{"gene":"LARP7","run_date":"2026-06-10T02:59:49","timeline":{"discoveries":[{"year":2008,"finding":"LARP7 is a stable, constitutive component of the 7SK snRNP that binds 7SK RNA directly; immunodepletion of LARP7 co-depletes most 7SK RNA regardless of P-TEFb, HEXIM1, or hnRNP A1 association status. siRNA knockdown of LARP7 decreased steady-state 7SK levels, increased free P-TEFb, and increased Tat transactivation of the HIV-1 LTR.","method":"Glycerol gradient sedimentation, immunodepletion, siRNA knockdown with functional readouts (P-TEFb levels, HIV-1 LTR transactivation)","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal immunodepletion, gradient sedimentation, siRNA knockdown with multiple functional readouts; replicated by concurrent independent study (PMID:18483487)","pmids":["18281698"],"is_preprint":false},{"year":2008,"finding":"LARP7 binds the highly conserved 3'-terminal U-rich stretch of 7SK RNA and is an integral part of the 7SK RNP. Upon transcriptional stimulation, LARP7 remains associated with 7SK RNA while P-TEFb is released. RNAi-mediated reduction of LARP7 enhances transcription from cellular Pol II promoters and from a TAT-dependent HIV-1 promoter, identifying LARP7 as a negative transcriptional regulator acting through the 7SK RNP.","method":"RNA immunoprecipitation, RNAi knockdown, reporter transcription assays","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — RNA-protein interaction assay plus functional transcription readout; independently replicated by PMID:18281698","pmids":["18483487"],"is_preprint":false},{"year":2013,"finding":"In vivo RNA-protein interaction assays mapped the 7SK elements required for core snRNP assembly: MePCE interacts with the 5'-terminal G1-U4/U106-G111 helix-tail motif, while Larp7 binds the 3'-terminal hairpin and the following U-rich tail of 7SK. Binding of Larp7 to 7SK is a prerequisite for in vivo recruitment of P-TEFb, indicating Larp7 directly participates in P-TEFb regulation beyond merely stabilizing 7SK.","method":"In vivo RNA-protein interaction assays, deletion/mutation mapping","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 2 / Moderate — in vivo binding assays with systematic deletion mapping and functional epistasis for P-TEFb recruitment; single lab but multiple orthogonal approaches","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 reveals that the penultimate uridine is tethered by both domains. The RRM1 of LARP7 is smaller and more exposed than in canonical La protein. A second C-terminal RRM (xRRM) binds the apical loop of the 3' hairpin of 7SK while the N-terminal La module binds at its foot; together they stabilize 7SK in a closed structure joining 5'-end conserved sequences with the 3' hairpin foot.","method":"X-ray crystallography, binding assays, footprinting, small-angle X-ray scattering (SAXS)","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure combined with binding assays, footprinting, and SAXS; multiple orthogonal methods in a single rigorous study","pmids":["25753663"],"is_preprint":false},{"year":2014,"finding":"Decreased levels of LARP7 and 7SK snRNA redistribute P-TEFb to the transcriptionally active super elongation complex, resulting in P-TEFb activation and increased transcription of EMT transcription factors (Slug, FOXC2, ZEB2, Twist1), promoting breast cancer EMT, invasion, and metastasis.","method":"siRNA knockdown, gene expression analysis, invasion/migration assays, ChIP","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function with defined molecular mechanism (P-TEFb redistribution) and multiple downstream phenotypic readouts; single lab","pmids":["25053741"],"is_preprint":false},{"year":2018,"finding":"2.2-Å X-ray crystal structure of the human Larp7 xRRM bound to 7SK stem-loop 4 reveals a unique binding interface. The xRRM is preordered to bind a flexible RNA loop 4. Mutagenesis combined with isothermal titration calorimetry quantified the contribution of individual contacts. The La module and xRRM together define a structural model for Larp7 binding to the 7SK 3' end and mechanism for 7SK RNP assembly.","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 / Strong — high-resolution crystal structure with NMR dynamics and mutagenesis/ITC validation; multiple orthogonal methods in one rigorous study","pmids":["29946027"],"is_preprint":false},{"year":2018,"finding":"LARP7 family protein Lar7 (fission yeast ortholog) 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, remains a component of the mature telomerase complex, and is required for telomerase localization to the telomere.","method":"Genetic deletion, co-immunoprecipitation, RNA immunoprecipitation, telomere localization assays in S. pombe","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP and RNA-IP with genetic KO and functional localization readouts; fission yeast ortholog study, single lab","pmids":["29422501"],"is_preprint":false},{"year":2016,"finding":"Depletion of human LARP7 by siRNA reduced telomerase enzymatic activity and caused progressively shorter telomeres in human cancer cell lines, demonstrating a role for LARP7 in maintaining telomerase activity and telomere length in human cells.","method":"siRNA knockdown, TRAP telomerase activity assay, telomere length measurement","journal":"BMC genomics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct enzymatic activity assay plus