{"gene":"LARP7","run_date":"2026-04-28T18:30:27","timeline":{"discoveries":[{"year":2008,"finding":"LARP7 is a stable, core component of the 7SK snRNP that binds 7SK snRNA and is required for maintaining steady-state 7SK levels; immunodepletion of LARP7 co-depletes 7SK regardless of P-TEFb, HEXIM1, or hnRNP A1 association, and siRNA knockdown of LARP7 decreases 7SK levels, increases free P-TEFb, and increases Tat transactivation of HIV-1 LTR.","method":"Glycerol gradient sedimentation, immunodepletion, siRNA knockdown with functional readouts (P-TEFb levels, Tat transactivation assay)","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 2 — reciprocal co-depletion, multiple orthogonal methods, replicated in same study","pmids":["18281698"],"is_preprint":false},{"year":2008,"finding":"LARP7 binds the highly conserved 3'-terminal U-rich stretch of 7SK RNA, is an integral part of the 7SK RNP, remains associated with 7SK upon P-TEFb release, and acts as a negative transcriptional regulator of RNA Pol II genes through the 7SK RNP system; siRNA-mediated reduction of LARP7 enhances transcription from cellular Pol II promoters and the TAT-dependent HIV-1 promoter.","method":"Co-immunoprecipitation, RNA interference, transcription reporter assays","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP and functional transcription assays; independently replicated finding from concurrent paper","pmids":["18483487"],"is_preprint":false},{"year":2013,"finding":"Larp7 binds to the 3'-terminal hairpin and following U-rich tail of 7SK snRNA, and MePCE interacts with the 5'-terminal helix-tail motif; binding of Larp7 to 7SK is a prerequisite for in vivo recruitment of P-TEFb to the 7SK snRNP, indicating Larp7 directly participates in P-TEFb regulation beyond merely stabilizing 7SK.","method":"In vivo RNA-protein interaction assays, mutational analysis of 7SK RNA elements","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 2 — in vivo RNA-protein interaction assays with systematic mutagenesis establishing epistatic requirement","pmids":["23471002"],"is_preprint":false},{"year":2015,"finding":"Crystal structure of the LARP7 La module (La motif + RRM1) bound to 3'-terminal uridines of 7SK shows the penultimate uridine is tethered by both domains; a second C-terminal RRM domain binds the apical loop of the 7SK 3' hairpin, and together the N- and C-terminal domains stabilize 7SK in a closed structure by joining conserved 5'-end sequences with the foot of the 3' hairpin.","method":"X-ray crystallography, binding assays, footprinting, small-angle X-ray scattering (SAXS)","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 — crystal structure with binding and SAXS validation, multiple orthogonal methods in single study","pmids":["25753663"],"is_preprint":false},{"year":2014,"finding":"Decreased LARP7 and 7SK levels redistribute P-TEFb to the transcriptionally active super elongation complex, resulting in increased transcription of EMT transcription factors (Slug, FOXC2, ZEB2, Twist1), promoting breast cancer EMT, invasion, and metastasis; LARP7 suppresses P-TEFb activity to inhibit these processes.","method":"siRNA knockdown, overexpression, invasion/migration assays, gene expression analysis","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 — loss-of-function with defined molecular pathway and multiple cellular phenotypic readouts","pmids":["25053741"],"is_preprint":false},{"year":2018,"finding":"Crystal structure (2.2 Å) of human Larp7 xRRM (C-terminal atypical RRM) bound to 7SK stem-loop 4 reveals a unique binding interface; the xRRM is preordered to bind a flexible loop 4; mutagenesis and ITC confirm specific contacts; combined with the La module structure, a model for full Larp7 binding to 7SK 3' end and mechanism for 7SK RNP assembly is proposed.","method":"X-ray crystallography (2.2 Å), NMR 13C spin relaxation, isothermal titration calorimetry, mutagenesis","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 — high-resolution crystal structure with NMR, ITC, and mutagenesis validation in single study","pmids":["29946027"],"is_preprint":false},{"year":2018,"finding":"Fission yeast LARP7 ortholog Lar7 binds telomerase RNA via conserved RNA-recognition motifs to protect it from exosomal degradation, stabilizes the association of telomerase RNA with the LSm2-8 complex and telomerase reverse transcriptase, and remains a component of the mature telomerase complex required for telomerase localization to the telomere.","method":"Genetic deletion, RNA-protein interaction assays, telomere localization assays (ortholog study in S. pombe)","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal experiments in orthologous system with direct functional consequences","pmids":["29422501"],"is_preprint":false},{"year":2018,"finding":"Fission yeast LARP7-like protein Pof8 uses its C-terminal xRRM domain to promote assembly of RNA Pol II-encoded telomerase RNA with TERT, and contributes to repression of noncoding RNA transcription at telomeres.","method":"Genetic analysis, domain deletion/mutation studies, RNA-protein interaction assays (ortholog study in S. pombe)","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 — domain-specific functional dissection with defined molecular and cellular phenotypes in ortholog","pmids":["29422503"],"is_preprint":false},{"year":2016,"finding":"LARP7 silencing in human cancer cells reduces telomerase enzymatic activity and causes progressive telomere shortening; Alazami syndrome patients with LARP7 loss-of-function show very short lymphocyte telomeres.","method":"siRNA knockdown, telomerase activity assay (TRAP), telomere length measurement, patient cohort analysis","journal":"BMC genomics","confidence":"Medium","confidence_rationale":"Tier 2 — enzymatic activity assay and direct measurement, but single lab study","pmids":["27766953"],"is_preprint":false},{"year":2020,"finding":"LARP7 physically connects the spliceosomal U6 snRNA with a distinct subset of box C/D snoRNAs guiding U6 2'-O-methylation; depletion of LARP7 severely compromises these U6 modifications and causes alternative splicing perturbations; Alazami syndrome patients carrying a LARP7 mutation show defective U6 2'-O-methylation.","method":"Co-immunoprecipitation, RNA modification analysis, transcriptome-wide splicing analysis, patient samples","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP establishing bridging function, modification assays, transcriptome analysis, and patient validation; replicated by concurrent independent study","pmids":["32017898"],"is_preprint":false},{"year":2020,"finding":"LARP7 promotes loading of U6 snRNA onto box C/D snoRNP, facilitating U6 2'-O-methylation; ablation of LARP7 in mouse male germline causes defective U6 2'-O-methylation, massive alterations in pre-mRNA splicing, and spermatogenic failure, rescued by wild-type LARP7 but not a U6-loading-deficient LARP7 mutant.","method":"Conditional knockout mouse, rescue with wild-type vs. mutant LARP7, U6 modification analysis, splicing transcriptome analysis","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 — in vivo loss-of-function with domain-specific rescue experiment distinguishing mechanism; replicated by concurrent independent study","pmids":["32017896"],"is_preprint":false},{"year":2021,"finding":"Cardiac-specific LARP7 knockout causes defective mitochondrial biogenesis, impaired oxidative phosphorylation, elevated oxidative stress, and heart failure; mechanistically, LARP7 loss reduces SIRT1 stability and deacetylase activity, impairing SIRT1-mediated transcription of oxidative phosphorylation and energy metabolism genes. Reactive oxygen species activate ATM kinase, which promotes LARP7 ubiquitination and degradation.","method":"Cardiac-specific and global KO mice, AAV9-mediated LARP7 overexpression, ATM inhibitor treatment, mitochondrial function assays, SIRT1 activity assays","journal":"Circulation","confidence":"High","confidence_rationale":"Tier 2 — multiple independent genetic models (global KO, conditional KO, somatic Cas9 KO), rescue experiments, and defined pathway with enzymatic readout","pmids":["33663221"],"is_preprint":false},{"year":2021,"finding":"DNA damage-mediated ATM