525466","title":"Ataxia-telangiectasia mutated and the Mre11-Rad50-NBS1 complex: promising targets for radiosensitization.","date":"2012","source":"Acta medica Okayama","url":"https://pubmed.ncbi.nlm.nih.gov/22525466","citation_count":31,"is_preprint":false},{"pmid":"32668560","id":"PMC_32668560","title":"A Survey of Reported Disease-Related Mutations in the MRE11-RAD50-NBS1 Complex.","date":"2020","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/32668560","citation_count":30,"is_preprint":false},{"pmid":"34022282","id":"PMC_34022282","title":"MRE11 as a molecular signature and therapeutic target for cancer treatment with radiotherapy.","date":"2021","source":"Cancer letters","url":"https://pubmed.ncbi.nlm.nih.gov/34022282","citation_count":30,"is_preprint":false},{"pmid":"32496651","id":"PMC_32496651","title":"CDC7 kinase promotes MRE11 fork processing, modulating fork speed and chromosomal breakage.","date":"2020","source":"EMBO reports","url":"https://pubmed.ncbi.nlm.nih.gov/32496651","citation_count":28,"is_preprint":false},{"pmid":"38649452","id":"PMC_38649452","title":"UFL1 triggers replication fork degradation by MRE11 in BRCA1/2-deficient cells.","date":"2024","source":"Nature chemical biology","url":"https://pubmed.ncbi.nlm.nih.gov/38649452","citation_count":27,"is_preprint":false},{"pmid":"23755103","id":"PMC_23755103","title":"Sequencing of candidate chromosome instability genes in endometrial cancers reveals somatic mutations in ESCO1, CHTF18, and MRE11A.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23755103","citation_count":27,"is_preprint":false},{"pmid":"37696958","id":"PMC_37696958","title":"Dynamics of the DYNLL1-MRE11 complex regulate DNA end resection and recruitment of Shieldin to DSBs.","date":"2023","source":"Nature structural & molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/37696958","citation_count":26,"is_preprint":false},{"pmid":"31413753","id":"PMC_31413753","title":"Elevated MRE11 expression associated with progression and poor outcome in prostate cancer.","date":"2019","source":"Journal of Cancer","url":"https://pubmed.ncbi.nlm.nih.gov/31413753","citation_count":26,"is_preprint":false},{"pmid":"33927349","id":"PMC_33927349","title":"MRE11 promotes oral cancer progression through RUNX2/CXCR4/AKT/FOXA2 signaling in a nuclease-independent manner.","date":"2021","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/33927349","citation_count":25,"is_preprint":false},{"pmid":"16857186","id":"PMC_16857186","title":"Rad50S alleles of the Mre11 complex: questions answered and questions raised.","date":"2006","source":"Experimental cell research","url":"https://pubmed.ncbi.nlm.nih.gov/16857186","citation_count":24,"is_preprint":false},{"pmid":"26492073","id":"PMC_26492073","title":"Mre11 and Blm-Dependent Formation of ALT-Like Telomeres in Ku-Deficient Ustilago maydis.","date":"2015","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/26492073","citation_count":24,"is_preprint":false},{"pmid":"36892213","id":"PMC_36892213","title":"Mre11-Rad50: the DNA end game.","date":"2023","source":"Biochemical Society transactions","url":"https://pubmed.ncbi.nlm.nih.gov/36892213","citation_count":23,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":44428,"output_tokens":12627,"usd":0.161345,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":24114,"output_tokens":7698,"usd":0.15651,"stage2_stop_reason":"end_turn"},"total_usd":0.317855,"stage1_batch_id":"msgbatch_01BbTCMyrRPyhtEq6b1MdwCN","stage2_batch_id":"msgbatch_011dEed5bbxYvTAaQWKJevxu","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1999,\n      \"finding\": \"The Mre11/Rad50/Nbs1 triple complex binds DNA cooperatively and displays enzymatic activities not seen without Nbs1, including partial duplex unwinding and efficient hairpin cleavage; ATP controls a switch in endonuclease specificity allowing cleavage of 3'-protruding strands at double/single-strand transitions; mutational analysis showed Rad50 is responsible for ATP binding but ATP-dependent activities require Nbs1.\",\n      \"method\": \"In vitro biochemical reconstitution with recombinant proteins; mutational analysis of Rad50 ATP-binding; endonuclease and unwinding assays\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with purified recombinant proteins, mutagenesis, multiple orthogonal enzymatic assays in a single rigorous study\",\n      \"pmids\": [\"10346816\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"RAD50, MRE11, and NBS1 associate with TRF2 at human telomeres as demonstrated by nanoelectrospray tandem mass spectrometry and co-immunoprecipitation; NBS1 associates with TRF2 and telomeres specifically in S phase but not G1 or G2; MRE11 and RAD50 are present at interphase telomeres by indirect immunofluorescence.\",\n      \"method\": \"Nanoelectrospray tandem mass spectrometry; co-immunoprecipitation; indirect immunofluorescence; cell-cycle synchronization\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (MS, Co-IP, immunofluorescence) in a single study, cell-cycle-specific association established\",\n      \"pmids\": [\"10888888\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"In S. cerevisiae, Tel1 (ATM homolog) and the Mre11 complex define a DNA damage checkpoint pathway that triggers Rad53 activation and its interaction with Rad9 in mitosis, and acts via Rad9/Mek1 in meiosis; the Mre11 complex functions as a damage sensor upstream of Tel1 in this pathway, and the pathway is required for unprocessed DSBs in meiosis.\",\n      \"method\": \"Genetic epistasis analysis; checkpoint kinase activation assays; yeast genetics\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with defined pathway placement, replicated across mitotic and meiotic contexts\",\n      \"pmids\": [\"11430828\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Xenopus Mre11 complex is required to prevent accumulation of DNA double-strand breaks during chromosomal DNA replication; immunodepletion of X-Mre11 complex from cell-free extracts leads to accumulation of DSBs (detected by TUNEL and γ-H2AX) in replicated DNA; DSBs stimulate phosphorylation and 3′-5′ exonuclease activity of X-Mre11 complex in an ATM-independent manner.\",\n      \"method\": \"Xenopus egg cell-free extract system; immunodepletion; TUNEL assay; γ-H2AX immunoblotting; exonuclease activity assay\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — functional reconstitution in cell-free extract with immunodepletion, multiple readouts, ATM-independence established by parallel experiment\",\n      \"pmids\": [\"11511367\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Mre11 assembles linear DNA fragments into a high-molecular-weight DNA damage signaling complex that includes MRN, damaged DNA molecules, and activated ATM in Xenopus egg extracts; complex formation requires an intact Mre11 C-terminal domain deleted in some ATLD patients; the ATLD truncation can still perform replication functions of Mre11.\",\n      \"method\": \"Xenopus egg extract biochemistry; gel filtration/sedimentation; immunoprecipitation; functional complementation with truncation mutants\",\n      \"journal\": \"PLoS biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — cell-free reconstitution with domain-mapping and functional separation of replication vs. signaling roles\",\n      \"pmids\": [\"15138496\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Nuclear expression of Mre11-Rad50 (but not Nbs1 alone) stimulates ATM activation at early times after low radiation doses; Mre11-Rad50 also acts as an adaptor for ATM-dependent phosphorylation of nibrin and Chk2 but not Smc1; Nbs1's essential nuclear localization role can be uncoupled from its role in ATM activation.