{"gene":"TONSL","run_date":"2026-06-10T10:51:55","timeline":{"discoveries":[{"year":2010,"finding":"TONSL (NFKBIL2) forms a stable heterodimeric complex with MMS22L (C6ORF167). The complex accumulates at regions of ssDNA associated with distressed replication forks or processed DNA breaks, and is required for efficient RAD51 foci formation and homologous recombination-mediated repair of stalled or collapsed replication forks.","method":"Co-immunoprecipitation, RNAi depletion with RAD51 foci assay, camptothecin sensitivity assay, immunofluorescence localization","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — independently replicated across three simultaneous publications (PMIDs 21055983, 21055984, 21055985) using reciprocal Co-IP, localization, and functional RAD51 loading assays","pmids":["21055983","21055984","21055985"],"is_preprint":false},{"year":2010,"finding":"MMS22L-TONSL (NFKBIL2) interacts with the FACT (facilitator of chromatin transcription) and MCM (minichromosome maintenance) complexes, and TONSL co-purifies with histones and multiple chromatin remodelling and DNA replication/repair factors.","method":"Mass spectrometry-based affinity purification, co-immunoprecipitation","journal":"Molecular cell / The EMBO journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — identified by AP-MS in two independent studies but full reciprocal validation not described in abstracts","pmids":["21055985","21113133"],"is_preprint":false},{"year":2010,"finding":"Loss of MMS22L-TONSL results in S phase-dependent spontaneous DNA double-strand breaks, checkpoint activation, and inability to complete DNA synthesis after replication fork collapse, placing the complex at replication forks as a genome caretaker.","method":"RNAi knockdown, γH2AX foci assay, cell cycle analysis, live-cell imaging-based RNAi screen","journal":"Molecular cell / The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — replicated in multiple independent labs with consistent phenotypic readouts (DSBs, checkpoint activation, fork collapse)","pmids":["21055983","21055984","21055985","21113133"],"is_preprint":false},{"year":2016,"finding":"The TONSL ankyrin repeat domain (ARD) functions as a reader of histone H4 tails unmethylated at K20 (H4K20me0), a mark specific to newly incorporated histones post-replication. This interaction recruits TONSL-MMS22L to post-replicative chromatin and is required for TONSL-MMS22L binding to chromatin and accumulation at challenged replication forks and DNA lesions. TONSL ARD mutants are toxic, compromising genome stability and cell viability.","method":"Histone peptide pulldown, domain mapping/mutagenesis of TONSL ARD, chromatin fractionation, cell cycle analysis (H4K20me0 dynamics), replication fork accumulation assay, viability assay with ARD mutants","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro peptide binding assay with mutagenesis, structural domain identification, multiple orthogonal functional validations in one rigorous study","pmids":["27338793"],"is_preprint":false},{"year":2016,"finding":"The MMS22L subunit of the MMS22L-TONSL heterodimer directly interacts with RAD51 and limits RAD51 assembly on dsDNA, thereby stimulating RAD51-ssDNA nucleoprotein filament formation and RAD51-dependent strand exchange activity in vitro. MMS22L-TONSL also associates with RPA-coated ssDNA at replication forks and promotes replication fork reversal and HR-mediated restart of stalled forks in vivo.","method":"In vitro RAD51 strand exchange assay with recombinant MMS22L-TONSL, Co-IP for RAD51 interaction, iPOND for replication fork localization, cell-based HR assay with MMS22L RAD51-interaction mutant","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with recombinant protein plus mutagenesis and in vivo functional validation in one study","pmids":["27797818"],"is_preprint":false},{"year":2018,"finding":"Recruitment of MMS22L-TONSL to ssDNA during homologous recombination depends on the histone chaperones ASF1 and CAF-1. Knockdown of ASF1 or CAF-1, or a mutation preventing ASF1A binding to histones, reduces MMS22L-TONSL recruitment and impairs RAD51 loading onto ssDNA, resulting in persistent RPA foci, extensive DNA end resection, persistent ATR-Chk1 activation, and cell cycle arrest. Additionally, DNA-PKcs-dependent phosphorylation of ASF1A upon DNA damage enhances chromatin assembly and promotes MMS22L-TONSL recruitment.","method":"RNAi knockdown of ASF1/CAF-1, ASF1A phosphorylation assay, RAD51 and RPA foci assay, cell cycle analysis, DNA end resection assay, co-immunoprecipitation","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (knockdown, phospho-mutant, foci assays, cell cycle) in a single rigorous study establishing pathway position","pmids":["29478807"],"is_preprint":false},{"year":2022,"finding":"MMS22L-TONSL functions in sister chromatid cohesion (SCC) establishment in a pathway parallel to DSCC1-RFC. Synthetic lethality between DSCC1 and MMS22L loss results from detrimental SCC loss. MMS22L-TONSL and DSCC1-RFC both facilitate ESCO2 recruitment to replication forks, suggesting that distinct ESCO2 recruitment pathways promote SCC establishment.","method":"Genome-wide CRISPR synthetic lethality screen in DSCC1-KO cells, SCC assays, epistasis analysis, ESCO2 recruitment assay","journal":"Life science alliance","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — CRISPR screen with epistasis and ESCO2 recruitment follow-up, single lab","pmids":["36622344"],"is_preprint":false},{"year":2019,"finding":"Hypomorphic bi-allelic loss-of-function variants in TONSL cause SPONASTRIME dysplasia; subject-derived cell lines exhibit increased spontaneous replication fork stalling, chromosomal aberrations, and reduced CPT-induced RAD51 foci, all rescued by re-expression of wild-type TONSL. Tonsl-/- mice show early embryonic lethality and tonsl-/- zebrafish show reduced length, spinal abnormalities, and early lethality.","method":"Whole-exome sequencing, rescue experiment (WT TONSL re-expression), DNA fiber assay, chromosomal aberration analysis, RAD51 foci assay, mouse/zebrafish knockout models","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — independently replicated in two simultaneous papers with rescue experiments, animal models, and multiple cellular assays","pmids":["30773277","30773278"],"is_preprint":false},{"year":2023,"finding":"TONSL overexpression alone immortalizes primary breast epithelial cells, increases telomerase activity, and increases chromatin accessibility to pro-oncogenic transcription factors including NF-κB while limiting access to p53. TONSL-overexpressing cells are sensitive to the TONSL-FACT complex inhibitor CBL0137.","method":"hTERT-immortalization comparison transcriptomics, primary breast cell immortalization assay, ATAC-seq for