telomere length measurement after LARP7 depletion; single lab","pmids":["27766953"],"is_preprint":false},{"year":2020,"finding":"LARP7 functions as a critical cofactor for 2'-O-methylation of U6 snRNA in mouse male germ cells by promoting U6 loading onto box C/D snoRNP. Ablation of LARP7 in the male germline causes defective U6 2'-O-methylation, massive alterations in pre-mRNA splicing, and spermatogenic failure; these defects were rescued by wild-type LARP7 but not by a U6-loading-deficient LARP7 mutant.","method":"Conditional knockout, rescue experiments with wild-type vs. mutant LARP7, 2'-O-methylation assays, RNA-seq splicing analysis","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — genetic KO with specific mechanistic rescue (mutant vs. wild-type), biochemical modification assays, and transcriptome-wide splicing readout; replicated by concurrent independent study (PMID:32017898)","pmids":["32017896"],"is_preprint":false},{"year":2020,"finding":"LARP7 physically connects spliceosomal U6 snRNA with a distinct subset of box C/D snoRNAs guiding U6 2'-O-methylation; depletion of LARP7 severely compromises these specific U6 2'-O-methylations and perturbs alternative splicing. Defects in U6 2'-O-methylation were also identified in Alazami syndrome patient cells carrying a LARP7 mutation.","method":"Co-immunoprecipitation, RNA immunoprecipitation, 2'-O-methylation profiling, RNA-seq, patient-derived cell analysis","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP establishing bridging function, biochemical modification assay, transcriptome analysis, and patient validation; replicated by concurrent independent study (PMID:32017896)","pmids":["32017898"],"is_preprint":false},{"year":2021,"finding":"Reactive oxygen species activate ATM, which triggers LARP7 ubiquitination and degradation in failing cardiomyocytes. Cardiac-specific LARP7 knockout causes defective mitochondrial biogenesis, impaired oxidative phosphorylation, elevated oxidative stress, and heart failure, accompanied by reduced SIRT1 stability and deacetylase activity that impairs SIRT1-mediated transcription of OXPHOS and energy metabolism genes.","method":"Cardiac-specific and global KO mice, AAV9-mediated overexpression, co-immunoprecipitation, ATM inhibitor pharmacology, ubiquitination assay","journal":"Circulation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO mouse with defined mitochondrial and SIRT1 phenotypes, plus ubiquitination assay and pharmacological rescue; single lab but multiple in vivo and biochemical methods","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 via increased acetylation, and accelerates cellular senescence. Deletion of LARP7 in rodents leads to senescent cell accumulation and premature aging.","method":"LARP7 knockout rodent model, acetylation assays, SIRT1 activity assay, co-immunoprecipitation, senescence markers","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo KO model plus biochemical SIRT1 activity and acetylation assays; single lab, multiple methods","pmids":["34818543"],"is_preprint":false},{"year":2019,"finding":"The Legionella effector AnkH interacts with nuclear LARP7 (component of the 7SK snRNP), partially impeding interactions of 7SK snRNP components with LARP7 and interfering with Pol II transcriptional elongation. A substitution in the β-hairpin loop of the third ankyrin repeat of AnkH diminishes LARP7-AnkH interaction and phenocopies the ankH null mutant defect in intracellular growth.","method":"Co-immunoprecipitation, crystal structure of AnkH, site-directed mutagenesis, LARP7 knockdown in host cells, bacterial intracellular growth assay","journal":"mBio","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP interaction, AnkH crystal structure, mutagenesis abolishing interaction with functional consequence; single lab","pmids":["31455655"],"is_preprint":false},{"year":2024,"finding":"LARP7 interacts with SIRT6 to maintain its expression; LARP7 depletion disrupts this interaction and decreases SIRT6 levels. Additionally, YTHDF2-mediated m6A-dependent degradation of Larp7 mRNA under combined cadmium/high-fat diet exposure reduces LARP7 protein, contributing to hippocampal neuronal senescence.","method":"Co-immunoprecipitation, RNA immunoprecipitation, siRNA knockdown, RNA stability assays, LARP7 overexpression","journal":"Journal of hazardous materials","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP for LARP7-SIRT6 interaction with limited mechanistic follow-up; single lab","pmids":["39002485"],"is_preprint":false},{"year":2024,"finding":"LARP7 and MePCE bind an early 3'-extended precursor form of human telomerase RNA (hTR); their depletion inhibits conversion of the 3'-extended short form into mature hTR and causes cytoplasmic accumulation of hTR and telomere shortening, placing LARP7/MePCE as positive factors in hTR maturation and processing.","method":"Biochemical fractionation, RNA immunoprecipitation, LARP7/MePCE depletion, telomere length assays, telomerase activity assays","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — RNA-IP with functional depletion, telomerase activity and telomere length readouts; single lab but multiple orthogonal approaches","pmids":["39009594"],"is_preprint":false},{"year":2022,"finding":"MCTS1 interacts with LARP7 (confirmed by Co-IP), predominantly in the cytoplasm. MCTS1 increases LARP7 protein half-life and