activation triggers extracellular shuttling and downregulation of LARP7, which dampens SIRT1 deacetylase activity, enhances p53 and NF-κB (p65) transcriptional activity by augmenting their acetylation, accelerating cellular senescence; LARP7 deletion leads to senescent cell accumulation and premature aging in rodent model.","method":"LARP7 deletion in rodent model, SIRT1 deacetylase activity assays, acetylation analysis of p53/NF-κB, cellular senescence assays","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 — in vivo KO model with enzymatic activity measurements and defined substrate acetylation changes","pmids":["34818543"],"is_preprint":false},{"year":2019,"finding":"Legionella AnkH effector interacts with host nuclear LARP7 in the host cell nucleus, partially impeding interactions of 7SK snRNP components with LARP7 and interfering with Pol II transcriptional elongation; a substitution in the third ankyrin repeat of AnkH diminishes LARP7-AnkH interaction and phenocopies ankH null mutant defect in intracellular growth.","method":"Co-immunoprecipitation, crystal structure of AnkH, site-directed mutagenesis, bacterial infection assays","journal":"mBio","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP and structure with functional mutagenesis, but mechanistic detail on LARP7 side is indirect","pmids":["31455655"],"is_preprint":false},{"year":2015,"finding":"In zebrafish, Larp7 knockdown de-represses Cdk9 activity, increases phosphorylation of Ser2 on the C-terminal domain of RNA Pol II, and increases cardiomyocyte proliferation; Larp7 knockdown rescues the structural and functional cardiac phenotype caused by Cdk9 knockdown, placing Larp7 upstream of Cdk9/P-TEFb-mediated Pol II Ser2 phosphorylation in cardiomyocyte proliferation.","method":"Morpholino knockdown in zebrafish, epistasis analysis, Pol II CTD phosphorylation assay, cardiomyocyte proliferation and cardiac function readouts","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 — genetic epistasis in vivo with defined molecular readout (Pol II Ser2 phosphorylation), but in zebrafish ortholog context","pmids":["26542022"],"is_preprint":false},{"year":2022,"finding":"MCTS1 protein interacts with LARP7 (confirmed by reciprocal Co-IP, predominantly in cytoplasm), increases LARP7 protein half-life, and reduces LARP7 poly-ubiquitination, indicating MCTS1 stabilizes LARP7 by protecting it from proteasomal degradation.","method":"Co-immunoprecipitation, cycloheximide chase assay, ubiquitination Co-IP","journal":"Clinical and experimental pharmacology & physiology","confidence":"Medium","confidence_rationale":"Tier 2 — reciprocal Co-IP with biochemical demonstration of reduced ubiquitination and increased half-life, single lab","pmids":["35274760"],"is_preprint":false},{"year":2024,"finding":"LARP7 interacts with SIRT6 to maintain SIRT6 expression; combined cadmium and high-fat diet exposure reduces LARP7 levels via YTHDF2-mediated m6A-dependent degradation of Larp7 mRNA, disrupting LARP7-SIRT6 interaction and decreasing SIRT6 expression, leading to hippocampal neuronal senescence.","method":"RNA immunoprecipitation, RNA stability assays, Co-IP, Larp7 overexpression rescue, YTHDF2 siRNA","journal":"Journal of hazardous materials","confidence":"Medium","confidence_rationale":"Tier 2 — multiple orthogonal methods establishing m6A-YTHDF2 as writer/eraser of Larp7 mRNA and LARP7-SIRT6 protein interaction, single lab","pmids":["39002485"],"is_preprint":false},{"year":2024,"finding":"LARP7 and MePCE are involved in the early stage of human telomerase RNA (hTR) biogenesis; they bind 3'-extended precursor forms and their binding is destabilized upon mature hTR production; LARP7/MePCE depletion inhibits conversion of the 3'-extended short form to mature hTR and causes cytoplasmic accumulation of hTR, resulting in telomere shortening.","method":"Biochemical fractionation, RNA binding assays, depletion experiments, telomere length assays","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 — biochemical dissection of biogenesis steps with defined molecular intermediates and functional outcome, single lab","pmids":["39009594"],"is_preprint":false},{"year":2025,"finding":"HIV-1 infection triggers liquid-liquid phase separation of LARP7; Tat is incorporated into HIV-1-induced LARP7 condensates; conserved lysine residues in the intrinsically disordered region of LARP7 are essential for both its phase separation and inhibition of Tat-mediated transcription, sequestering P-TEFb and Tat within condensates to restrain HIV-1 transcription.","method":"Live cell imaging of LARP7 condensates, mutagenesis of IDR lysine residues, Tat-mediated transcription assays","journal":"EMBO reports","confidence":"Medium","confidence_rationale":"Tier 2 — live imaging with functional mutagenesis establishing IDR residues as essential for phase separation and Tat inhibition, single lab","pmids":["40113991"],"is_preprint":false},{"year":2025,"finding":"LARP7's C-terminal domain interacts with the N-terminal domain of SIRT1 to enhance SIRT1 deacetylase activity, which facilitates NLRP3 deacetylation at K21/K22/K24, inhibiting inflammasome assembly and neuronal pyroptosis after ischemic stroke; domain deletion analysis and co-immunoprecipitation define the interaction interface.","method":"Co-immunoprecipitation, domain deletion analysis, proximity ligation assay, acetyl-proteomics, SIRT1 deacetylase activity assay, neuron-specific LARP7 KO mice","journal":"Journal of neuroinflammation","confidence":"Medium","confidence_rationale":"Tier 2 — domain-mapped Co-IP with enzymatic activity assay and acetyl-proteomics identification of substrate sites, single lab","pmids":["41351020"],"is_preprint":false},{"year":2025,"finding":"In Drosophila, loss of Larp7 (ortholog) impairs locomotion and reduces axonal growth at neuromuscular junctions; Larp7 functions autonomously in motoneurons to promote axogenesis; reducing P-TEFb abundance partially rescues locomotion and axonal growth defects, placing Larp7 upstream of P-TEFb in transcriptional regulation of long, GC-rich promoter genes in motoneurons.","method":"Genetic deletion in Drosophila, locomotion assays, NMJ morphology analysis, genetic epistasis with P-TEFb reduction, transcriptomic analysis of mutant motoneurons","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 — genetic epistasis in vivo with transcriptomic characterization in orthologous Drosophila system, preprint not yet peer-reviewed","pmids":[],"is_preprint":true},{"year":2025,"finding":"LARP7 promotes replication fork slowing and RAD51-mediated replication fork reversal in response to agents that cause both replication and transcription stress (e.g., camptothecin, BET inhibitors), and supports homologous recombination at direct DSBs; this function is not required for HR in response to hydroxyurea (replication stress without transcription stress), indicating the mechanism is linked to LARP7's canonical 7SK-snRNP/Pol II regulatory function.","method":"LARP7 knockdown, DNA fiber assay (fork slowing), RAD51 recruitment assays, HR assays, epistasis with Pol II inhibition","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 3 — defined phenotypes with partial mechanistic follow-up, preprint not peer-reviewed","pmids":[],"is_preprint":true},{"year":2024,"finding":"LARP7 interacts with STING in cardiomyocytes (particularly under high glucose conditions); high glucose causes LARP7 to translocate from the nucleus to the cytoplasm where it interacts with accumulated STING to inhibit STING degradation via the autophagy-lysosomal pathway, contributing to cardiac dysfunction.","method":"Co-immunoprecipitation, immunofluorescence (subcellular localization), adenovirus-mediated knockdown/overexpression, STING inhibitor treatment","journal":"Frontiers in bioscience","confidence":"Low","confidence_rationale":"Tier 3 — single Co-IP with localization data but mechanistic pathway is partially characterized, single lab","pmids":["39082350"],"is_preprint":false},{"year":2024,"finding":"LARP7 is required for meiotic sex chromosome inactivation (MSCI) in mice; in germline-specific Larp7-deficient spermatocytes, LARP7 normally localizes to the XY body; its