chromatin accessibility, in vivo tumor formation, CBL0137 sensitivity assay","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (chromatin accessibility, immortalization assay, drug sensitivity) in single lab study","pmids":["37057595"],"is_preprint":false},{"year":2025,"finding":"TONSL-MMS22L and FANCM form an interdependent complex on chromatin upon replication stress. TONSL-MMS22L recruits FANCM and the FA core complex to stalled and collapsed forks, maintains FANCM on stressed chromatin, promotes FANCD2 monoubiquitination, and facilitates both HR-mediated repair and replication traverse of DNA interstrand crosslinks. Reciprocally, FANCM DNA translocase activity and FANCM phosphorylation facilitate recruitment of TONSL-MMS22L and RAD51 to perturbed forks.","method":"Co-immunoprecipitation, chromatin fractionation, FANCD2 ubiquitination assay, ICL repair assay, replication traverse assay, phosphorylation mutant analysis","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple biochemical and functional assays in a single preprint lab study, not yet peer-reviewed","pmids":["41030968"],"is_preprint":true},{"year":2026,"finding":"TONSL suppresses tandem duplication (TD) formation dependent on polymerase theta-mediated end joining (TMEJ). Loss of TONSL (tnsl-1) in C. elegans results in accumulation of TDs in two distinct size classes (~25 kb and ~300 kb) arising in different developmental contexts; both classes require polymerase theta. Inhibition of break-induced replication (BIR) via Pif1 helicase loss reduces TD size. The same TD signature is seen in TONSL-deficient Arabidopsis, demonstrating evolutionary conservation.","method":"C. elegans tnsl-1 knockout, whole-genome sequencing for TD detection, genetic epistasis with polymerase theta and Pif1 mutants, Arabidopsis TONSL knockout","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with multiple mutants across two organisms, whole-genome sequencing readout, mechanistic pathway placement","pmids":["41896213"],"is_preprint":false},{"year":2024,"finding":"The MMS22L-TONSL complex interacts with FIGNL1 (an anti-recombinase that dissociates RAD51 filaments) and is critical for HR in BRCA2/FIGNL1 double-deficient cells, positioning TONSL-MMS22L in a pathway that regulates RAD51 activity downstream of BRCA2.","method":"Co-immunoprecipitation, BRCA2/FIGNL1 double-deficient cell viability and HR assay, RAD51 foci analysis","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single preprint, TONSL-MMS22L interaction with FIGNL1 is a secondary finding described only briefly in the abstract","pmids":["bio_10.1101_2024.11.03.621741"],"is_preprint":true},{"year":2026,"finding":"Loss of TONSL in HCC cells impairs RAD51 recruitment to DNA damage sites, resulting in defective homologous recombination repair and enhanced apoptosis. TONSL-knockout HCC cells show increased sensitivity to PARP inhibitors and reduced xenograft tumor growth.","method":"TONSL knockout (CRISPR), RAD51 foci assay, HR repair assay, PARP inhibitor sensitivity assay, xenograft model","journal":"Cancer science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct KO with multiple orthogonal functional readouts (RAD51 foci, HR assay, PARP inhibitor sensitivity, in vivo), single lab","pmids":["42037569"],"is_preprint":false},{"year":2000,"finding":"The TONSL gene (NFKBIL2/IkappaBR) was cloned and characterized; revised mRNA and protein sequence predicted a larger protein than originally described. The gene was mapped to chromosome 8q24.3. The ankyrin-repeat region of TONSL has intron-exon junction positions different from other IkappaBs, indicating it is not a canonical IkappaB family member.","method":"cDNA cloning, genomic sequencing, PCR-based somatic cell hybrid panel, FISH mapping","journal":"Annals of human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct molecular characterization by cloning and chromosomal mapping, single lab","pmids":["11246458"],"is_preprint":false}],"current_model":"TONSL is a multi-domain scaffold protein that forms a stable heterodimer with MMS22L; its ankyrin repeat domain reads H4K20me0 on newly deposited histones to target the complex to post-replicative chromatin, where MMS22L directly interacts with RAD51 to stimulate ssDNA nucleofilament formation and strand exchange, suppress dsDNA-bound RAD51, promote replication fork reversal, establish sister chromatid cohesion via an ESCO2 recruitment pathway, recruit FANCM and the FA core complex for interstrand crosslink repair, suppress polymerase-theta-dependent tandem duplications, and depend on histone chaperones ASF1/CAF-1 for its own recruitment to ssDNA during homologous recombination."},"narrative":{"mechanistic_narrative":"TONSL is a multi-domain scaffold protein that operates as a genome caretaker at replication forks, where it forms a stable heterodimer with MMS22L that accumulates at ssDNA generated by distressed forks or processed breaks and is required for efficient RAD51 focus formation and homologous-recombination-mediated repair [PMID:21055983, PMID:21055984, PMID:21055985, PMID:21113133]. The complex is targeted to post-replicative chromatin through the TONSL ankyrin-repeat domain, which reads histone H4 unmethylated at K20 (H4K20me0), a mark restricted to newly deposited histones [PMID:27338793]. Within the heterodimer the MMS22L subunit directly binds RAD51, suppresses unproductive RAD51 assembly on dsDNA, and stimulates RAD51-ssDNA nucleofilament formation and strand exchange, while the complex associates with RPA-coated ssDNA to promote fork reversal and HR-mediated restart [PMID:27797818]. Recruitment of MMS22L-TONSL to ssDNA depends on the histone chaperones ASF1 and CAF-1, with DNA-PKcs-dependent ASF1A phosphorylation enhancing its loading after damage [PMID:29478807]. Beyond canonical HR, TONSL-MMS22L contributes to sister chromatid cohesion via an ESCO2 recruitment pathway parallel to DSCC1-RFC [PMID:36622344], recruits FANCM and the FA core complex to drive interstrand-crosslink repair and fork traverse [PMID:41030968], and suppresses polymerase-theta-dependent tandem duplications, a function conserved across worms and plants [PMID:41896213]. Hypomorphic bi-allelic loss-of-function variants in TONSL cause SPONASTRIME dysplasia, with patient cells showing fork stalling, chromosomal aberrations, and reduced RAD51 foci that are rescued by wild-type TONSL [PMID:30773277, PMID:30773278]. TONSL overexpression immortalizes primary breast epithelial cells and remodels chromatin accessibility toward pro-oncogenic factors, and TONSL loss confers PARP-inhibitor sensitivity, linking the gene to tumorigenesis and synthetic-lethal vulnerability [PMID:37057595, PMID:42037569].","teleology":[{"year":2000,"claim":"Before any DNA-repair role was known, the gene had to be defined