\",\n      \"method\": \"Isogenic cell lines expressing nuclear vs. cytoplasmic MRN components; ATM kinase activation assays; phospho-substrate immunoblotting after irradiation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — isogenic cell lines with defined nuclear/cytoplasmic separation, multiple substrates, dose-dependent analysis\",\n      \"pmids\": [\"15234984\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"The nuclease-deficient mre11-3 (H85L) mutant retains wild-type DNA binding and Rad50/Nbs1 interaction but completely abolishes nuclease activity; crystal structure at 2.3 Å reveals an active-site geometry with wild-type metal-binding environment but inability to hydrolyze DNA, demonstrating structural separation of DNA binding and catalysis.\",\n      \"method\": \"Crystal structure determination (2.3 Å); in vitro nuclease assays; co-immunoprecipitation; DNA binding assays; IRIF formation assays\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure plus biochemical validation plus cellular assay, mutagenesis with multiple orthogonal readouts\",\n      \"pmids\": [\"15047855\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Werner syndrome protein (WRN) associates with the Mre11 complex via direct binding to Nbs1 in vitro and in vivo; Nbs1 is required for Mre11 complex promotion of WRN helicase activity; WRN co-localizes with the Mre11 complex in response to γ-irradiation or mitomycin C.\",\n      \"method\": \"Co-immunoprecipitation in vitro and in vivo; siRNA/complementation; co-localization immunofluorescence; helicase activity assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, in vitro binding, functional helicase assay, siRNA rescue, multiple orthogonal methods\",\n      \"pmids\": [\"15026416\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Purified recombinant MRE11/RAD50 cleaves DNA at abasic (AP) sites via an AP-lyase activity conserved from humans to Archaea; cleavage occurs within single-stranded regions of DNA; MRE11 associates specifically with rearranged Ig genes in hypermutating B cells whereas APE1 does not, implicating MRN in the AID/UNG-dependent immunoglobulin gene diversification pathway.\",\n      \"method\": \"Purified recombinant protein in vitro AP-lyase assay; chromatin immunoprecipitation (ChIP) in hypermutating B cells\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro enzymatic reconstitution with recombinant proteins plus ChIP in relevant cellular context\",\n      \"pmids\": [\"16285919\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Mre11/Rad50 complexes from three organisms catalyze the reversible adenylate kinase reaction in vitro; mutation of the conserved Rad50 signature motif reduces adenylate kinase activity without reducing ATPase; an adenylate kinase inhibitor blocks MR-dependent DNA tethering in vitro and in cell-free extracts; this activity correlates with meiosis and telomere maintenance functions in S. cerevisiae.\",\n      \"method\": \"In vitro adenylate kinase assays with purified proteins from three organisms; Rad50 mutagenesis; DNA tethering assays; S. cerevisiae genetics\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution across three organisms, mutagenesis, pharmacological inhibition, in vivo genetic validation\",\n      \"pmids\": [\"17349953\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Crystal structure and SAXS analysis of Pyrococcus furiosus Mre11 dimers bound to DNA reveal a four-lobed U-shaped dimer structure critical for MRN complex assembly and DNA end alignment; mutations blocking Mre11 endonuclease activity impair cell survival after DSB induction without affecting MRN complex assembly or Mre11-dependent Ctp1 recruitment.\",\n      \"method\": \"Crystal structure; SAXS; mutagenesis of fission yeast Mre11; cell survival assays; co-immunoprecipitation\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure plus SAXS plus mutagenesis with functional validation across two organisms\",\n      \"pmids\": [\"18854158\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Mre11-Rad50-Xrs2 (MRX) and Sae2 stimulate 5′-strand resection in a biochemically reconstituted system; degradation of the 5′ strand is catalyzed by Exo1 but is completely dependent on MRX and Sae2 when Exo1 is limiting; stimulation is mainly due to cooperative DNA binding by Exo1, MRX, and Sae2.\",\n      \"method\": \"Biochemical reconstitution with purified MRX, Sae2, and Exo1; in vitro resection assays; DNA binding assays\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with purified components, mechanistic dissection of stimulation mechanism\",\n      \"pmids\": [\"21102445\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"The Mre11-Rad50-Xrs2 (MRX) complex stimulates DNA end resection by the Dna2-Sgs1-RPA machinery by promoting complex formation with Sgs1, which unexpectedly stimulates Sgs1 DNA unwinding activity.\",\n      \"method\": \"Biochemical reconstitution with purified proteins; in vitro DNA resection and unwinding assays\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with purified components, direct mechanistic test of MRX stimulation of helicase activity\",\n      \"pmids\": [\"20811461\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"ATM suppresses DNA end-degradation and microhomology-mediated end joining (MMEJ) in a kinase-activity-dependent manner; Mre11 is the major nuclease responsible for DNA end-degradation and MMEJ in ATM-deficient cells; Mre11 nuclease inhibition (mirin) or knockdown reduces MMEJ repair.\",\n      \"method\": \"MMEJ reporter assay; Mre11 knockdown; mirin inhibitor; ATM kinase assays; structure-based modeling\",\n      \"journal\": \"Cell cycle\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional reporter assays, pharmacological and genetic inhibition, single lab\",\n      \"pmids\": [\"20647759\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Mre11 endonuclease nicks the 5′-strand up to 300 nucleotides from the DSB end, enabling bidirectional resection: Exo1 resects 5′→3′ away from the DSB and Mre11 exonuclease resects 3′→5′ toward the DSB end; both exonuclease activities of Mre11 and Exo1 are required for efficient DSB repair in S. cerevisiae.\",\n      \"method\": \"In vivo physical assays for 5′-end processing in S. cerevisiae meiosis; exo1 and mre11 nuclease mutant analysis; Southern blotting\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal in vivo physical assays in yeast, mechanistic model supported by genetic and molecular readouts\",\n      \"pmids\": [\"22002605\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"MRE11 arginine methylation by PRMT1 within its glycine-arginine-rich (GAR) motif is required for DSB end resection and ATR/CHK1 checkpoint signaling; Mre11(RK) knock-in cells (arginines replaced with lysines) show exonuclease and DNA-binding defects in vitro, impaired RPA and RAD51 recruitment, and ATR/CHK1 signaling defects; ATM pathway activation by the M(RK)RN complex is unaffected.