absence leads to failure of sex chromosome transcriptional silencing, accumulation of H4K12ac and loss of H3K9me2 on XY chromatin, and arrest of spermatogenesis.","method":"Germline-specific Larp7 KO mice, immunofluorescence (XY body localization), histone modification analysis, transcriptional analysis of sex chromosome genes","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 — conditional KO with direct localization and chromatin modification readouts establishing a new functional role, single lab","pmids":["39637191"],"is_preprint":false},{"year":2023,"finding":"Full-length Tetrahymena LARP7 protein p65 structure in telomerase was determined by cryo-EM combined with NMR; three previously unknown helices are identified (one in NTD that binds the La module, one extending RRM1, one preceding xRRM2) that stabilize p65-TER interactions; the extended La module interacts with four 3' terminal U nucleotides and additionally with the TER pseudoknot, stem 1, and 5' end.","method":"Cryo-EM focused classification, NMR spectroscopy (Tetrahymena ortholog p65)","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 — cryo-EM structure combined with NMR, revealing new structural elements in LARP7 family member","pmids":["37330293"],"is_preprint":false}],"current_model":"LARP7 is a stable core component of the 7SK snRNP that binds the 3'-terminal U-rich tail and 3' hairpin of 7SK snRNA (via its La module and C-terminal xRRM domain) to protect 7SK from degradation and maintain its structure; this positions LARP7 as a constitutive scaffold that sequesters P-TEFb in a transcriptionally inactive complex by facilitating HEXIM1 binding, thereby acting as a negative regulator of RNA Pol II transcriptional elongation; beyond 7SK, LARP7 serves as a bridging factor that guides 2'-O-methylation of spliceosomal U6 snRNA by connecting U6 to box C/D snoRNPs, promotes early human telomerase RNA biogenesis and processing, and allosterically enhances SIRT1 deacetylase activity through direct protein-protein interaction (C-terminal domain of LARP7 with N-terminal domain of SIRT1), thereby regulating downstream substrates including p53, NF-κB, and NLRP3 to modulate senescence, inflammation, and cardiac function."},"narrative":{"teleology":[{"year":2008,"claim":"Establishing LARP7 as a constitutive 7SK snRNP component resolved how 7SK RNA stability is maintained and linked LARP7 directly to P-TEFb regulation and Pol II transcriptional control.","evidence":"Glycerol gradient sedimentation, immunodepletion, siRNA knockdown with Tat transactivation and transcription reporter assays in human cells (two independent labs)","pmids":["18281698","18483487"],"confidence":"High","gaps":["Mechanism by which LARP7 facilitates HEXIM1 and P-TEFb recruitment was unresolved","Whether LARP7 has functions beyond 7SK was unknown"]},{"year":2013,"claim":"Mapping LARP7's binding to the 7SK 3' hairpin and U-tail and showing this binding is a prerequisite for P-TEFb recruitment demonstrated that LARP7 is not merely a passive stabilizer but actively participates in RNP assembly.","evidence":"In vivo RNA-protein interaction assays with systematic 7SK RNA mutagenesis","pmids":["23471002"],"confidence":"High","gaps":["Atomic-resolution structural basis for LARP7-7SK interaction was not yet available","How LARP7 binding triggers conformational changes enabling P-TEFb capture was unknown"]},{"year":2015,"claim":"Crystal structures of the LARP7 La module bound to 7SK 3' uridines and the demonstration that N- and C-terminal domains jointly stabilize a closed 7SK structure provided the first atomic-level model of how LARP7 organizes the 7SK snRNP.","evidence":"X-ray crystallography, SAXS, binding and footprinting assays","pmids":["25753663"],"confidence":"High","gaps":["Structure of the C-terminal xRRM bound to stem-loop 4 was not yet determined","How the full-length protein engages the complete 7SK was modeled but not resolved"]},{"year":2014,"claim":"Demonstrating that LARP7 depletion redistributes P-TEFb to super elongation complexes and upregulates EMT transcription factors established a concrete biological consequence—breast cancer invasion and metastasis—of 7SK/P-TEFb deregulation.","evidence":"siRNA knockdown and overexpression with invasion/migration assays and gene expression analysis in breast cancer cells","pmids":["25053741"],"confidence":"High","gaps":["Whether LARP7 loss is causal in human tumors versus a correlate was not established","Contribution of non-7SK functions of LARP7 to the cancer phenotype was not assessed"]},{"year":2015,"claim":"Zebrafish epistasis experiments placed Larp7 upstream of Cdk9/P-TEFb-mediated Pol II Ser2 phosphorylation in cardiomyocyte proliferation, extending the transcriptional control axis to cardiac development.","evidence":"Morpholino knockdown in zebrafish with epistasis analysis and Pol II CTD phosphorylation readouts","pmids":["26542022"],"confidence":"Medium","gaps":["Morpholino-based evidence in zebrafish; genetic mutant confirmation was not provided","Mammalian cardiac relevance was not yet demonstrated"]},{"year":2016,"claim":"Linking LARP7 to telomerase activity and demonstrating very short telomeres in Alazami syndrome patients expanded LARP7's functional repertoire beyond transcriptional regulation to telomere maintenance.","evidence":"siRNA knockdown with TRAP telomerase assay and telomere length measurement in human cells and patient lymphocytes","pmids":["27766953"],"confidence":"Medium","gaps":["Direct mechanism by which LARP7 supports human telomerase RNA (hTR) was unclear","Whether the telomere defect is independent of 7SK-mediated transcription changes was not resolved"]},{"year":2018,"claim":"A high-resolution crystal structure of the human LARP7 xRRM bound to 7SK stem-loop 4, combined with NMR dynamics, completed the structural picture of how LARP7's two RNA-binding domains jointly recognize and stabilize 7SK snRNA.","evidence":"2.2 Å X-ray crystallography, NMR ¹³C spin relaxation, ITC, and mutagenesis","pmids":["29946027"],"confidence":"High","gaps":["Full-length LARP7-7SK RNP structure remained unresolved","How structural changes propagate to HEXIM1/P-TEFb recruitment was mechanistically undetermined"]},{"year":2018,"claim":"Studies of fission yeast LARP7 orthologs (Lar7/Pof8) demonstrated that the conserved xRRM domain promotes telomerase RNA stability and TERT assembly, establishing an evolutionarily conserved function in telomerase biogenesis.","evidence":"Genetic deletion and domain mutagenesis with RNA-protein interaction and telomere localization assays in S. pombe","pmids":["29422501","29422503"],"confidence":"High","gaps":["Whether human LARP7 uses the same xRRM-dependent mechanism for hTR was not directly shown","How LARP7 transitions between 7SK and telomerase RNA targets was unknown"]},{"year":2019,"claim":"Identification of the Legionella effector AnkH as a nuclear interactor of LARP7 that partially disrupts 7SK snRNP assembly revealed that pathogens exploit LARP7-mediated transcriptional control for intracellular replication.","evidence":"Co-immunoprecipitation, crystal structure of AnkH, site-directed mutagenesis, and bacterial intracellular growth assays","pmids":["31455655"],"confidence":"Medium","gaps":["Precise mechanism by which AnkH disrupts LARP7-7SK contacts was not fully defined","Whether additional host targets of AnkH contribute to the phenotype was not excluded"]},{"year":2020,"claim":"Two concurrent studies demonstrated that LARP7 bridges U6 snRNA to box C/D snoRNPs for 2'-O-methylation, establishing a second major RNA chaperone function; LARP7 loss causes widespread splicing defects, and Alazami syndrome patients show defective U6 modification.","evidence":"Co-immunoprecipitation, RNA modification analysis, transcriptome-wide splicing analysis in human cells and patient samples; conditional KO mouse with domain-specific rescue","pmids":["32017898","32017896"],"confidence":"High","gaps":["How LARP7 simultaneously manages 7SK and U6 RNA clients was not resolved","Whether all Alazami syndrome pathology traces to U6 modification versus telomerase or P-TEFb defects was unclear"]},{"year":2021,"claim":"Discovery that LARP7 allosterically activates