at the molecular level; cloning established TONSL/NFKBIL2 as a distinct ankyrin-repeat protein rather than a canonical IkappaB family member.","evidence":"cDNA cloning, genomic sequencing, and FISH mapping to chromosome 8q24.3","pmids":["11246458"],"confidence":"Medium","gaps":["No functional role assigned at this stage","Ankyrin-repeat function uncharacterized"]},{"year":2010,"claim":"The central question of what TONSL does was answered by identifying its stable partner MMS22L and placing the heterodimer at ssDNA on distressed forks, where it is required for RAD51 loading and HR repair.","evidence":"Co-IP, RNAi depletion with RAD51 foci and camptothecin sensitivity assays, immunofluorescence across three simultaneous studies plus a fourth","pmids":["21055983","21055984","21055985","21113133"],"confidence":"High","gaps":["Mechanism of RAD51 stimulation not yet resolved","Mode of chromatin targeting unknown"]},{"year":2010,"claim":"To connect the complex to chromatin machinery, AP-MS identified FACT, MCM, and histone associations, hinting that the complex acts in a replication/chromatin context.","evidence":"Mass spectrometry-based affinity purification and Co-IP in two independent studies","pmids":["21055985","21113133"],"confidence":"Medium","gaps":["Direct vs indirect interactions not distinguished","Functional significance of FACT/MCM binding untested here"]},{"year":2016,"claim":"The unresolved targeting mechanism was solved by showing the TONSL ankyrin-repeat domain reads H4K20me0, explaining how the complex is restricted to newly replicated chromatin.","evidence":"Histone peptide pulldown, ARD mutagenesis, chromatin fractionation, fork-accumulation and viability assays","pmids":["27338793"],"confidence":"High","gaps":["Structural basis of ARD-H4K20me0 recognition not fully detailed","Coupling between reading and RAD51 loading unclear"]},{"year":2016,"claim":"The biochemical basis of RAD51 stimulation was established by showing MMS22L directly binds RAD51, suppresses dsDNA-bound RAD51, and promotes ssDNA filament formation and fork reversal.","evidence":"In vitro strand-exchange assay with recombinant MMS22L-TONSL, Co-IP, iPOND, and HR assay with interaction mutant","pmids":["27797818"],"confidence":"High","gaps":["TONSL subunit's catalytic contribution to filament formation not defined","Regulation of dsDNA suppression in vivo unclear"]},{"year":2018,"claim":"How the complex reaches ssDNA was clarified by placing histone chaperones ASF1/CAF-1 upstream of its recruitment and linking DNA-PKcs phosphorylation of ASF1A to enhanced loading.","evidence":"RNAi of ASF1/CAF-1, ASF1A phospho-mutant, RAD51/RPA foci, resection and cell-cycle assays","pmids":["29478807"],"confidence":"High","gaps":["Direct chaperone-TONSL contacts not mapped","Order of chaperone and H4K20me0 engagement unresolved"]},{"year":2019,"claim":"The physiological and disease relevance was established by showing hypomorphic TONSL variants cause SPONASTRIME dysplasia with fork-stalling phenotypes rescued by wild-type protein, and that loss is lethal in mice and zebrafish.","evidence":"Whole-exome sequencing, WT rescue, DNA fiber and RAD51 foci assays, mouse and zebrafish knockouts in two simultaneous papers","pmids":["30773277","30773278"],"confidence":"High","gaps":["How replication defects translate to skeletal dysplasia unclear","Tissue-specific requirements undefined"]},{"year":2022,"claim":"A role beyond HR was uncovered by linking TONSL-MMS22L to sister chromatid cohesion via ESCO2 recruitment in a pathway parallel to DSCC1-RFC.","evidence":"Genome-wide CRISPR synthetic-lethality screen in DSCC1-KO cells, SCC and ESCO2 recruitment assays, epistasis","pmids":["36622344"],"confidence":"Medium","gaps":["Mechanism of ESCO2 recruitment by the complex unknown","Single-lab finding"]},{"year":2023,"claim":"An oncogenic dimension was identified by showing TONSL overexpression immortalizes breast epithelial cells and reshapes chromatin accessibility, with sensitivity to a TONSL-FACT inhibitor.","evidence":"Immortalization assay, ATAC-seq, in vivo tumor formation, CBL0137 sensitivity","pmids":["37057595"],"confidence":"Medium","gaps":["Direct chromatin targets of TONSL in transformation undefined","Mechanistic link between FACT and accessibility changes unclear"]},{"year":2025,"claim":"The complex was integrated into the Fanconi anemia ICL-repair network by showing an interdependent TONSL-MMS22L/FANCM relationship that promotes FANCD2 monoubiquitination and fork traverse.","evidence":"Co-IP, chromatin fractionation, FANCD2 ubiquitination, ICL repair and traverse assays, phospho-mutant analysis (preprint)","pmids":["41030968"],"confidence":"Medium","gaps":["Not yet peer-reviewed","Direct vs indirect FANCM contact not fully resolved"]},{"year":2026,"claim":"A conserved mutational-suppression role was demonstrated by showing TONSL loss causes polymerase-theta-dependent tandem duplications across worm and plant systems.","evidence":"C. elegans and Arabidopsis knockouts, whole-genome sequencing of TDs, epistasis with polymerase theta and Pif1","pmids":["41896213"],"confidence":"High","gaps":["Direct molecular step at which TONSL blocks TMEJ undefined","Human relevance not directly tested"]},{"year":2026,"claim":"Therapeutic vulnerability was shown by demonstrating that TONSL loss impairs RAD51 recruitment in HCC, sensitizing cells to PARP inhibitors and reducing tumor growth.","evidence":"CRISPR knockout, RAD51 foci and HR assays, PARP inhibitor sensitivity, xenograft model","pmids":["42037569"],"confidence":"Medium","gaps":["Generalizability across tumor types untested","Single-lab finding"]},{"year":null,"claim":"How the multiple TONSL-MMS22L functions—RAD51 loading, cohesion, ICL repair, and TD suppression—are coordinated and switched at a single fork remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of the full heterodimer on chromatin","Unclear how distinct downstream pathways are partitioned","FIGNL1 interaction remains a single low-confidence preprint observation"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0042393","term_label":"histone binding","supporting_discovery_ids":[3]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,4]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[4]}],"localization":[{"term_id":"GO:0000228","term_label":"nuclear chromosome","supporting_discovery_ids":[3,5]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,2]}],"pathway":[{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[0,4,9]},{"term_id":"R-HSA-69306","term_label":"DNA Replication","supporting_discovery_ids":[2,4]},{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[3,8]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[6]}],"complexes":["MMS22L-TONSL