\",\n      \"method\": \"Mouse knock-in allele; in vitro exonuclease and DNA-binding assays; immunofluorescence; immunoblotting for checkpoint kinases; γ-irradiation sensitivity\",\n      \"journal\": \"Cell research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — knock-in mouse model, in vitro biochemistry, multiple pathway readouts, mechanistic separation of ATM vs ATR roles\",\n      \"pmids\": [\"21826105\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Xrs2/Nbs1 is essential for nuclear translocation of Mre11; nuclear localization of Mre11 (Mre11-NLS) bypasses Xrs2 for DNA end resection, meiosis, hairpin resolution, and clastogen resistance; purified MR complex has equivalent activity to MRX in cleavage of protein-blocked DNA ends; Xrs2 is required for Tel1/ATM kinase signaling and NHEJ, acting as a chaperone/adaptor.\",\n      \"method\": \"Genetic bypass experiments; in vitro reconstitution with purified MR and MRX; yeast genetic assays; Tel1 signaling assays\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution plus genetic epistasis, multiple functional readouts, mechanistic separation of Xrs2-dependent vs. independent functions\",\n      \"pmids\": [\"27746018\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Structure-based design identified specific MRE11 endo- or exonuclease inhibitors; endonuclease inhibition promotes NHEJ over HR at G2 DSBs while exonuclease inhibition confers a repair defect; MRE11 endonuclease initiates resection to license HR, followed by MRE11 exonuclease and EXO1/BLM bidirectional resection; both nuclease activities regulate repair pathway choice.\",\n      \"method\": \"Structure-based chemical library design; specific nuclease inhibitors; RPA chromatin binding; NHEJ vs. HR repair outcome assays in irradiated G2 cells\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — structure-based inhibitor design, mechanistic dissection of two distinct nuclease activities with specific inhibitors, multiple functional readouts\",\n      \"pmids\": [\"24316220\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"MRN-dependent DNA end resection and HR repair can occur independently of H2AX-mediated signaling; the MRN complex promotes DNA end resection and generation of ssDNA critical for HR, and these functions are separable from H2AX-dependent recruitment of 53BP1 and BRCA1.\",\n      \"method\": \"H2AX-deficient cell lines; HR reporter assays; RPA/ssDNA generation assays; epistasis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — defined cell lines, functional HR assay, single lab\",\n      \"pmids\": [\"19910469\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Single-molecule FRET reveals that MRN unwinds 15–20 base pairs at the end of a duplex in an ATP-dependent manner; a Rad50 catalytic domain mutant deficient in this ATP-dependent opening is impaired in DNA end resection in vitro and in resection-dependent repair in human cells.\",\n      \"method\": \"Single-molecule FRET; Rad50 mutagenesis; in vitro resection assay; human cell repair assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — single-molecule structural visualization plus mutagenesis plus cellular functional validation, multiple orthogonal methods\",\n      \"pmids\": [\"24191051\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Cryo-EM/crystal structure of Methanococcus jannaschii Mre11/Rad50 with ATPγS and DNA reveals that duplex DNA runs symmetrically across the central groove between two ATPγS-bound Rad50 domains; duplex DNA cannot access the Mre11 active site in the ATP-free full-length MR complex; ATP hydrolysis drives rotation of the nucleotide-binding domain and induces DNA melting to allow substrate access to Mre11.\",\n      \"method\": \"Crystal structure with ATPγS and DNA; in vitro ATPase and nuclease assays; structural comparison of ATP-free vs. ATP-bound states\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure with functional validation, mechanistic ATP hydrolysis-driven conformational model\",\n      \"pmids\": [\"26717941\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Mre11-Sae2 and RPA prevent palindromic gene amplification by processing hairpin-capped DNA ends; loss of Sae2 or the Mre11 nuclease combined with RPA dysfunction increases palindromic duplications ~1,000-fold, indicating that RPA prevents intra-strand annealing and Mre11-Sae2 processes hairpin-capped chromosomes to prevent palindromic duplication.\",\n      \"method\": \"S. cerevisiae genetics; physical assays for palindromic duplication frequency; epistasis; Mre11 nuclease mutants\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis, quantitative physical assay, multiple mutant combinations, clear mechanistic model\",\n      \"pmids\": [\"26545079\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Cyclin A2 controls Mre11 protein abundance through a C-terminal RNA-binding domain that directly binds Mre11 mRNAs to mediate polysome loading and translation; loss of cyclin A2's ability to upregulate Mre11 in S phase leads to impaired resolution of stalled replication forks and DSB repair.\",\n      \"method\": \"RNA binding assays; polysome profiling; Mre11 protein quantification in cyclin A2 mutant mice; replication fork analysis; DSB repair assays\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct RNA binding demonstrated biochemically, polysome loading assay, mouse model with defined phenotype, mechanistic separation of kinase-dependent vs. RNA-binding functions\",\n      \"pmids\": [\"27708105\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"GRB2 forms a biophysically validated complex with MRE11; the GRB2-SH2 domain targets the GRB2-MRE11 complex to phosphorylated H2AX at DSBs; GRB2 K109 ubiquitination by RBBP6 releases MRE11 to promote HDR; loss of GRB2 increases MRE11-XRCC1 complex formation and alternative end joining (Alt-EJ).\",\n      \"method\": \"Co-immunoprecipitation; biophysical binding assays; ubiquitination assay; HR/Alt-EJ reporter assays; RBBP6 depletion; GRB2 knockout\",\n      \"journal\": \"Science advances\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods, biophysical validation, functional HR/Alt-EJ reporter, mechanistic ubiquitination step identified\",\n      \"pmids\": [\"34348893\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Polo-like kinase 1 (Plk1) phosphorylates Mre11 at serine 649, which primes subsequent CK2-mediated phosphorylation at serine 688; phosphorylation at S649/S688 inhibits loading of the MRN complex to damaged DNA, leading to premature DNA damage checkpoint termination and inhibition of DNA repair.\",\n      \"method\": \"In vitro kinase assays; phospho-specific antibodies; chromatin loading assays; DNA repair and checkpoint assays; Plk1 and CK2 inhibitors\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro kinase assay, phospho-mutant analysis, chromatin loading assay, single lab\",\n      \"pmids\": [\"28512243\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"The Mre11-Nbs1 interaction is essential for viability; a 108-amino-acid Nbs1 fragment comprising the Mre11 interface is sufficient to rescue viability and ATM activation in cultured cells and support hematopoietic differentiation in vivo; most of the Nbs1 protein is dispensable for essential Mre11 complex functions.