SIRT1 deacetylase activity uncovered a direct protein-protein mechanism outside RNA biology, linking LARP7 loss to p53/NF-κB hyperacetylation, senescence, and heart failure; ATM-mediated ubiquitination of LARP7 creates a damage-responsive feedback loop.","evidence":"Cardiac-specific and global KO mice, SIRT1 enzymatic activity assays, acetylation analysis of p53/NF-κB, senescence assays, ATM inhibitor rescue","pmids":["33663221","34818543"],"confidence":"High","gaps":["Whether SIRT1 activation by LARP7 is fully independent of 7SK/P-TEFb was not formally demonstrated","Structural basis of the LARP7-SIRT1 interaction was not determined"]},{"year":2023,"claim":"Cryo-EM/NMR structure of full-length Tetrahymena LARP7 (p65) in the telomerase complex revealed three previously unknown helices and expanded contacts with telomerase RNA beyond the 3' tail, providing the most complete structural view of how LARP7 family proteins organize a catalytic RNP.","evidence":"Cryo-EM focused classification and NMR spectroscopy of Tetrahymena p65 within telomerase","pmids":["37330293"],"confidence":"High","gaps":["Human LARP7 full-length structure in any RNP context remains undetermined","Whether the additional helices are conserved in vertebrate LARP7 is untested"]},{"year":2024,"claim":"Biochemical dissection of human telomerase RNA biogenesis showed LARP7 and MePCE bind 3'-extended hTR precursors and promote their maturation and nuclear retention, directly explaining LARP7's role in telomerase activity and telomere maintenance.","evidence":"Biochemical fractionation, RNA binding assays, depletion experiments, and telomere length assays in human cells","pmids":["39009594"],"confidence":"Medium","gaps":["Whether LARP7 escorts hTR through specific nuclear compartments was not resolved","Contribution of MePCE versus LARP7 to individual biogenesis steps was not fully disentangled"]},{"year":2024,"claim":"LARP7 was shown to be required for meiotic sex chromosome inactivation (MSCI), localizing to the XY body and maintaining repressive chromatin marks, revealing a chromatin-regulatory role during spermatogenesis.","evidence":"Germline-specific Larp7 KO mice, immunofluorescence, histone modification and transcriptional analysis","pmids":["39637191"],"confidence":"Medium","gaps":["Whether MSCI function depends on 7SK/P-TEFb sequestration or a distinct mechanism was not determined","No direct biochemical link between LARP7 and the MSCI silencing machinery was established"]},{"year":2025,"claim":"Discovery that LARP7 undergoes liquid-liquid phase separation upon HIV-1 infection, sequestering P-TEFb and Tat in condensates through IDR lysine residues, revealed a biophysical mechanism for LARP7's antiviral function.","evidence":"Live cell imaging, IDR lysine mutagenesis, Tat-mediated transcription assays","pmids":["40113991"],"confidence":"Medium","gaps":["Whether LARP7 phase separation occurs in non-HIV contexts was not explored","In vivo relevance for HIV-1 latency control was not demonstrated"]},{"year":2025,"claim":"Domain mapping of the LARP7-SIRT1 interaction (LARP7 C-terminal domain to SIRT1 N-terminal domain) and identification of NLRP3 K21/K22/K24 as SIRT1 deacetylation targets established a molecular pathway from LARP7 to inflammasome suppression and neuroprotection after ischemic stroke.","evidence":"Co-immunoprecipitation with domain deletions, proximity ligation assay, acetyl-proteomics, neuron-specific LARP7 KO mice","pmids":["41351020"],"confidence":"Medium","gaps":["Structural basis for allosteric SIRT1 activation by LARP7 C-terminal domain is unknown","Whether LARP7 regulates other SIRT1 substrates genome-wide was not assessed"]},{"year":null,"claim":"Key unresolved questions include: the structure of human full-length LARP7 in any RNP context; how LARP7 partitions among its distinct RNA clients (7SK, U6, hTR); whether SIRT1 activation is mechanistically separable from 7SK/P-TEFb regulation; and the relative contributions of each LARP7 function to Alazami syndrome pathology.","evidence":"","pmids":[],"confidence":"Low","gaps":["No human full-length LARP7 structure in any RNP complex","Client RNA partitioning mechanism unknown","Relative disease contribution of individual LARP7 functions not deconvolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[0,1,2,3,5,6,7,9,10,17,24]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[11,12,19]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[9,10]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,1,13,23]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[15,22]}],"pathway":[{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,1,2,4,14]},{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[9,10,17]},{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[11,12]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[8,17]}],"complexes":["7SK snRNP","telomerase RNP"],"partners":["MEPCE","HEXIM1","CDK9","SIRT1","MCTS1","STING","SIRT6"],"other_free_text":[]},"mechanistic_narrative":"LARP7 is a multifunctional RNA-binding protein that serves as a constitutive scaffold of the 7SK small nuclear ribonucleoprotein (snRNP), a negative regulator of RNA Polymerase II transcriptional elongation, and a bridging factor for RNA modification and telomerase biogenesis. Through its N-terminal La module and C-terminal xRRM domain, LARP7 binds the 3'-terminal U-rich tail and stem-loop 4 of 7SK snRNA, stabilizing 7SK levels and enabling sequestration of P-TEFb in an inactive complex; loss of LARP7 releases P-TEFb, enhancing Pol II Ser2 phosphorylation and transcription of target genes including EMT transcription factors and HIV-1 [PMID:18281698, PMID:18483487, PMID:25053741, PMID:29946027]. Independent of 7SK, LARP7 physically connects U6 snRNA to box C/D snoRNPs to guide 2'-O-methylation essential for proper pre-mRNA splicing, promotes early processing and nuclear retention of human telomerase RNA (hTR), and allosterically enhances SIRT1 deacetylase activity through direct C-terminal domain interaction, thereby modulating p53/NF-κB acetylation, inflammasome assembly, senescence, and cardiac function [PMID:32017898, PMID:32017896, PMID:39009594, PMID:34818543, PMID:33663221, PMID:41351020]. Loss-of-function mutations in LARP7 cause Alazami syndrome, associated with short telomeres and defective U6 2'-O-methylation [PMID:27766953, PMID:32017898]."},"prefetch_data":{"uniprot":{"accession":"Q4G0J3","full_name":"La-related protein 7","aliases":["La ribonucleoprotein domain family member 7","hLARP7","P-TEFb-interaction protein for 7SK stability","PIP7S"],"length_aa":582,"mass_kda":66.9,"function":"RNA-binding protein that specifically binds distinct small nuclear RNA (snRNAs) and regulates their processing and function (PubMed:18249148, PubMed:32017898). Specifically binds the 7SK snRNA (7SK RNA) and acts as a core component of the 7SK ribonucleoprotein (RNP) complex, thereby acting as a negative regulator of transcription elongation by RNA polymerase II (PubMed:18249148, PubMed:18483487). The 7SK RNP complex sequesters the positive transcription elongation factor b (P-TEFb) in a large inactive 7SK RNP complex preventing RNA polymerase II phosphorylation and subsequent transcriptional elongation (PubMed:18249148, PubMed:18483487). The 7SK RNP complex also promotes snRNA gene transcription by RNA polymerase II via interaction with the little elongation complex (LEC) (PubMed:28254838). LARP7 specifically binds to the highly conserved 3'-terminal U-rich stretch of 7SK RNA; on stimulation, remains associated with 7SK RNA, whereas P-TEFb is released from the complex (PubMed:18281698, PubMed:18483487). LARP7 also acts as a regulator of mRNA splicing fidelity by promoting U6 snRNA processing (PubMed:32017898). Specifically binds U6 snRNAs and associates with a subset of box C/D RNP complexes: promotes U6 snRNA 2'-O-methylation by facilitating U6 snRNA loading into box C/D RNP complexes (PubMed:32017898). U6 snRNA 2'-O-methylation is required for mRNA splicing fidelity (PubMed:32017898). Binds U6 snRNAs with a 5'-CAGGG-3' sequence motif (PubMed:32017898). 