heterodimer"],"partners":["MMS22L","RAD51","ASF1","CAF-1","FANCM","ESCO2","FIGNL1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q96HA7","full_name":"Tonsoku-like protein","aliases":["Inhibitor of kappa B-related protein","I-kappa-B-related protein","IkappaBR","NF-kappa-B inhibitor-like protein 2","Nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor-like 2"],"length_aa":1378,"mass_kda":150.9,"function":"Component of the MMS22L-TONSL complex, a complex that promotes homologous recombination-mediated repair of double-strand breaks (DSBs) at stalled or collapsed replication forks (PubMed:21055983, PubMed:21055984, PubMed:21055985, PubMed:21113133, PubMed:26527279, PubMed:27338793, PubMed:27797818, PubMed:29478807, PubMed:30773278). The MMS22L-TONSL complex is required to maintain genome integrity during DNA replication (PubMed:21055983, PubMed:21055984, PubMed:21055985). It mediates the assembly of RAD51 filaments on single-stranded DNA (ssDNA): the MMS22L-TONSL complex is recruited to DSBs following histone replacement by histone chaperones and eviction of the replication protein A complex (RPA/RP-A) from DSBs (PubMed:21055983, PubMed:21055984, PubMed:21055985, PubMed:27797818, PubMed:29478807). Following recruitment to DSBs, the TONSL-MMS22L complex promotes recruitment of RAD51 filaments and subsequent homologous recombination (PubMed:27797818, PubMed:29478807). Within the complex, TONSL acts as a histone reader, which recognizes and binds newly synthesized histones following their replacement by histone chaperones (PubMed:27338793, PubMed:29478807). Specifically binds histone H4 lacking methylation at 'Lys-20' (H4K20me0) and histone H3.1 (PubMed:27338793)","subcellular_location":"Nucleus; Chromosome; Cytoplasm","url":"https://www.uniprot.org/uniprotkb/Q96HA7/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/TONSL","classification":"Common Essential","n_dependent_lines":1203,"n_total_lines":1208,"dependency_fraction":0.9958609271523179},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"OST4","stoichiometry":0.2},{"gene":"RPN1","stoichiometry":0.2},{"gene":"RPN2","stoichiometry":0.2},{"gene":"SSRP1","stoichiometry":0.2},{"gene":"STT3B","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/TONSL","total_profiled":1310},"omim":[{"mim_id":"615614","title":"MMS22-LIKE PROTEIN; MMS22L","url":"https://www.omim.org/entry/615614"},{"mim_id":"615383","title":"FIDGETIN-LIKE PROTEIN 1; FIGNL1","url":"https://www.omim.org/entry/615383"},{"mim_id":"604546","title":"TONSOKU-LIKE DNA REPAIR PROTEIN; TONSL","url":"https://www.omim.org/entry/604546"},{"mim_id":"602822","title":"H4 CLUSTERED HISTONE 1; H4C1","url":"https://www.omim.org/entry/602822"},{"mim_id":"271510","title":"SPONDYLOEPIMETAPHYSEAL DYSPLASIA, SPONASTRIME TYPE; SEMDSP","url":"https://www.omim.org/entry/271510"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Nuclear bodies","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"bone marrow","ntpm":8.0}],"url":"https://www.proteinatlas.org/search/TONSL"},"hgnc":{"alias_symbol":["IKBR"],"prev_symbol":["NFKBIL2"]},"alphafold":{"accession":"Q96HA7","domains":[{"cath_id":"1.25.40.10","chopping":"4-216","consensus_level":"medium","plddt":94.2938,"start":4,"end":216},{"cath_id":"-","chopping":"385-458","consensus_level":"medium","plddt":92.3761,"start":385,"end":458},{"cath_id":"1.25.40.20","chopping":"533-668","consensus_level":"medium","plddt":92.8886,"start":533,"end":668},{"cath_id":"3.10.20","chopping":"949-1012","consensus_level":"medium","plddt":85.0872,"start":949,"end":1012}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96HA7","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q96HA7-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q96HA7-F1-predicted_aligned_error_v6.png","plddt_mean":75.25},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TONSL","jax_strain_url":"https://www.jax.org/strain/search?query=TONSL"},"sequence":{"accession":"Q96HA7","fasta_url":"https://rest.uniprot.org/uniprotkb/Q96HA7.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q96HA7/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96HA7"}},"corpus_meta":[{"pmid":"27338793","id":"PMC_27338793","title":"H4K20me0 marks post-replicative chromatin and recruits the TONSL–MMS22L DNA repair complex.","date":"2016","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/27338793","citation_count":178,"is_preprint":false},{"pmid":"21055983","id":"PMC_21055983","title":"The MMS22L-TONSL complex mediates recovery from replication stress and homologous recombination.","date":"2010","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/21055983","citation_count":122,"is_preprint":false},{"pmid":"21055985","id":"PMC_21055985","title":"A genome-wide camptothecin sensitivity screen identifies a mammalian MMS22L-NFKBIL2 complex required for genomic stability.","date":"2010","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/21055985","citation_count":107,"is_preprint":false},{"pmid":"21055984","id":"PMC_21055984","title":"Identification of the MMS22L-TONSL complex that promotes homologous recombination.","date":"2010","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/21055984","citation_count":104,"is_preprint":false},{"pmid":"29478807","id":"PMC_29478807","title":"The Histone Chaperones ASF1 and CAF-1 Promote MMS22L-TONSL-Mediated Rad51 Loading onto ssDNA during Homologous Recombination in Human Cells.","date":"2018","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/29478807","citation_count":81,"is_preprint":false},{"pmid":"27797818","id":"PMC_27797818","title":"The MMS22L-TONSL heterodimer directly promotes RAD51-dependent recombination upon replication stress.","date":"2016","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/27797818","citation_count":75,"is_preprint":false},{"pmid":"21113133","id":"PMC_21113133","title":"RNAi-based screening identifies the Mms22L-Nfkbil2 complex as a novel regulator of DNA replication in human cells.","date":"2010","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/21113133","citation_count":69,"is_preprint":false},{"pmid":"30773277","id":"PMC_30773277","title":"Bi-allelic Variants in TONSL Cause SPONASTRIME Dysplasia and a Spectrum of Skeletal Dysplasia Phenotypes.","date":"2019","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/30773277","citation_count":27,"is_preprint":false},{"pmid":"30773278","id":"PMC_30773278","title":"Hypomorphic Mutations in TONSL Cause SPONASTRIME Dysplasia.","date":"2019","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/30773278","citation_count":18,"is_preprint":false},{"pmid":"32414422","id":"PMC_32414422","title":"LncRNA TONSL-AS1 regulates miR-490-3p/CDK1 to affect ovarian epithelial carcinoma cell proliferation.","date":"2020","source":"Journal of ovarian