\",\n      \"method\": \"TALEN-based genome editing to derive Nbs1mid mice; cell viability and ATM activation assays; in vivo hematopoietic differentiation\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genome-edited mouse model, defined minimal Nbs1 domain, multiple in vivo and cellular functional readouts\",\n      \"pmids\": [\"28076792\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Single-molecule microscopy shows MRN searches for DNA ends by one-dimensional facilitated diffusion on nucleosome-coated DNA; Rad50 binds homoduplex DNA and promotes diffusion, while Mre11 is required for DNA end recognition and nuclease activities; MRN removes Ku or DNA adducts from occluded ends via an Mre11-dependent nucleolytic reaction; MRN loads Exo1 onto free DNA ends and acts as a processivity factor for Exo1 during long-range resection with RPA.\",\n      \"method\": \"High-throughput single-molecule microscopy; nucleosome-coated DNA substrates; Mre11 and Rad50 domain-specific mutants; resection assays with RPA and Exo1\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — single-molecule reconstitution, multiple mutants, mechanistic dissection of MRN diffusion/end-recognition/resection roles on physiologically relevant substrates\",\n      \"pmids\": [\"28867292\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"MRE11 stability is regulated by CK2-dependent phosphorylation at serines 558/561 and 688/689 of MRE11, which enables binding to the PIH1D1 subunit of the R2TP cochaperone complex; depletion of PIH1D1 causes MRE11 destabilization and impairs MRE11-dependent DNA repair.\",\n      \"method\": \"Co-immunoprecipitation; CK2 phosphorylation mapping; phospho-mutant stability assays; PIH1D1 depletion; DNA repair assays\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, phospho-mutant, depletion, functional repair assay, single lab\",\n      \"pmids\": [\"28436950\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"DYNLL1 directly binds MRE11 in vitro and limits MRE11-dependent DNA end resection in BRCA1-mutant cells; loss of DYNLL1 restores homologous recombination in BRCA1-mutant cells and confers platinum/PARPi resistance.\",\n      \"method\": \"CRISPR loss-of-function screen; direct in vitro binding assay (DYNLL1–MRE11); end resection assays; HR reporter; drug sensitivity assays\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — CRISPR screen plus direct in vitro binding plus functional end resection and HR assays, multiple orthogonal methods\",\n      \"pmids\": [\"30464262\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"GFI1 interacts with PRMT1 and its substrates MRE11 and 53BP1; GFI1 enables PRMT1 to bind and methylate MRE11, which is necessary for MRE11 function in the DNA damage response.\",\n      \"method\": \"Co-immunoprecipitation; in vitro methylation assays; GFI1 deletion/complementation; DNA damage response assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, in vitro methylation assay, functional DDR assay, single lab\",\n      \"pmids\": [\"29651020\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"MRE11 is UFMylated at K282 by a UFM1 E3 ligase; UFMylation is required for MRN complex formation under unperturbed conditions and for DSB-induced optimal ATM activation and HR-mediated repair; a pathogenic cancer mutation MRE11(G285C) phenocopies the UFMylation-defective K282R mutant.\",\n      \"method\": \"UFMylation site mapping; K282R and G285C mutant expression; Co-IP for MRN complex formation; ATM activation assays; HR reporter assay\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — site-specific mutants, complex formation assay, ATM activation, HR reporter, single lab\",\n      \"pmids\": [\"30783677\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Cryo-EM structures of E. coli Mre11-Rad50 homolog SbcCD in resting and DNA-bound cutting states reveal: in the resting state, Mre11 nuclease is blocked by ATP-bound Rad50; upon DNA binding, the two Rad50 coiled coils zip into a rod and together with nucleotide-binding domains clamp around dsDNA; Mre11 moves to the side of Rad50, binds the DNA end, and assembles a DNA cutting channel for nuclease reactions.\",\n      \"method\": \"Cryo-EM structure determination; biochemical DNA cleavage assays; domain mutagenesis\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — cryo-EM structural determination in two states with mechanistic functional validation\",\n      \"pmids\": [\"31492634\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"MRN complex suppresses R-loops and associated DNA damage at transcription-replication conflicts through a non-nucleolytic function of MRE11 that is important for R-loop suppression by the Fanconi Anemia pathway.\",\n      \"method\": \"Genome-wide trigenic interaction screen in yeast; R-loop detection; genetic epistasis with FA pathway mutants; nuclease-dead Mre11 mutants\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genome-wide screen plus genetic epistasis plus nuclease-dead mutant to define non-nucleolytic function, single lab\",\n      \"pmids\": [\"31537797\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"MRE11A deficiency disrupts mitochondrial oxygen consumption and ATP generation in T cells; MRE11A loss causes leakage of mitochondrial DNA (mtDNA) into the cytosol, triggering inflammasome assembly, caspase-1 activation, and pyroptotic cell death; MRE11A overexpression restores mitochondrial fitness and prevents tissue inflammation.\",\n      \"method\": \"MRE11A knockdown/overexpression; mitochondrial respiration assays; mtDNA cytosolic leakage detection; inflammasome/caspase-1 activation assays; in vivo mouse model\",\n      \"journal\": \"Cell metabolism\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockdown and overexpression, multiple functional readouts (respiration, mtDNA, caspase-1, inflammation), in vivo validation\",\n      \"pmids\": [\"31327667\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Cryo-EM structure of the eukaryotic Mre11-Rad50-Nbs1 (MRN) complex reveals a 2:2:1 stoichiometry with a single Nbs1 wrapping around the autoinhibited Mre11 nuclease dimer; MRN has two DNA-binding modes (ATP-dependent for loading onto DNA ends and ATP-independent via Mre11 C-terminus); two 60-nm coiled-coil domains form a linear rod joined at zinc-hook apices; two MRN complexes can dimerize via apices to form 120-nm structures.\",\n      \"method\": \"Cryo-EM structure determination; biochemical DNA binding assays; structural analysis of coiled-coil domain organization\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — cryo-EM structure of eukaryotic MRN with mechanistic functional analysis of two DNA-binding modes\",\n      \"pmids\": [\"36577401\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Cryo-EM structures of SbcCD (bacterial Mre11-Rad50 homolog) bound to a protein-blocked DNA end and a DNA hairpin reveal that Mre11-Rad50 bends internal DNA for endonucleolytic cleavage; the complex is loaded onto blocked DNA ends with Mre11 pointing away from the block, explaining the distinct biochemistries of 3′→5′ exonucleolytic vs. endonucleolytic incision.\",\n      \"method\": \"Cryo-EM structure determination of two substrate-bound states; biochemical nuclease assays\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — cryo-EM structures in two substrate states with mechanistic explanation of dual nuclease activities\",\n      \"pmids\": [\"35987200\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"RNF126 E3 ubiquitin ligase ubiquitinates MRE11 at K339 and K480, increasing its DNA exonuclease activity, subsequent RPA binding, and ATR phosphorylation; RNF126 depletion leads to genomic instability and radiation sensitivity; RNF126 expression is induced by IR via HER2-AKT-NF-κB signaling.