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the 7SK snRNP that binds 7SK snRNA and is required for maintaining steady-state 7SK levels; immunodepletion of LARP7 co-depletes 7SK regardless of P-TEFb, HEXIM1, or hnRNP A1 association, and siRNA knockdown of LARP7 decreases 7SK levels, increases free P-TEFb, and increases Tat transactivation of HIV-1 LTR.\",\n      \"method\": \"Glycerol gradient sedimentation, immunodepletion, siRNA knockdown with functional readouts (P-TEFb levels, Tat transactivation assay)\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal co-depletion, multiple orthogonal methods, replicated in same study\",\n      \"pmids\": [\"18281698\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"LARP7 binds the highly conserved 3'-terminal U-rich stretch of 7SK RNA, is an integral part of the 7SK RNP, remains associated with 7SK upon P-TEFb release, and acts as a negative transcriptional regulator of RNA Pol II genes through the 7SK RNP system; siRNA-mediated reduction of LARP7 enhances transcription from cellular Pol II promoters and the TAT-dependent HIV-1 promoter.\",\n      \"method\": \"Co-immunoprecipitation, RNA interference, transcription reporter assays\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP and functional transcription assays; independently replicated finding from concurrent paper\",\n      \"pmids\": [\"18483487\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Larp7 binds to the 3'-terminal hairpin and following U-rich tail of 7SK snRNA, and MePCE interacts with the 5'-terminal helix-tail motif; binding of Larp7 to 7SK is a prerequisite for in vivo recruitment of P-TEFb to the 7SK snRNP, indicating Larp7 directly participates in P-TEFb regulation beyond merely stabilizing 7SK.\",\n      \"method\": \"In vivo RNA-protein interaction assays, mutational analysis of 7SK RNA elements\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vivo RNA-protein interaction assays with systematic mutagenesis establishing epistatic requirement\",\n      \"pmids\": [\"23471002\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Crystal structure of the LARP7 La module (La motif + RRM1) bound to 3'-terminal uridines of 7SK shows the penultimate uridine is tethered by both domains; a second C-terminal RRM domain binds the apical loop of the 7SK 3' hairpin, and together the N- and C-terminal domains stabilize 7SK in a closed structure by joining conserved 5'-end sequences with the foot of the 3' hairpin.\",\n      \"method\": \"X-ray crystallography, binding assays, footprinting, small-angle X-ray scattering (SAXS)\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure with binding and SAXS validation, multiple orthogonal methods in single study\",\n      \"pmids\": [\"25753663\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Decreased LARP7 and 7SK levels redistribute P-TEFb to the transcriptionally active super elongation complex, resulting in increased transcription of EMT transcription factors (Slug, FOXC2, ZEB2, Twist1), promoting breast cancer EMT, invasion, and metastasis; LARP7 suppresses P-TEFb activity to inhibit these processes.\",\n      \"method\": \"siRNA knockdown, overexpression, invasion/migration assays, gene expression analysis\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — loss-of-function with defined molecular pathway and multiple cellular phenotypic readouts\",\n      \"pmids\": [\"25053741\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Crystal structure (2.2 Å) of human Larp7 xRRM (C-terminal atypical RRM) bound to 7SK stem-loop 4 reveals a unique binding interface; the xRRM is preordered to bind a flexible loop 4; mutagenesis and ITC confirm specific contacts; combined with the La module structure, a model for full Larp7 binding to 7SK 3' end and mechanism for 7SK RNP assembly is proposed.\",\n      \"method\": \"X-ray crystallography (2.2 Å), NMR 13C spin relaxation, isothermal titration calorimetry, mutagenesis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — high-resolution crystal structure with NMR, ITC, and mutagenesis validation in single study\",\n      \"pmids\": [\"29946027\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Fission yeast LARP7 ortholog Lar7 binds telomerase RNA via conserved RNA-recognition motifs to protect it from exosomal degradation, stabilizes the association of telomerase RNA with the LSm2-8 complex and telomerase reverse transcriptase, and remains a component of the mature telomerase complex required for telomerase localization to the telomere.\",\n      \"method\": \"Genetic deletion, RNA-protein interaction assays, telomere localization assays (ortholog study in S. pombe)\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal experiments in orthologous system with direct functional consequences\",\n      \"pmids\": [\"29422501\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Fission yeast LARP7-like protein Pof8 uses its C-terminal xRRM domain to promote assembly of RNA Pol II-encoded telomerase RNA with TERT, and contributes to repression of noncoding RNA transcription at telomeres.\",\n      \"method\": \"Genetic analysis, domain deletion/mutation studies, RNA-protein interaction assays (ortholog study in S. pombe)\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — domain-specific functional dissection with defined molecular and cellular phenotypes in ortholog\",\n      \"pmids\": [\"29422503\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"LARP7 silencing in human cancer cells reduces telomerase enzymatic activity and causes progressive telomere shortening; Alazami syndrome patients with LARP7 loss-of-function show very short lymphocyte telomeres.\",\n      \"method\": \"siRNA knockdown, telomerase activity assay (TRAP), telomere length measurement, patient cohort analysis\",\n      \"journal\": \"BMC genomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — enzymatic activity assay and direct measurement, but single lab study\",\n      \"pmids\": [\"27766953\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"LARP7 physically connects the spliceosomal U6 snRNA with a distinct subset of box C/D snoRNAs guiding U6 2'-O-methylation; depletion of LARP7 severely compromises these U6 modifications and causes alternative splicing perturbations; Alazami syndrome patients carrying a LARP7 mutation show defective U6 2'-O-methylation.\",\n      \"method\": \"Co-immunoprecipitation, RNA modification analysis, transcriptome-wide splicing analysis, patient samples\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP establishing bridging function, modification assays, transcriptome analysis, and patient validation; replicated by concurrent independent study\",\n      \"pmids\": [\"32017898\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"LARP7 promotes loading of U6 snRNA onto box C/D snoRNP, facilitating U6 2'-O-methylation; ablation of LARP7 in mouse male germline causes defective U6 2'-O-methylation, massive alterations in pre-mRNA splicing, and spermatogenic failure, rescued by wild-type LARP7 but not a U6-loading-deficient LARP7 mutant.\",\n      \"method\": \"Conditional knockout mouse, rescue with wild-type vs. mutant LARP7, U6 modification analysis, splicing transcriptome analysis\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vivo loss-of-function with domain-specific rescue experiment distinguishing mechanism; replicated by concurrent independent study\",\n      \"pmids\": [\"32017896\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Cardiac-specific LARP7 knockout causes defective mitochondrial biogenesis, impaired oxidative phosphorylation, elevated oxidative stress, and heart failure; mechanistically, LARP7 loss reduces SIRT1 stability and deacetylase activity, impairing SIRT1-mediated transcription of oxidative phosphorylation and energy metabolism genes. Reactive oxygen species activate ATM kinase, which promotes LARP7 ubiquitination and degradation.