research","url":"https://pubmed.ncbi.nlm.nih.gov/32414422","citation_count":15,"is_preprint":false},{"pmid":"36622344","id":"PMC_36622344","title":"MMS22L-TONSL functions in sister chromatid cohesion in a pathway parallel to DSCC1-RFC.","date":"2022","source":"Life science alliance","url":"https://pubmed.ncbi.nlm.nih.gov/36622344","citation_count":14,"is_preprint":false},{"pmid":"37057595","id":"PMC_37057595","title":"TONSL Is an Immortalizing Oncogene and a Therapeutic Target in Breast Cancer.","date":"2023","source":"Cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/37057595","citation_count":13,"is_preprint":false},{"pmid":"36012288","id":"PMC_36012288","title":"The Role of the TSK/TONSL-H3.1 Pathway in Maintaining Genome Stability in Multicellular Eukaryotes.","date":"2022","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/36012288","citation_count":12,"is_preprint":false},{"pmid":"37298484","id":"PMC_37298484","title":"Oncogenic Impact of TONSL, a Homologous Recombination Repair Protein at the Replication Fork, in Cancer Stem Cells.","date":"2023","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/37298484","citation_count":10,"is_preprint":false},{"pmid":"33662410","id":"PMC_33662410","title":"LncRNA TONSL-AS1 participates in coronary artery disease by interacting with miR-197.","date":"2021","source":"Microvascular research","url":"https://pubmed.ncbi.nlm.nih.gov/33662410","citation_count":9,"is_preprint":false},{"pmid":"31158361","id":"PMC_31158361","title":"A novel long non-coding RNA TONSL-AS1 regulates progression of gastric cancer via activating TONSL.","date":"2019","source":"Experimental cell research","url":"https://pubmed.ncbi.nlm.nih.gov/31158361","citation_count":5,"is_preprint":false},{"pmid":"11246458","id":"PMC_11246458","title":"Isolation, sequence, and chromosomal localisation of the human IkappaBR gene (NFKBIL2).","date":"2000","source":"Annals of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/11246458","citation_count":5,"is_preprint":false},{"pmid":"34630715","id":"PMC_34630715","title":"MicroRNA-135a expression is upregulated in hepatocellular carcinoma and targets long non-coding RNA TONSL-AS1 to suppress cell proliferation.","date":"2021","source":"Oncology letters","url":"https://pubmed.ncbi.nlm.nih.gov/34630715","citation_count":4,"is_preprint":false},{"pmid":"32959051","id":"PMC_32959051","title":"Novel TONSL variants cause SPONASTRIME dysplasia and associate with spontaneous chromosome breaks, defective cell proliferation and apoptosis.","date":"2020","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/32959051","citation_count":4,"is_preprint":false},{"pmid":"39097545","id":"PMC_39097545","title":"TONSL promotes lung adenocarcinoma progression, immune escape and drug sensitivity.","date":"2024","source":"Clinical & translational oncology : official publication of the Federation of Spanish Oncology Societies and of the National Cancer Institute of Mexico","url":"https://pubmed.ncbi.nlm.nih.gov/39097545","citation_count":2,"is_preprint":false},{"pmid":"41896213","id":"PMC_41896213","title":"TONSL suppresses polymerase theta-dependent tandem duplications through chromatin-guided repair.","date":"2026","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/41896213","citation_count":2,"is_preprint":false},{"pmid":"38684304","id":"PMC_38684304","title":"[Analysis of a child with SPONASTRIME dysplasia due to compound heterozygous variants of TONSL gene].","date":"2024","source":"Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/38684304","citation_count":1,"is_preprint":false},{"pmid":"41030968","id":"PMC_41030968","title":"The TONSL-MMS22L complex and FANCM form an interdependent complex on chromatin to counter replication stress.","date":"2025","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/41030968","citation_count":0,"is_preprint":false},{"pmid":"39713323","id":"PMC_39713323","title":"H3.1K27M-induced misregulation of the TSK/TONSL-H3.1 pathway causes genomic instability.","date":"2024","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/39713323","citation_count":0,"is_preprint":false},{"pmid":"41817780","id":"PMC_41817780","title":"TONSL promotes hepatocellular carcinoma progression and radioresistance by orchestrating DNA damage repair and cell cycle dynamics.","date":"2026","source":"Discover oncology","url":"https://pubmed.ncbi.nlm.nih.gov/41817780","citation_count":0,"is_preprint":false},{"pmid":"42037569","id":"PMC_42037569","title":"TONSL Promotes Hepatocellular Carcinoma Progression by Inhibiting Apoptosis Through Homologous Recombination Repair.","date":"2026","source":"Cancer science","url":"https://pubmed.ncbi.nlm.nih.gov/42037569","citation_count":0,"is_preprint":false},{"pmid":"40794898","id":"PMC_40794898","title":"A case report of SPONASTRIME dysplasia with novel TONSL mutation: genetic analysis, clinical manifestations, and the effect of growth hormone treatment.","date":"2025","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/40794898","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.11.03.621741","title":"FIGNL1 inhibits homologous recombination in BRCA2 deficient cells by dissociating RAD51 filaments","date":"2024-11-03","source":"bioRxiv","url":"https://doi.org/10.1101/2024.11.03.621741","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":15530,"output_tokens":3843,"usd":0.052117,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":11636,"output_tokens":4112,"usd":0.08049,"stage2_stop_reason":"end_turn"},"total_usd":0.132607,"stage1_batch_id":"msgbatch_017qqVz33Ga63SCDwzb35XPb","stage2_batch_id":"msgbatch_01Scr2Ei9x4HJMiRGxwrmvLK","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2010,\n      \"finding\": \"TONSL (NFKBIL2) forms a stable heterodimeric complex with MMS22L (C6ORF167). The complex accumulates at regions of ssDNA associated with distressed replication forks or processed DNA breaks, and is required for efficient RAD51 foci formation and homologous recombination-mediated repair of stalled or collapsed replication forks.\",\n      \"method\": \"Co-immunoprecipitation, RNAi depletion with RAD51 foci assay, camptothecin sensitivity assay, immunofluorescence localization\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — independently replicated across three simultaneous publications (PMIDs 21055983, 21055984, 21055985) using reciprocal Co-IP, localization, and functional RAD51 loading assays\",\n      \"pmids\": [\"21055983\", \"21055984\", \"21055985\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"MMS22L-TONSL (NFKBIL2) interacts with the FACT (facilitator of chromatin transcription) and MCM (minichromosome maintenance) complexes, and TONSL co-purifies with histones and multiple chromatin remodelling and DNA replication/repair factors.