\",\n      \"method\": \"Co-immunoprecipitation; ubiquitination mapping; in vitro exonuclease activity assays; RPA binding; ATR/CHK1 activation assays; RNF126 depletion in cells and mice\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — site-specific ubiquitination mapping, in vitro exonuclease assay, cellular pathway assays, single lab\",\n      \"pmids\": [\"36563124\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"PIAS1 promotes MRE11 SUMOylation on chromatin to initiate DNA end resection; SENP3 deSUMOylates MRE11 mainly after it moves away from DSB sites; SENP3 deficiency causes MRE11 accumulation on chromatin and genome instability; SUMOylation protects MRE11 from ubiquitin-mediated degradation at DSB sites.\",\n      \"method\": \"SUMOylation mapping; PIAS1/SENP3 knockdown; ChIP; ubiquitination assays; DNA end resection assays; cancer mutant analysis\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — site mapping, E3 ligase and protease knockdown, functional resection and stability assays, single lab\",\n      \"pmids\": [\"36050397\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"S. cerevisiae Mre11-Rad50 (with or without Xrs2) forms higher-order oligomeric assemblies in solution and on DNA; Rad50 mediates oligomerization; mutations in a conserved Rad50 β-sheet alter oligomerization; MRX oligomerization facilitates foci formation, DNA damage signaling, and repair in vivo; oligomerization drives endonucleolytic cleavage at multiple 5′-strand sites near DSBs without affecting exonuclease activity.\",\n      \"method\": \"Electron microscopy; biochemical oligomerization assays; Rad50 β-sheet mutagenesis; in vivo foci formation; DNA damage signaling and repair assays; in vitro endonuclease assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — EM structural analysis, biochemical assays, mutagenesis, in vivo functional validation, multiple orthogonal methods\",\n      \"pmids\": [\"35501303\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"METTL16 interacts with MRE11 through RNA and inhibits MRE11's exonuclease activity in a methyltransferase-independent manner, repressing DNA end resection; upon DNA damage, ATM phosphorylates METTL16 causing conformational change and autoinhibition of its RNA binding, which dissociates the METTL16-RNA-MRE11 complex and releases MRE11.\",\n      \"method\": \"Co-immunoprecipitation; in vitro exonuclease assays; ATM phosphorylation assays; METTL16 conformational analysis; HR assays\",\n      \"journal\": \"Nature cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, in vitro exonuclease inhibition assay, ATM phosphorylation mechanistic link, single lab\",\n      \"pmids\": [\"36138131\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"PARP14 is a critical co-factor for MRE11 at stalled replication forks in BRCA-deficient cells; PARP14 catalytic activity mediates MRE11 engagement at nascent DNA; KU complex binds reversed forks and protects against EXO1-mediated degradation; KU recruits the PARP14-MRE11 complex, which initiates partial resection to release KU and allow long-range EXO1 resection.\",\n      \"method\": \"iPOND; chromatin fractionation; PARP14 depletion/inhibition; fork degradation assays (DNA fiber); KU depletion; sequential resection analysis\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple genetic and chemical perturbations, iPOND, fiber assays, epistasis establishing order of events, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"36030235\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"POLθ processes stalled Okazaki fragments to suppress ssDNA gaps on lagging strands in the absence of RAD51; inhibition of POLθ allows these fork gaps to be cleaved by the MRE11-NBS1-CtIP endonuclease, producing broken forks with asymmetric single-ended DSBs that impair BRCA2-defective cell survival.\",\n      \"method\": \"Xenopus laevis biochemistry; electron microscopy visualization of Okazaki fragments; POLθ inhibition; MRE11-NBS1-CtIP depletion; fork structure analysis\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — cell-free reconstitution, direct EM visualization, genetic/chemical perturbations identifying MRE11-NBS1-CtIP as the endonuclease\",\n      \"pmids\": [\"36400008\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"MRE11 is lactylated at K673 by the CBP acetyltransferase in response to DNA damage; lactylation is dependent on ATM phosphorylation of CBP; MRE11 lactylation promotes its binding to DNA, facilitating DNA end resection and homologous recombination; inhibition of CBP or LDH reduces MRE11 lactylation, impairing HR.\",\n      \"method\": \"Site-specific lactylation mapping; CBP acetyltransferase assays; ATM phosphorylation assays; DNA binding assays; HR reporter; cell-penetrating peptide blocking; patient-derived xenograft and organoid models\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — site-specific modification identification, in vitro DNA binding assay, multiple perturbation strategies, in vivo xenograft validation, multiple orthogonal methods\",\n      \"pmids\": [\"38128537\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"DYNLL1 is recruited to DSBs by 53BP1 where it limits end resection by binding and disrupting the MRE11 dimer; the Shieldin complex is recruited to DSBs hours after DYNLL1 and its localization depends on MRE11 activity and is regulated by DYNLL1-MRE11 interaction; constitutive DYNLL1-MRE11 association resensitizes Shieldin-loss BRCA1-deficient cells to PARPi.\",\n      \"method\": \"Co-immunoprecipitation; MRE11 dimer disruption assay; DSB recruitment kinetics; Shieldin localization; PARPi sensitivity assays\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct mechanistic interaction assay, temporal DSB recruitment dynamics, functional PARPi sensitization, multiple orthogonal methods\",\n      \"pmids\": [\"37696958\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"ssDNA gaps at stalled replication forks are extended bidirectionally by MRE11 in the 3′→5′ direction and by EXO1 in the 5′→3′ direction; subsequently the parental strand at the ssDNA gap is cleaved by the MRE11 endonuclease to generate a DSB; this process is suppressed by the BRCA pathway.\",\n      \"method\": \"DNA fiber assays; MRE11 and EXO1 inhibition/depletion; ssDNA gap and DSB detection; BRCA pathway genetic interaction analysis\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — fiber assays, sequential nuclease inhibition, BRCA epistasis, single lab\",\n      \"pmids\": [\"37805499\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"The MRE11-RAD50-NBN complex binding to nucleosome fragments is necessary to displace cGAS from acidic-patch-mediated sequestration, enabling cGAS mobilization and activation by dsDNA; MRE11 is therefore essential for cGAS activation in response to oncogenic stress, cytosolic dsDNA, and ionizing radiation; MRE11-dependent cGAS activation promotes ZBP1-RIPK3-MLKL-mediated necroptosis to suppress breast tumorigenesis.\",\n      \"method\": \"Nucleosome binding assays; cGAS displacement assays; MRE11 depletion/knockout; cGAS activation readouts; necroptosis assays; mouse mammary tumor models\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct nucleosome-MRN binding assay, cGAS displacement demonstrated mechanistically, in vivo tumor suppression validated, multiple orthogonal functional readouts\",\n      \"pmids\": [\"38200309\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"UFL1 UFMylates PTIP at K148 upon replication stress; this facilitates PTIP-MLL3/4 complex assembly, H3K4me1/me3 enrichment at stalled forks, and subsequent MRE11 nuclease recruitment to degrade nascent DNA strands; loss of UFL1 or disruption of PTIP UFMylation protects stalled forks from MRE11-mediated degradation and confers PARPi resistance in BRCA1/2-deficient cells.