\",\n      \"method\": \"Cardiac-specific and global KO mice, AAV9-mediated LARP7 overexpression, ATM inhibitor treatment, mitochondrial function assays, SIRT1 activity assays\",\n      \"journal\": \"Circulation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple independent genetic models (global KO, conditional KO, somatic Cas9 KO), rescue experiments, and defined pathway with enzymatic readout\",\n      \"pmids\": [\"33663221\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"DNA damage-mediated ATM activation triggers extracellular shuttling and downregulation of LARP7, which dampens SIRT1 deacetylase activity, enhances p53 and NF-κB (p65) transcriptional activity by augmenting their acetylation, accelerating cellular senescence; LARP7 deletion leads to senescent cell accumulation and premature aging in rodent model.\",\n      \"method\": \"LARP7 deletion in rodent model, SIRT1 deacetylase activity assays, acetylation analysis of p53/NF-κB, cellular senescence assays\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vivo KO model with enzymatic activity measurements and defined substrate acetylation changes\",\n      \"pmids\": [\"34818543\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Legionella AnkH effector interacts with host nuclear LARP7 in the host cell nucleus, partially impeding interactions of 7SK snRNP components with LARP7 and interfering with Pol II transcriptional elongation; a substitution in the third ankyrin repeat of AnkH diminishes LARP7-AnkH interaction and phenocopies ankH null mutant defect in intracellular growth.\",\n      \"method\": \"Co-immunoprecipitation, crystal structure of AnkH, site-directed mutagenesis, bacterial infection assays\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP and structure with functional mutagenesis, but mechanistic detail on LARP7 side is indirect\",\n      \"pmids\": [\"31455655\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"In zebrafish, Larp7 knockdown de-represses Cdk9 activity, increases phosphorylation of Ser2 on the C-terminal domain of RNA Pol II, and increases cardiomyocyte proliferation; Larp7 knockdown rescues the structural and functional cardiac phenotype caused by Cdk9 knockdown, placing Larp7 upstream of Cdk9/P-TEFb-mediated Pol II Ser2 phosphorylation in cardiomyocyte proliferation.\",\n      \"method\": \"Morpholino knockdown in zebrafish, epistasis analysis, Pol II CTD phosphorylation assay, cardiomyocyte proliferation and cardiac function readouts\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis in vivo with defined molecular readout (Pol II Ser2 phosphorylation), but in zebrafish ortholog context\",\n      \"pmids\": [\"26542022\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"MCTS1 protein interacts with LARP7 (confirmed by reciprocal Co-IP, predominantly in cytoplasm), increases LARP7 protein half-life, and reduces LARP7 poly-ubiquitination, indicating MCTS1 stabilizes LARP7 by protecting it from proteasomal degradation.\",\n      \"method\": \"Co-immunoprecipitation, cycloheximide chase assay, ubiquitination Co-IP\",\n      \"journal\": \"Clinical and experimental pharmacology & physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP with biochemical demonstration of reduced ubiquitination and increased half-life, single lab\",\n      \"pmids\": [\"35274760\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"LARP7 interacts with SIRT6 to maintain SIRT6 expression; combined cadmium and high-fat diet exposure reduces LARP7 levels via YTHDF2-mediated m6A-dependent degradation of Larp7 mRNA, disrupting LARP7-SIRT6 interaction and decreasing SIRT6 expression, leading to hippocampal neuronal senescence.\",\n      \"method\": \"RNA immunoprecipitation, RNA stability assays, Co-IP, Larp7 overexpression rescue, YTHDF2 siRNA\",\n      \"journal\": \"Journal of hazardous materials\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods establishing m6A-YTHDF2 as writer/eraser of Larp7 mRNA and LARP7-SIRT6 protein interaction, single lab\",\n      \"pmids\": [\"39002485\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"LARP7 and MePCE are involved in the early stage of human telomerase RNA (hTR) biogenesis; they bind 3'-extended precursor forms and their binding is destabilized upon mature hTR production; LARP7/MePCE depletion inhibits conversion of the 3'-extended short form to mature hTR and causes cytoplasmic accumulation of hTR, resulting in telomere shortening.\",\n      \"method\": \"Biochemical fractionation, RNA binding assays, depletion experiments, telomere length assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — biochemical dissection of biogenesis steps with defined molecular intermediates and functional outcome, single lab\",\n      \"pmids\": [\"39009594\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"HIV-1 infection triggers liquid-liquid phase separation of LARP7; Tat is incorporated into HIV-1-induced LARP7 condensates; conserved lysine residues in the intrinsically disordered region of LARP7 are essential for both its phase separation and inhibition of Tat-mediated transcription, sequestering P-TEFb and Tat within condensates to restrain HIV-1 transcription.\",\n      \"method\": \"Live cell imaging of LARP7 condensates, mutagenesis of IDR lysine residues, Tat-mediated transcription assays\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — live imaging with functional mutagenesis establishing IDR residues as essential for phase separation and Tat inhibition, single lab\",\n      \"pmids\": [\"40113991\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"LARP7's C-terminal domain interacts with the N-terminal domain of SIRT1 to enhance SIRT1 deacetylase activity, which facilitates NLRP3 deacetylation at K21/K22/K24, inhibiting inflammasome assembly and neuronal pyroptosis after ischemic stroke; domain deletion analysis and co-immunoprecipitation define the interaction interface.\",\n      \"method\": \"Co-immunoprecipitation, domain deletion analysis, proximity ligation assay, acetyl-proteomics, SIRT1 deacetylase activity assay, neuron-specific LARP7 KO mice\",\n      \"journal\": \"Journal of neuroinflammation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — domain-mapped Co-IP with enzymatic activity assay and acetyl-proteomics identification of substrate sites, single lab\",\n      \"pmids\": [\"41351020\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In Drosophila, loss of Larp7 (ortholog) impairs locomotion and reduces axonal growth at neuromuscular junctions; Larp7 functions autonomously in motoneurons to promote axogenesis; reducing P-TEFb abundance partially rescues locomotion and axonal growth defects, placing Larp7 upstream of P-TEFb in transcriptional regulation of long, GC-rich promoter genes in motoneurons.\",\n      \"method\": \"Genetic deletion in Drosophila, locomotion assays, NMJ morphology analysis, genetic epistasis with P-TEFb reduction, transcriptomic analysis of mutant motoneurons\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis in vivo with transcriptomic characterization in orthologous Drosophila system, preprint not yet peer-reviewed\",\n      \"pmids\": [],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"LARP7 promotes replication fork slowing and RAD51-mediated replication fork reversal in response to agents that cause both replication and transcription stress (e.g., camptothecin, BET inhibitors), and supports homologous recombination at direct DSBs; this function is not required for HR in response to hydroxyurea (replication stress without transcription stress), indicating the mechanism is linked to LARP7's canonical 7SK-snRNP/Pol II regulatory function.\",\n      \"method\": \"LARP7 knockdown, DNA fiber assay (fork slowing), RAD51 recruitment assays, HR assays, epistasis with Pol II inhibition\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — defined phenotypes with partial mechanistic follow-up, preprint not peer-reviewed\",\n      \"pmids\": [],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"LARP7 interacts with STING in cardiomyocytes (particularly under high glucose conditions); high glucose causes LARP7 to translocate from the nucleus to the cytoplasm where it interacts with accumulated STING to inhibit STING degradation via the autophagy-lysosomal pathway, contributing to cardiac dysfunction.