\",\n      \"method\": \"Mass spectrometry-based affinity purification, co-immunoprecipitation\",\n      \"journal\": \"Molecular cell / The EMBO journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — identified by AP-MS in two independent studies but full reciprocal validation not described in abstracts\",\n      \"pmids\": [\"21055985\", \"21113133\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Loss of MMS22L-TONSL results in S phase-dependent spontaneous DNA double-strand breaks, checkpoint activation, and inability to complete DNA synthesis after replication fork collapse, placing the complex at replication forks as a genome caretaker.\",\n      \"method\": \"RNAi knockdown, γH2AX foci assay, cell cycle analysis, live-cell imaging-based RNAi screen\",\n      \"journal\": \"Molecular cell / The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — replicated in multiple independent labs with consistent phenotypic readouts (DSBs, checkpoint activation, fork collapse)\",\n      \"pmids\": [\"21055983\", \"21055984\", \"21055985\", \"21113133\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The TONSL ankyrin repeat domain (ARD) functions as a reader of histone H4 tails unmethylated at K20 (H4K20me0), a mark specific to newly incorporated histones post-replication. This interaction recruits TONSL-MMS22L to post-replicative chromatin and is required for TONSL-MMS22L binding to chromatin and accumulation at challenged replication forks and DNA lesions. TONSL ARD mutants are toxic, compromising genome stability and cell viability.\",\n      \"method\": \"Histone peptide pulldown, domain mapping/mutagenesis of TONSL ARD, chromatin fractionation, cell cycle analysis (H4K20me0 dynamics), replication fork accumulation assay, viability assay with ARD mutants\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro peptide binding assay with mutagenesis, structural domain identification, multiple orthogonal functional validations in one rigorous study\",\n      \"pmids\": [\"27338793\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The MMS22L subunit of the MMS22L-TONSL heterodimer directly interacts with RAD51 and limits RAD51 assembly on dsDNA, thereby stimulating RAD51-ssDNA nucleoprotein filament formation and RAD51-dependent strand exchange activity in vitro. MMS22L-TONSL also associates with RPA-coated ssDNA at replication forks and promotes replication fork reversal and HR-mediated restart of stalled forks in vivo.\",\n      \"method\": \"In vitro RAD51 strand exchange assay with recombinant MMS22L-TONSL, Co-IP for RAD51 interaction, iPOND for replication fork localization, cell-based HR assay with MMS22L RAD51-interaction mutant\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with recombinant protein plus mutagenesis and in vivo functional validation in one study\",\n      \"pmids\": [\"27797818\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Recruitment of MMS22L-TONSL to ssDNA during homologous recombination depends on the histone chaperones ASF1 and CAF-1. Knockdown of ASF1 or CAF-1, or a mutation preventing ASF1A binding to histones, reduces MMS22L-TONSL recruitment and impairs RAD51 loading onto ssDNA, resulting in persistent RPA foci, extensive DNA end resection, persistent ATR-Chk1 activation, and cell cycle arrest. Additionally, DNA-PKcs-dependent phosphorylation of ASF1A upon DNA damage enhances chromatin assembly and promotes MMS22L-TONSL recruitment.\",\n      \"method\": \"RNAi knockdown of ASF1/CAF-1, ASF1A phosphorylation assay, RAD51 and RPA foci assay, cell cycle analysis, DNA end resection assay, co-immunoprecipitation\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (knockdown, phospho-mutant, foci assays, cell cycle) in a single rigorous study establishing pathway position\",\n      \"pmids\": [\"29478807\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"MMS22L-TONSL functions in sister chromatid cohesion (SCC) establishment in a pathway parallel to DSCC1-RFC. Synthetic lethality between DSCC1 and MMS22L loss results from detrimental SCC loss. MMS22L-TONSL and DSCC1-RFC both facilitate ESCO2 recruitment to replication forks, suggesting that distinct ESCO2 recruitment pathways promote SCC establishment.\",\n      \"method\": \"Genome-wide CRISPR synthetic lethality screen in DSCC1-KO cells, SCC assays, epistasis analysis, ESCO2 recruitment assay\",\n      \"journal\": \"Life science alliance\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR screen with epistasis and ESCO2 recruitment follow-up, single lab\",\n      \"pmids\": [\"36622344\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Hypomorphic bi-allelic loss-of-function variants in TONSL cause SPONASTRIME dysplasia; subject-derived cell lines exhibit increased spontaneous replication fork stalling, chromosomal aberrations, and reduced CPT-induced RAD51 foci, all rescued by re-expression of wild-type TONSL. Tonsl-/- mice show early embryonic lethality and tonsl-/- zebrafish show reduced length, spinal abnormalities, and early lethality.\",\n      \"method\": \"Whole-exome sequencing, rescue experiment (WT TONSL re-expression), DNA fiber assay, chromosomal aberration analysis, RAD51 foci assay, mouse/zebrafish knockout models\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — independently replicated in two simultaneous papers with rescue experiments, animal models, and multiple cellular assays\",\n      \"pmids\": [\"30773277\", \"30773278\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TONSL overexpression alone immortalizes primary breast epithelial cells, increases telomerase activity, and increases chromatin accessibility to pro-oncogenic transcription factors including NF-κB while limiting access to p53. TONSL-overexpressing cells are sensitive to the TONSL-FACT complex inhibitor CBL0137.\",\n      \"method\": \"hTERT-immortalization comparison transcriptomics, primary breast cell immortalization assay, ATAC-seq for chromatin accessibility, in vivo tumor formation, CBL0137 sensitivity assay\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (chromatin accessibility, immortalization assay, drug sensitivity) in single lab study\",\n      \"pmids\": [\"37057595\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"TONSL-MMS22L and FANCM form an interdependent complex on chromatin upon replication stress. TONSL-MMS22L recruits FANCM and the FA core complex to stalled and collapsed forks, maintains FANCM on stressed chromatin, promotes FANCD2 monoubiquitination, and facilitates both HR-mediated repair and replication traverse of DNA interstrand crosslinks. Reciprocally, FANCM DNA translocase activity and FANCM phosphorylation facilitate recruitment of TONSL-MMS22L and RAD51 to perturbed forks.