\",\n      \"method\": \"UFMylation mapping; Co-immunoprecipitation; ChIP for histone marks; DNA fiber assays; MRE11 recruitment assays; UFSP2 overexpression; PARPi sensitivity assays\",\n      \"journal\": \"Nature chemical biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — site-specific UFMylation, histone mark ChIP, fiber assays, MRE11 recruitment linked mechanistically, single lab\",\n      \"pmids\": [\"38649452\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"The Mre11 complex is deposited on chromatin in an S phase-specific manner that is resistant to detergent extraction; it co-localizes extensively with PCNA throughout S phase; chromatin loading is enhanced by replication fork stalling; the complex localizes to ssDNA in hydroxyurea-treated cells; neither DNA damage nor γ-H2AX is required for Mre11 complex chromatin loading in S phase.\",\n      \"method\": \"Cell synchronization; chromatin fractionation with detergent extraction; co-immunofluorescence with PCNA; hydroxyurea treatment; γ-H2AX immunostaining\",\n      \"journal\": \"Molecular cancer research : MCR\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — fractionation, co-localization, multiple conditions tested, mechanistic distinction of S-phase vs. damage-induced loading\",\n      \"pmids\": [\"12556560\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"RPA and the MRN complex co-localize to discrete foci and physically interact (co-immunoprecipitate) in response to HU- or UV-induced replication fork blockage; both RPA and Mre11 are phosphorylated and accumulate in chromatin-bound fractions upon replication stress; phosphatase treatment abrogates the RPA-MRN co-immunoprecipitation, suggesting phosphorylation mediates the interaction.\",\n      \"method\": \"Co-immunoprecipitation; chromatin fractionation; immunofluorescence; phosphatase treatment; HU/UV treatment\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, fractionation, phosphatase experiment establishing phosphorylation requirement, single lab\",\n      \"pmids\": [\"15180989\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MRE11 is the nuclease core of the evolutionarily conserved MRE11-RAD50-NBS1 (MRN) complex, which acts as the primary sensor of DNA double-strand breaks (DSBs) by binding DNA ends through one-dimensional facilitated diffusion, unwinding ~15–20 bp of duplex DNA in an ATP-dependent manner, and assembling a catalytic platform in which Mre11 dimerization and RAD50 ATPase-driven conformational changes regulate both its 3′→5′ exonuclease and endonuclease activities to initiate bidirectional DNA end resection; the endonuclease initiates resection to license homologous recombination (HR) while exonuclease-driven resection commits to HR, with pathway choice regulated by post-translational modifications including PRMT1-mediated arginine methylation of the GAR motif, UFMylation at K282, lactylation at K673 by CBP (ATM-dependent), SUMOylation by PIAS1/SENP3, ubiquitination by RNF126 and CK2/R2TP-dependent stability, and phosphorylation by Plk1/CK2; MRN also directly activates ATM kinase at DSBs (requiring Mre11-Rad50 nuclear presence), associates with telomeres in a cell-cycle-dependent manner via TRF2, suppresses R-loops at transcription-replication conflicts through a non-nucleolytic function, displaces cGAS from nucleosome sequestration to enable innate immune signaling, and maintains mitochondrial genome integrity, with DYNLL1 acting as a direct binding inhibitor of MRE11 dimerization to limit resection extent.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"MRE11 is the nuclease core of the conserved MRE11-RAD50-NBS1 (MRN) complex, the primary sensor and processing enzyme for DNA double-strand breaks (DSBs) that initiates end resection to license homologous recombination [#0, #14, #17]. MRN searches for DNA ends by one-dimensional facilitated diffusion on nucleosomal DNA, with RAD50 driving diffusion and MRE11 mediating end recognition and catalysis [#26]; ATP binding and hydrolysis by RAD50 drive conformational changes that melt 15-20 bp of duplex and gate substrate access to the otherwise autoinhibited MRE11 nuclease, as resolved in structures of bacterial, archaeal, and eukaryotic complexes [#19, #20, #31, #34, #35]. MRE11 functions as a U-shaped dimer wrapped by a single NBS1, and end processing proceeds bidirectionally: the MRE11 endonuclease nicks the 5'-strand internal to the break, MRE11 exonuclease resects 3'->5' toward the end, and EXO1/BLM-Sgs1-Dna2 extends resection 5'->3', with MRN acting as a processivity factor and loading these long-range nucleases [#10, #14, #11, #12, #26]. The two nuclease activities govern repair pathway choice, endonuclease initiating resection toward HR while their balance dictates HR versus NHEJ and microhomology-mediated/alternative end joining [#17, #13, #23]. Beyond resection, MRN directly activates the ATM/Tel1 checkpoint kinase at breaks—a function requiring nuclear MRE11-RAD50—and assembles higher-order signaling complexes on damaged DNA [#2, #5, #4, #38]. MRE11 also processes hairpin-capped and palindromic ends, removes blocking adducts and Ku from occluded ends, cleaves abasic sites via an AP-lyase activity, and acts at stalled replication forks where it degrades nascent strands and cleaves ssDNA gaps under BRCA-deficient conditions [#21, #26, #8, #40, #44, #41, #46]. The complex associates with telomeres via TRF2 in a cell-cycle-dependent manner [#1], suppresses R-loops at transcription-replication conflicts through a non-nucleolytic function [#32], maintains mitochondrial genome integrity to prevent mtDNA leakage and inflammasome-driven pyroptosis [#33], and displaces cGAS from nucleosome sequestration to enable innate immune signaling and necroptotic tumor suppression [#45]. MRE11 activity is extensively tuned by post-translational modifications and binding partners: PRMT1-mediated arginine methylation of the GAR motif (enabled by GFI1), CBP-mediated lactylation at K673, UFMylation at K282, PIAS1/SENP3 SUMOylation, RNF126 ubiquitination, and CK2/Plk1 phosphorylation collectively control DNA binding, complex stability, resection, and checkpoint signaling [#15, #29, #42, #30, #37, #36, #24, #27], while DYNLL1 directly binds and disrupts the MRE11 dimer to limit resection extent [#28, #43]. MRE11 protein abundance is further set by cyclin A2, which binds MRE11 mRNA to drive S-phase translation [#22]. The C-terminal domain truncated in ataxia-telangiectasia-like disorder (ATLD) is required for DNA damage signaling complex assembly while sparing replication functions [#4].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Established that MRE11 acquires its full enzymatic repertoire only within the MRN complex, with NBS1 enabling ATP-dependent activities and RAD50 providing the ATP-binding switch.\",\n      \"evidence\": \"In vitro reconstitution with recombinant proteins, Rad50 ATP-binding mutagenesis, endonuclease and unwinding assays\",\n      \"pmids\": [\"10346816\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve the structural basis of the ATP-driven endonuclease specificity switch\", \"Physiological substrates at breaks not defined\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Connected MRN to telomere maintenance by showing cell-cycle-regulated association with TRF2 at human telomeres.