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence (subcellular localization), adenovirus-mediated knockdown/overexpression, STING inhibitor treatment\",\n      \"journal\": \"Frontiers in bioscience\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — single Co-IP with localization data but mechanistic pathway is partially characterized, single lab\",\n      \"pmids\": [\"39082350\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"LARP7 is required for meiotic sex chromosome inactivation (MSCI) in mice; in germline-specific Larp7-deficient spermatocytes, LARP7 normally localizes to the XY body; its absence leads to failure of sex chromosome transcriptional silencing, accumulation of H4K12ac and loss of H3K9me2 on XY chromatin, and arrest of spermatogenesis.\",\n      \"method\": \"Germline-specific Larp7 KO mice, immunofluorescence (XY body localization), histone modification analysis, transcriptional analysis of sex chromosome genes\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — conditional KO with direct localization and chromatin modification readouts establishing a new functional role, single lab\",\n      \"pmids\": [\"39637191\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Full-length Tetrahymena LARP7 protein p65 structure in telomerase was determined by cryo-EM combined with NMR; three previously unknown helices are identified (one in NTD that binds the La module, one extending RRM1, one preceding xRRM2) that stabilize p65-TER interactions; the extended La module interacts with four 3' terminal U nucleotides and additionally with the TER pseudoknot, stem 1, and 5' end.\",\n      \"method\": \"Cryo-EM focused classification, NMR spectroscopy (Tetrahymena ortholog p65)\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — cryo-EM structure combined with NMR, revealing new structural elements in LARP7 family member\",\n      \"pmids\": [\"37330293\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"LARP7 is a stable core component of the 7SK snRNP that binds the 3'-terminal U-rich tail and 3' hairpin of 7SK snRNA (via its La module and C-terminal xRRM domain) to protect 7SK from degradation and maintain its structure; this positions LARP7 as a constitutive scaffold that sequesters P-TEFb in a transcriptionally inactive complex by facilitating HEXIM1 binding, thereby acting as a negative regulator of RNA Pol II transcriptional elongation; beyond 7SK, LARP7 serves as a bridging factor that guides 2'-O-methylation of spliceosomal U6 snRNA by connecting U6 to box C/D snoRNPs, promotes early human telomerase RNA biogenesis and processing, and allosterically enhances SIRT1 deacetylase activity through direct protein-protein interaction (C-terminal domain of LARP7 with N-terminal domain of SIRT1), thereby regulating downstream substrates including p53, NF-κB, and NLRP3 to modulate senescence, inflammation, and cardiac function.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"LARP7 is a multifunctional RNA-binding protein that serves as a constitutive scaffold of the 7SK small nuclear ribonucleoprotein (snRNP), a negative regulator of RNA Polymerase II transcriptional elongation, and a bridging factor for RNA modification and telomerase biogenesis. Through its N-terminal La module and C-terminal xRRM domain, LARP7 binds the 3'-terminal U-rich tail and stem-loop 4 of 7SK snRNA, stabilizing 7SK levels and enabling sequestration of P-TEFb in an inactive complex; loss of LARP7 releases P-TEFb, enhancing Pol II Ser2 phosphorylation and transcription of target genes including EMT transcription factors and HIV-1 [PMID:18281698, PMID:18483487, PMID:25053741, PMID:29946027]. Independent of 7SK, LARP7 physically connects U6 snRNA to box C/D snoRNPs to guide 2'-O-methylation essential for proper pre-mRNA splicing, promotes early processing and nuclear retention of human telomerase RNA (hTR), and allosterically enhances SIRT1 deacetylase activity through direct C-terminal domain interaction, thereby modulating p53/NF-κB acetylation, inflammasome assembly, senescence, and cardiac function [PMID:32017898, PMID:32017896, PMID:39009594, PMID:34818543, PMID:33663221, PMID:41351020]. Loss-of-function mutations in LARP7 cause Alazami syndrome, associated with short telomeres and defective U6 2'-O-methylation [PMID:27766953, PMID:32017898].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Establishing LARP7 as a constitutive 7SK snRNP component resolved how 7SK RNA stability is maintained and linked LARP7 directly to P-TEFb regulation and Pol II transcriptional control.\",\n      \"evidence\": \"Glycerol gradient sedimentation, immunodepletion, siRNA knockdown with Tat transactivation and transcription reporter assays in human cells (two independent labs)\",\n      \"pmids\": [\"18281698\", \"18483487\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which LARP7 facilitates HEXIM1 and P-TEFb recruitment was unresolved\", \"Whether LARP7 has functions beyond 7SK was unknown\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Mapping LARP7's binding to the 7SK 3' hairpin and U-tail and showing this binding is a prerequisite for P-TEFb recruitment demonstrated that LARP7 is not merely a passive stabilizer but actively participates in RNP assembly.\",\n      \"evidence\": \"In vivo RNA-protein interaction assays with systematic 7SK RNA mutagenesis\",\n      \"pmids\": [\"23471002\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Atomic-resolution structural basis for LARP7-7SK interaction was not yet available\", \"How LARP7 binding triggers conformational changes enabling P-TEFb capture was unknown\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Crystal structures of the LARP7 La module bound to 7SK 3' uridines and the demonstration that N- and C-terminal domains jointly stabilize a closed 7SK structure provided the first atomic-level model of how LARP7 organizes the 7SK snRNP.\",\n      \"evidence\": \"X-ray crystallography, SAXS, binding and footprinting assays\",\n      \"pmids\": [\"25753663\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structure of the C-terminal xRRM bound to stem-loop 4 was not yet determined\", \"How the full-length protein engages the complete 7SK was modeled but not resolved\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Demonstrating that LARP7 depletion redistributes P-TEFb to super elongation complexes and upregulates EMT transcription factors established a concrete biological consequence—breast cancer invasion and metastasis—of 7SK/P-TEFb deregulation.\",\n      \"evidence\": \"siRNA knockdown and overexpression with invasion/migration assays and gene expression analysis in breast cancer cells\",\n      \"pmids\": [\"25053741\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether LARP7 loss is causal in human tumors versus a correlate was not established\", \"Contribution of non-7SK functions of LARP7 to the cancer phenotype was not assessed\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Zebrafish epistasis experiments placed Larp7 upstream of Cdk9/P-TEFb-mediated Pol II Ser2 phosphorylation in cardiomyocyte proliferation, extending the transcriptional control axis to cardiac development.\",\n      \"evidence\": \"Morpholino knockdown in zebrafish with epistasis analysis and Pol II CTD phosphorylation readouts\",\n      \"pmids\": [\"26542022\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Morpholino-based evidence in zebrafish; genetic mutant confirmation was not provided\", \"Mammalian cardiac relevance was not yet demonstrated\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Linking LARP7 to telomerase activity and demonstrating very short telomeres in Alazami syndrome patients expanded LARP7's functional repertoire beyond transcriptional regulation to telomere maintenance.\",\n      \"evidence\": \"siRNA knockdown with TRAP telomerase assay and telomere length measurement in human cells and patient lymphocytes\",\n      \"pmids\": [\"27766953\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct mechanism by which LARP7 supports human telomerase RNA (hTR) was unclear\", \"Whether the telomere defect is independent of 7SK-mediated transcription changes was not resolved\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"A high-resolution crystal structure of the human LARP7 xRRM bound to 7SK stem-loop 4, combined with NMR dynamics, completed the structural picture of how LARP7's two RNA-binding domains jointly recognize and stabilize 7SK snRNA.