\",\n      \"method\": \"Co-immunoprecipitation, chromatin fractionation, FANCD2 ubiquitination assay, ICL repair assay, replication traverse assay, phosphorylation mutant analysis\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple biochemical and functional assays in a single preprint lab study, not yet peer-reviewed\",\n      \"pmids\": [\"41030968\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"TONSL suppresses tandem duplication (TD) formation dependent on polymerase theta-mediated end joining (TMEJ). Loss of TONSL (tnsl-1) in C. elegans results in accumulation of TDs in two distinct size classes (~25 kb and ~300 kb) arising in different developmental contexts; both classes require polymerase theta. Inhibition of break-induced replication (BIR) via Pif1 helicase loss reduces TD size. The same TD signature is seen in TONSL-deficient Arabidopsis, demonstrating evolutionary conservation.\",\n      \"method\": \"C. elegans tnsl-1 knockout, whole-genome sequencing for TD detection, genetic epistasis with polymerase theta and Pif1 mutants, Arabidopsis TONSL knockout\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with multiple mutants across two organisms, whole-genome sequencing readout, mechanistic pathway placement\",\n      \"pmids\": [\"41896213\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"The MMS22L-TONSL complex interacts with FIGNL1 (an anti-recombinase that dissociates RAD51 filaments) and is critical for HR in BRCA2/FIGNL1 double-deficient cells, positioning TONSL-MMS22L in a pathway that regulates RAD51 activity downstream of BRCA2.\",\n      \"method\": \"Co-immunoprecipitation, BRCA2/FIGNL1 double-deficient cell viability and HR assay, RAD51 foci analysis\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single preprint, TONSL-MMS22L interaction with FIGNL1 is a secondary finding described only briefly in the abstract\",\n      \"pmids\": [\"bio_10.1101_2024.11.03.621741\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Loss of TONSL in HCC cells impairs RAD51 recruitment to DNA damage sites, resulting in defective homologous recombination repair and enhanced apoptosis. TONSL-knockout HCC cells show increased sensitivity to PARP inhibitors and reduced xenograft tumor growth.\",\n      \"method\": \"TONSL knockout (CRISPR), RAD51 foci assay, HR repair assay, PARP inhibitor sensitivity assay, xenograft model\",\n      \"journal\": \"Cancer science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct KO with multiple orthogonal functional readouts (RAD51 foci, HR assay, PARP inhibitor sensitivity, in vivo), single lab\",\n      \"pmids\": [\"42037569\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"The TONSL gene (NFKBIL2/IkappaBR) was cloned and characterized; revised mRNA and protein sequence predicted a larger protein than originally described. The gene was mapped to chromosome 8q24.3. The ankyrin-repeat region of TONSL has intron-exon junction positions different from other IkappaBs, indicating it is not a canonical IkappaB family member.\",\n      \"method\": \"cDNA cloning, genomic sequencing, PCR-based somatic cell hybrid panel, FISH mapping\",\n      \"journal\": \"Annals of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct molecular characterization by cloning and chromosomal mapping, single lab\",\n      \"pmids\": [\"11246458\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TONSL is a multi-domain scaffold protein that forms a stable heterodimer with MMS22L; its ankyrin repeat domain reads H4K20me0 on newly deposited histones to target the complex to post-replicative chromatin, where MMS22L directly interacts with RAD51 to stimulate ssDNA nucleofilament formation and strand exchange, suppress dsDNA-bound RAD51, promote replication fork reversal, establish sister chromatid cohesion via an ESCO2 recruitment pathway, recruit FANCM and the FA core complex for interstrand crosslink repair, suppress polymerase-theta-dependent tandem duplications, and depend on histone chaperones ASF1/CAF-1 for its own recruitment to ssDNA during homologous recombination.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TONSL is a multi-domain scaffold protein that operates as a genome caretaker at replication forks, where it forms a stable heterodimer with MMS22L that accumulates at ssDNA generated by distressed forks or processed breaks and is required for efficient RAD51 focus formation and homologous-recombination-mediated repair [#0, #2]. The complex is targeted to post-replicative chromatin through the TONSL ankyrin-repeat domain, which reads histone H4 unmethylated at K20 (H4K20me0), a mark restricted to newly deposited histones [#3]. Within the heterodimer the MMS22L subunit directly binds RAD51, suppresses unproductive RAD51 assembly on dsDNA, and stimulates RAD51-ssDNA nucleofilament formation and strand exchange, while the complex associates with RPA-coated ssDNA to promote fork reversal and HR-mediated restart [#4]. Recruitment of MMS22L-TONSL to ssDNA depends on the histone chaperones ASF1 and CAF-1, with DNA-PKcs-dependent ASF1A phosphorylation enhancing its loading after damage [#5]. Beyond canonical HR, TONSL-MMS22L contributes to sister chromatid cohesion via an ESCO2 recruitment pathway parallel to DSCC1-RFC [#6], recruits FANCM and the FA core complex to drive interstrand-crosslink repair and fork traverse [#9], and suppresses polymerase-theta-dependent tandem duplications, a function conserved across worms and plants [#10]. Hypomorphic bi-allelic loss-of-function variants in TONSL cause SPONASTRIME dysplasia, with patient cells showing fork stalling, chromosomal aberrations, and reduced RAD51 foci that are rescued by wild-type TONSL [#7]. TONSL overexpression immortalizes primary breast epithelial cells and remodels chromatin accessibility toward pro-oncogenic factors, and TONSL loss confers PARP-inhibitor sensitivity, linking the gene to tumorigenesis and synthetic-lethal vulnerability [#8, #12].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Before any DNA-repair role was known, the gene had to be defined at the molecular level; cloning established TONSL/NFKBIL2 as a distinct ankyrin-repeat protein rather than a canonical IkappaB family member.\",\n      \"evidence\": \"cDNA cloning, genomic sequencing, and FISH mapping to chromosome 8q24.3\",\n      \"pmids\": [\"11246458\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No functional role assigned at this stage\", \"Ankyrin-repeat function uncharacterized\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"The central question of what TONSL does was answered by identifying its stable partner MMS22L and placing the heterodimer at ssDNA on distressed forks, where it is required for RAD51 loading and HR repair.