\",\n      \"evidence\": \"Tandem MS, co-immunoprecipitation, and immunofluorescence with cell-cycle synchronization\",\n      \"pmids\": [\"10888888\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of S-phase-specific NBS1-telomere association not established\", \"Nuclease requirement at telomeres untested\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Placed the MRE11 complex as a DNA damage sensor upstream of the ATM/Tel1 checkpoint kinase and showed it prevents DSB accumulation during replication independently of ATM.\",\n      \"evidence\": \"Yeast genetic epistasis and checkpoint kinase assays; Xenopus extract immunodepletion with TUNEL/gamma-H2AX readouts\",\n      \"pmids\": [\"11430828\", \"11511367\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which the complex activates Tel1/ATM not defined\", \"Direct versus indirect role in replication-associated break suppression unresolved\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Distinguished S-phase replication-coupled chromatin loading of MRN (PCNA-colocalized, damage-independent) from damage-induced recruitment, and linked MRN to stalled-fork ssDNA and RPA.\",\n      \"evidence\": \"Chromatin fractionation, PCNA co-localization, hydroxyurea/UV treatment, and reciprocal RPA-MRN Co-IP with phosphatase analysis\",\n      \"pmids\": [\"12556560\", \"15180989\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Loading factor for replication-coupled deposition unknown\", \"Functional role at unperturbed forks not separated from damage response\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Defined that nuclear MRE11-RAD50 directly stimulates ATM activation, structurally separated DNA binding from catalysis, and mapped the ATLD C-terminus to signaling-complex assembly distinct from replication.\",\n      \"evidence\": \"Isogenic nuclear/cytoplasmic cell lines, nuclease-dead crystal structure at 2.3 A, Xenopus signaling-complex reconstitution, and WRN interaction mapping\",\n      \"pmids\": [\"15234984\", \"15047855\", \"15138496\", \"15026416\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct molecular contacts between MR and ATM not resolved\", \"Whether ATLD signaling defect fully accounts for disease phenotype unclear\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Broadened MRE11 catalytic scope to AP-lyase activity at abasic sites and implicated it in immunoglobulin gene diversification.\",\n      \"evidence\": \"In vitro AP-lyase assays with recombinant MRE11/RAD50 and ChIP in hypermutating B cells\",\n      \"pmids\": [\"16285919\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo contribution to Ig diversification versus DSB repair not separated\", \"Relationship of AP-lyase to canonical endo/exonuclease activities undefined\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Revealed an unexpected RAD50 adenylate kinase activity coupled to DNA tethering, telomere maintenance, and meiosis.\",\n      \"evidence\": \"In vitro adenylate kinase assays across three organisms, Rad50 signature-motif mutagenesis, pharmacological inhibition, and yeast genetics\",\n      \"pmids\": [\"17349953\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How adenylate kinase activity integrates with ATPase-driven resection unclear\", \"Conservation of this function in human cells not tested here\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Reconstituted MRE11 complex stimulation of long-range resection machineries, showing cooperative DNA binding with Exo1/Sae2 and direct stimulation of the Sgs1 helicase within Dna2-mediated resection.\",\n      \"evidence\": \"Biochemical reconstitution with purified MRX, Sae2, Exo1, Sgs1, Dna2, and RPA; in vitro resection and unwinding assays\",\n      \"pmids\": [\"21102445\", \"20811461\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Order of recruitment in cells not established\", \"Did not yet define the endonuclease initiation step\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Identified MRE11 as the major nuclease driving DNA end degradation and microhomology-mediated end joining when ATM kinase activity is lost.\",\n      \"evidence\": \"MMEJ reporter assays, Mre11 knockdown, mirin inhibition, and ATM kinase assays\",\n      \"pmids\": [\"20647759\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab study\", \"Direct demonstration of MRE11 cleavage at MMEJ junctions not shown\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Resolved the bidirectional resection model in which MRE11 endonuclease nicks internal to the break and MRE11 exonuclease resects toward it while Exo1 resects away, and defined NBS1/Xrs2 as a chaperone for nuclear import and Tel1 signaling.\",\n      \"evidence\": \"In vivo physical resection assays in yeast meiosis with nuclease mutants; genetic bypass with Mre11-NLS and in vitro MR/MRX reconstitution\",\n      \"pmids\": [\"22002605\", \"27746018\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Endonuclease incision site selection mechanism not fully defined\", \"Generality of NLS bypass to higher eukaryotes untested\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Established PRMT1-mediated arginine methylation of the MRE11 GAR motif as a modification required for resection and ATR/CHK1 signaling but not ATM activation.\",\n      \"evidence\": \"Mre11(RK) knock-in mouse, in vitro exonuclease/DNA-binding assays, and checkpoint immunofluorescence/immunoblotting\",\n      \"pmids\": [\"21826105\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry and dynamics of methylation in vivo unresolved\", \"How methylation alters DNA binding structurally unknown\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Pharmacologically separated MRE11 endo- and exonuclease activities, showing endonuclease initiates resection to commit to HR while both activities govern repair pathway choice, independent of H2AX signaling.\",\n      \"evidence\": \"Structure-based specific nuclease inhibitors, RPA chromatin binding, NHEJ/HR outcome assays in G2 cells, and H2AX-deficient cell HR assays\",\n      \"pmids\": [\"24316220\", \"19910469\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo selectivity of the inhibitors beyond MRE11 not fully excluded\", \"Coupling of the two nuclease steps temporally not directly visualized\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Visualized ATP-dependent unwinding of 15-20 bp at duplex ends by MRN and tied this RAD50-driven opening to resection in human cells.\",\n      \"evidence\": \"Single-molecule FRET, Rad50 catalytic mutagenesis, and in vitro/cellular resection assays\",\n      \"pmids\": [\"24191051\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relationship of unwinding to subsequent endonuclease incision not resolved\", \"Behavior on nucleosomal substrates not addressed here\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Provided the structural mechanism by which ATP hydrolysis rotates the RAD50 nucleotide-binding domain and melts DNA to grant the autoinhibited MRE11 active site substrate access, and defined MRE11's role in preventing palindromic amplification.