\",\n      \"evidence\": \"2.2 Å X-ray crystallography, NMR ¹³C spin relaxation, ITC, and mutagenesis\",\n      \"pmids\": [\"29946027\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full-length LARP7-7SK RNP structure remained unresolved\", \"How structural changes propagate to HEXIM1/P-TEFb recruitment was mechanistically undetermined\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Studies of fission yeast LARP7 orthologs (Lar7/Pof8) demonstrated that the conserved xRRM domain promotes telomerase RNA stability and TERT assembly, establishing an evolutionarily conserved function in telomerase biogenesis.\",\n      \"evidence\": \"Genetic deletion and domain mutagenesis with RNA-protein interaction and telomere localization assays in S. pombe\",\n      \"pmids\": [\"29422501\", \"29422503\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether human LARP7 uses the same xRRM-dependent mechanism for hTR was not directly shown\", \"How LARP7 transitions between 7SK and telomerase RNA targets was unknown\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identification of the Legionella effector AnkH as a nuclear interactor of LARP7 that partially disrupts 7SK snRNP assembly revealed that pathogens exploit LARP7-mediated transcriptional control for intracellular replication.\",\n      \"evidence\": \"Co-immunoprecipitation, crystal structure of AnkH, site-directed mutagenesis, and bacterial intracellular growth assays\",\n      \"pmids\": [\"31455655\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Precise mechanism by which AnkH disrupts LARP7-7SK contacts was not fully defined\", \"Whether additional host targets of AnkH contribute to the phenotype was not excluded\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Two concurrent studies demonstrated that LARP7 bridges U6 snRNA to box C/D snoRNPs for 2'-O-methylation, establishing a second major RNA chaperone function; LARP7 loss causes widespread splicing defects, and Alazami syndrome patients show defective U6 modification.\",\n      \"evidence\": \"Co-immunoprecipitation, RNA modification analysis, transcriptome-wide splicing analysis in human cells and patient samples; conditional KO mouse with domain-specific rescue\",\n      \"pmids\": [\"32017898\", \"32017896\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How LARP7 simultaneously manages 7SK and U6 RNA clients was not resolved\", \"Whether all Alazami syndrome pathology traces to U6 modification versus telomerase or P-TEFb defects was unclear\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Discovery that LARP7 allosterically activates SIRT1 deacetylase activity uncovered a direct protein-protein mechanism outside RNA biology, linking LARP7 loss to p53/NF-κB hyperacetylation, senescence, and heart failure; ATM-mediated ubiquitination of LARP7 creates a damage-responsive feedback loop.\",\n      \"evidence\": \"Cardiac-specific and global KO mice, SIRT1 enzymatic activity assays, acetylation analysis of p53/NF-κB, senescence assays, ATM inhibitor rescue\",\n      \"pmids\": [\"33663221\", \"34818543\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether SIRT1 activation by LARP7 is fully independent of 7SK/P-TEFb was not formally demonstrated\", \"Structural basis of the LARP7-SIRT1 interaction was not determined\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Cryo-EM/NMR structure of full-length Tetrahymena LARP7 (p65) in the telomerase complex revealed three previously unknown helices and expanded contacts with telomerase RNA beyond the 3' tail, providing the most complete structural view of how LARP7 family proteins organize a catalytic RNP.\",\n      \"evidence\": \"Cryo-EM focused classification and NMR spectroscopy of Tetrahymena p65 within telomerase\",\n      \"pmids\": [\"37330293\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Human LARP7 full-length structure in any RNP context remains undetermined\", \"Whether the additional helices are conserved in vertebrate LARP7 is untested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Biochemical dissection of human telomerase RNA biogenesis showed LARP7 and MePCE bind 3'-extended hTR precursors and promote their maturation and nuclear retention, directly explaining LARP7's role in telomerase activity and telomere maintenance.\",\n      \"evidence\": \"Biochemical fractionation, RNA binding assays, depletion experiments, and telomere length assays in human cells\",\n      \"pmids\": [\"39009594\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether LARP7 escorts hTR through specific nuclear compartments was not resolved\", \"Contribution of MePCE versus LARP7 to individual biogenesis steps was not fully disentangled\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"LARP7 was shown to be required for meiotic sex chromosome inactivation (MSCI), localizing to the XY body and maintaining repressive chromatin marks, revealing a chromatin-regulatory role during spermatogenesis.\",\n      \"evidence\": \"Germline-specific Larp7 KO mice, immunofluorescence, histone modification and transcriptional analysis\",\n      \"pmids\": [\"39637191\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether MSCI function depends on 7SK/P-TEFb sequestration or a distinct mechanism was not determined\", \"No direct biochemical link between LARP7 and the MSCI silencing machinery was established\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Discovery that LARP7 undergoes liquid-liquid phase separation upon HIV-1 infection, sequestering P-TEFb and Tat in condensates through IDR lysine residues, revealed a biophysical mechanism for LARP7's antiviral function.\",\n      \"evidence\": \"Live cell imaging, IDR lysine mutagenesis, Tat-mediated transcription assays\",\n      \"pmids\": [\"40113991\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether LARP7 phase separation occurs in non-HIV contexts was not explored\", \"In vivo relevance for HIV-1 latency control was not demonstrated\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Domain mapping of the LARP7-SIRT1 interaction (LARP7 C-terminal domain to SIRT1 N-terminal domain) and identification of NLRP3 K21/K22/K24 as SIRT1 deacetylation targets established a molecular pathway from LARP7 to inflammasome suppression and neuroprotection after ischemic stroke.\",\n      \"evidence\": \"Co-immunoprecipitation with domain deletions, proximity ligation assay, acetyl-proteomics, neuron-specific LARP7 KO mice\",\n      \"pmids\": [\"41351020\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural basis for allosteric SIRT1 activation by LARP7 C-terminal domain is unknown\", \"Whether LARP7 regulates other SIRT1 substrates genome-wide was not assessed\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include: the structure of human full-length LARP7 in any RNP context; how LARP7 partitions among its distinct RNA clients (7SK, U6, hTR); whether SIRT1 activation is mechanistically separable from 7SK/P-TEFb regulation; and the relative contributions of each LARP7 function to Alazami syndrome pathology.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No human full-length LARP7 structure in any RNP complex\", \"Client RNA partitioning mechanism unknown\", \"Relative disease contribution of individual LARP7 functions not deconvolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [0, 1, 2, 3, 5, 6, 7, 9, 10, 17, 24]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [11, 12, 19]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [9, 10]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 1, 13, 23]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [15, 22]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 1, 2, 4, 14]},\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [9, 10, 17]},\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [11, 12]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [8, 17]}\n    ],\n    \"complexes\": [\n      \"7SK snRNP\",\n      \"telomerase RNP\"\n    ],\n    \"partners\": [\n      \"MePCE\",\n      \"HEXIM1\",\n      \"CDK9\",\n      \"SIRT1\",\n      \"MCTS1\",\n      \"STING\",\n      \"SIRT6\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}