\",\n      \"evidence\": \"Co-IP, RNAi depletion with RAD51 foci and camptothecin sensitivity assays, immunofluorescence across three simultaneous studies plus a fourth\",\n      \"pmids\": [\"21055983\", \"21055984\", \"21055985\", \"21113133\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of RAD51 stimulation not yet resolved\", \"Mode of chromatin targeting unknown\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"To connect the complex to chromatin machinery, AP-MS identified FACT, MCM, and histone associations, hinting that the complex acts in a replication/chromatin context.\",\n      \"evidence\": \"Mass spectrometry-based affinity purification and Co-IP in two independent studies\",\n      \"pmids\": [\"21055985\", \"21113133\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct vs indirect interactions not distinguished\", \"Functional significance of FACT/MCM binding untested here\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"The unresolved targeting mechanism was solved by showing the TONSL ankyrin-repeat domain reads H4K20me0, explaining how the complex is restricted to newly replicated chromatin.\",\n      \"evidence\": \"Histone peptide pulldown, ARD mutagenesis, chromatin fractionation, fork-accumulation and viability assays\",\n      \"pmids\": [\"27338793\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of ARD-H4K20me0 recognition not fully detailed\", \"Coupling between reading and RAD51 loading unclear\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"The biochemical basis of RAD51 stimulation was established by showing MMS22L directly binds RAD51, suppresses dsDNA-bound RAD51, and promotes ssDNA filament formation and fork reversal.\",\n      \"evidence\": \"In vitro strand-exchange assay with recombinant MMS22L-TONSL, Co-IP, iPOND, and HR assay with interaction mutant\",\n      \"pmids\": [\"27797818\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"TONSL subunit's catalytic contribution to filament formation not defined\", \"Regulation of dsDNA suppression in vivo unclear\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"How the complex reaches ssDNA was clarified by placing histone chaperones ASF1/CAF-1 upstream of its recruitment and linking DNA-PKcs phosphorylation of ASF1A to enhanced loading.\",\n      \"evidence\": \"RNAi of ASF1/CAF-1, ASF1A phospho-mutant, RAD51/RPA foci, resection and cell-cycle assays\",\n      \"pmids\": [\"29478807\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct chaperone-TONSL contacts not mapped\", \"Order of chaperone and H4K20me0 engagement unresolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"The physiological and disease relevance was established by showing hypomorphic TONSL variants cause SPONASTRIME dysplasia with fork-stalling phenotypes rescued by wild-type protein, and that loss is lethal in mice and zebrafish.\",\n      \"evidence\": \"Whole-exome sequencing, WT rescue, DNA fiber and RAD51 foci assays, mouse and zebrafish knockouts in two simultaneous papers\",\n      \"pmids\": [\"30773277\", \"30773278\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How replication defects translate to skeletal dysplasia unclear\", \"Tissue-specific requirements undefined\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"A role beyond HR was uncovered by linking TONSL-MMS22L to sister chromatid cohesion via ESCO2 recruitment in a pathway parallel to DSCC1-RFC.\",\n      \"evidence\": \"Genome-wide CRISPR synthetic-lethality screen in DSCC1-KO cells, SCC and ESCO2 recruitment assays, epistasis\",\n      \"pmids\": [\"36622344\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of ESCO2 recruitment by the complex unknown\", \"Single-lab finding\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"An oncogenic dimension was identified by showing TONSL overexpression immortalizes breast epithelial cells and reshapes chromatin accessibility, with sensitivity to a TONSL-FACT inhibitor.\",\n      \"evidence\": \"Immortalization assay, ATAC-seq, in vivo tumor formation, CBL0137 sensitivity\",\n      \"pmids\": [\"37057595\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct chromatin targets of TONSL in transformation undefined\", \"Mechanistic link between FACT and accessibility changes unclear\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"The complex was integrated into the Fanconi anemia ICL-repair network by showing an interdependent TONSL-MMS22L/FANCM relationship that promotes FANCD2 monoubiquitination and fork traverse.\",\n      \"evidence\": \"Co-IP, chromatin fractionation, FANCD2 ubiquitination, ICL repair and traverse assays, phospho-mutant analysis (preprint)\",\n      \"pmids\": [\"41030968\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Not yet peer-reviewed\", \"Direct vs indirect FANCM contact not fully resolved\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"A conserved mutational-suppression role was demonstrated by showing TONSL loss causes polymerase-theta-dependent tandem duplications across worm and plant systems.\",\n      \"evidence\": \"C. elegans and Arabidopsis knockouts, whole-genome sequencing of TDs, epistasis with polymerase theta and Pif1\",\n      \"pmids\": [\"41896213\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct molecular step at which TONSL blocks TMEJ undefined\", \"Human relevance not directly tested\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Therapeutic vulnerability was shown by demonstrating that TONSL loss impairs RAD51 recruitment in HCC, sensitizing cells to PARP inhibitors and reducing tumor growth.\",\n      \"evidence\": \"CRISPR knockout, RAD51 foci and HR assays, PARP inhibitor sensitivity, xenograft model\",\n      \"pmids\": [\"42037569\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Generalizability across tumor types untested\", \"Single-lab finding\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the multiple TONSL-MMS22L functions—RAD51 loading, cohesion, ICL repair, and TD suppression—are coordinated and switched at a single fork remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of the full heterodimer on chromatin\", \"Unclear how distinct downstream pathways are partitioned\", \"FIGNL1 interaction remains a single low-confidence preprint observation\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0042393\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 4]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0000228\", \"supporting_discovery_ids\": [3, 5]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [0, 4, 9]},\n      {\"term_id\": \"R-HSA-69306\", \"supporting_discovery_ids\": [2, 4]},\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [3, 8]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"complexes\": [\n      \"MMS22L-TONSL heterodimer\"\n    ],\n    \"partners\": [\n      \"MMS22L\",\n      \"RAD51\",\n      \"ASF1\",\n      \"CAF-1\",\n      \"FANCM\",\n      \"ESCO2\",\n      \"FIGNL1\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}