\",\n      \"evidence\": \"Crystal structure of archaeal MR with ATPgammaS/DNA plus ATPase/nuclease assays; yeast genetics quantifying palindromic duplications\",\n      \"pmids\": [\"26717941\", \"26545079\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Eukaryotic NBS1 contribution to the conformational cycle not captured\", \"Hairpin substrate access route only inferred\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Showed MRE11 abundance is set post-transcriptionally by cyclin A2, which binds MRE11 mRNA to drive S-phase translation needed for fork and DSB repair.\",\n      \"evidence\": \"RNA binding assays, polysome profiling, cyclin A2 mutant mice, and replication/repair assays\",\n      \"pmids\": [\"27708105\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether cyclin A2 regulates other resection factors similarly unknown\", \"Mechanism of mRNA selectivity not defined\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Defined single-molecule mechanics of MRN—facilitated diffusion, end recognition, adduct/Ku removal, and Exo1 loading—and structurally constrained the essential MRE11-NBS1 interface to a minimal 108-residue fragment.\",\n      \"evidence\": \"Single-molecule microscopy on nucleosomal DNA with domain mutants; TALEN-derived Nbs1mid mice with viability/ATM/hematopoiesis readouts\",\n      \"pmids\": [\"28867292\", \"28076792\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How adduct removal is coupled to ATP cycle not resolved\", \"Functions of the dispensable NBS1 regions not enumerated\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Identified phosphorylation- and partner-based control of MRN loading and stability through Plk1/CK2 phosphorylation, GRB2 sequestration, and CK2-dependent R2TP/PIH1D1 binding.\",\n      \"evidence\": \"In vitro kinase assays, chromatin loading assays, GRB2 biophysical binding and HR/Alt-EJ reporters, and PIH1D1 depletion stability assays\",\n      \"pmids\": [\"28512243\", \"34348893\", \"28436950\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab findings for each modification\", \"Crosstalk among these modifications not integrated\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Established DYNLL1 as a direct negative regulator that limits MRE11 resection, with loss restoring HR in BRCA1-mutant cells and driving PARPi/platinum resistance, and showed GFI1 licenses PRMT1 methylation of MRE11.\",\n      \"evidence\": \"CRISPR screen, direct in vitro DYNLL1-MRE11 binding, resection/HR/drug-sensitivity assays; GFI1 Co-IP and in vitro methylation\",\n      \"pmids\": [\"30464262\", \"29651020\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of DYNLL1 inhibition not yet defined (resolved later)\", \"GFI1 study single-lab\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Expanded MRE11 regulation and biology to UFMylation-dependent complex assembly, a non-nucleolytic R-loop suppression function, structural definition of the DNA-cutting channel, and a mitochondrial role guarding against mtDNA leakage and pyroptosis.\",\n      \"evidence\": \"UFMylation site mutants with cancer-mutation phenocopy; yeast trigenic screen with nuclease-dead mutants; cryo-EM of bacterial SbcCD; MRE11A knockdown/overexpression with respiration, mtDNA leakage, and caspase-1 assays in vivo\",\n      \"pmids\": [\"30783677\", \"31537797\", \"31492634\", \"31327667\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of the non-nucleolytic R-loop function unknown\", \"How MRE11 maintains mtDNA integrity mechanistically undefined\", \"UFMylation findings single-lab\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Delivered the eukaryotic MRN architecture (2:2:1, two DNA-binding modes, oligomerizing coiled-coil rods) and defined fork-associated roles via PARP14 cofactor function, METTL16/RNA-mediated inhibition, and POLtheta-gated MRE11-NBS1-CtIP cleavage of stalled forks.\",\n      \"evidence\": \"Cryo-EM of eukaryotic MRN and substrate-bound SbcCD; EM oligomerization analysis with Rad50 mutants; iPOND/fiber assays with PARP14 and KU; Xenopus EM of Okazaki fragments; METTL16 Co-IP/exonuclease assays\",\n      \"pmids\": [\"36577401\", \"35987200\", \"35501303\", \"36030235\", \"36400008\", \"36138131\", \"36563124\", \"36050397\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional role of MRN dimerization via zinc-hook apices in cells unclear\", \"Several regulatory inputs (RNF126, PIAS1/SENP3, METTL16) from single labs\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Defined lactylation at K673 by CBP as an ATM-dependent activating modification, resolved DYNLL1 dimer-disruption mechanism and its 53BP1/Shieldin context, and detailed bidirectional gap extension and endonucleolytic fork cleavage suppressed by BRCA.\",\n      \"evidence\": \"Site-specific lactylation mapping with PDX/organoid validation; DYNLL1 dimer-disruption and DSB recruitment kinetics; DNA fiber assays with sequential nuclease inhibition\",\n      \"pmids\": [\"38128537\", \"37696958\", \"37805499\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Interplay of lactylation with other K673-adjacent modifications unknown\", \"Fork-cleavage model partly from single-lab fiber data\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Established MRE11 as essential for innate immune cGAS activation by displacing cGAS from nucleosome sequestration, driving necroptotic tumor suppression, and linked UFL1-PTIP UFMylation to MRE11 recruitment for fork degradation.\",\n      \"evidence\": \"Nucleosome binding and cGAS displacement assays with MRE11 knockout, necroptosis readouts, mammary tumor models; UFMylation mapping, histone-mark ChIP, fiber assays\",\n      \"pmids\": [\"38200309\", \"38649452\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether nuclease activity is required for cGAS displacement not fully separated\", \"UFL1-PTIP-MRE11 axis single-lab\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the dense web of MRE11 post-translational modifications and antagonistic binding partners is hierarchically integrated in real time to set resection length and pathway choice at individual breaks and forks remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model ordering methylation, lactylation, UFMylation, SUMOylation, ubiquitination, and phosphorylation\", \"Structural basis for human MRE11 modification effects on the conformational cycle missing\", \"Quantitative contribution of non-canonical roles (mtDNA, cGAS, R-loops) to organismal phenotypes undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140097\", \"supporting_discovery_ids\": [0, 6, 14, 17, 26, 31, 35]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0, 8, 14, 17]},\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [6, 19, 26, 34, 42]},\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [0, 19, 20]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [5, 16]},\n      {\"term_id\": \"GO:0000228\", \"supporting_discovery_ids\": [47, 48, 38]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [33]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [0, 14, 17, 26]},\n      {\"term_id\": \"R-HSA-69306\", \"supporting_discovery_ids\": [3, 40, 41, 44, 47]},\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [2, 5]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [45, 33]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [33, 45]}\n    ],\n    \"complexes\": [\"MRE11-RAD50-NBS1 (MRN)\", \"MRE11-RAD50-Xrs2 (MRX)\"],\n    \"partners\": [\"RAD50\", \"NBS1\", \"TRF2\", \"WRN\", \"DYNLL1\", \"GRB2\", \"PRMT1\", \"EXO1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":9,"faith_total":10,"faith_pct":90.0}}