reduces its poly-ubiquitination, stabilizing LARP7 protein via protection from proteasomal degradation.","method":"Co-immunoprecipitation, cycloheximide chase assay, ubiquitination Co-IP","journal":"Clinical and experimental pharmacology & physiology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP and CHX chase; single lab, limited mechanistic follow-up","pmids":["35274760"],"is_preprint":false},{"year":2024,"finding":"Under high-glucose conditions, LARP7 translocates from the nucleus to the cytoplasm where it interacts with accumulated STING protein to inhibit STING's degradation via the autophagy-lysosomal pathway, thereby promoting cardiomyocyte fibrosis and apoptosis in diabetic cardiomyopathy.","method":"Co-immunoprecipitation, subcellular fractionation/immunofluorescence, adenovirus-mediated knockdown/overexpression, autophagy flux assays","journal":"Frontiers in bioscience (Landmark edition)","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP for cytoplasmic LARP7-STING interaction with functional knockdown readout; single lab","pmids":["39082350"],"is_preprint":false},{"year":2025,"finding":"LARP7's C-terminal domain interacts with the N-terminal domain of SIRT1 to enhance SIRT1 deacetylase activity; SIRT1 then deacetylates NLRP3 at K21/K22/K24, inhibiting inflammasome assembly and neuronal pyroptosis after ischemic stroke.","method":"Co-immunoprecipitation, proximity ligation assay, domain deletion analysis, acetyl-proteomics, neuron-specific KO mice","journal":"Journal of neuroinflammation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — domain-mapping Co-IP, acetyl-proteomics identifying NLRP3 deacetylation sites, in vivo KO; single lab but multiple orthogonal methods","pmids":["41351020"],"is_preprint":false},{"year":2023,"finding":"Crystal structure (and NMR) of Tetrahymena p65 (LARP7 ortholog) with telomerase RNA reveals three previously unknown helices: one in the NTD binding the La module, one extending RRM1, and one preceding xRRM. The extended La module (αN, LaM, RRM1) interacts with four 3' terminal U nucleotides; LaM and αN additionally interact with TER pseudoknot, stem 1, and the 5' end, revealing extensive p65-TER contacts promoting TER folding and core RNP assembly.","method":"Cryo-EM focused classification, NMR spectroscopy, structural analysis","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — cryo-EM combined with NMR for full-length structure; Tetrahymena LARP7 ortholog p65 with direct relevance to LARP7 family mechanism; single lab","pmids":["37330293"],"is_preprint":false},{"year":2025,"finding":"HIV-1 infection triggers liquid-liquid phase separation of LARP7, forming condensates that sequester Tat. Conserved lysine residues in the intrinsically disordered region of LARP7 are essential for both phase separation and inhibition of Tat-mediated transcription, thereby restraining HIV-1 replication.","method":"Live-cell imaging of LARP7 condensates, site-directed mutagenesis of lysine residues, Tat-dependent transcription assays","journal":"EMBO reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — live imaging of phase separation with mutagenesis identifying essential residues and functional transcription readout; single lab","pmids":["40113991"],"is_preprint":false},{"year":2024,"finding":"LARP7 is required for meiotic sex chromosome inactivation (MSCI) in mouse spermatocytes. LARP7 localizes to the XY body in spermatocytes, and germline-specific Larp7 deletion results in spermatogenic arrest, persistent transcription of sex chromosome genes, accumulation of H4K12ac, and loss of H3K9me2 at the XY body, indicating a role in epigenetic chromatin silencing during meiosis.","method":"Germline-specific conditional KO, immunofluorescence localization, RNA-seq, ChIP for histone marks","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional KO with specific localization, transcriptional, and chromatin mark readouts; single lab","pmids":["39637191"],"is_preprint":false},{"year":2026,"finding":"LARP7 promotes G2/M phase transition in cardiomyocytes by suppressing p21 via the SIRT1/p53 pathway, thereby elevating CDK1/CCNB activity and extending the neonatal heart regenerative window. Co-expression of LARP7 with CCND1/CDK4 via dual AAV9 markedly boosted cardiac regeneration after injury.","method":"AAV9-mediated overexpression, cell cycle analysis, SIRT1/p53/p21/CDK1 pathway analysis, cardiac injury model","journal":"Journal of molecular and cellular cardiology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — gain-of-function with pathway analysis; limited mechanistic dissection of LARP7-SIRT1 direct interaction; single lab","pmids":["41667032"],"is_preprint":false},{"year":2025,"finding":"In Drosophila, loss of Larp7 or 7SK RNA impairs locomotion and reduces axonal growth at neuromuscular junctions. Larp7 functions autonomously in specific motoneurons to promote axogenesis. Reducing P-TEFb abundance partially rescues the locomotion and axonal growth defects, placing Larp7 upstream of P-TEFb in this transcriptional regulatory pathway in neurons.","method":"Genetic deletion in Drosophila, neuromuscular junction morphology analysis, locomotion assays, genetic epistasis with P-TEFb reduction, transcriptomic analysis of mutant motoneurons","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis in a model organism with multiple functional readouts; Drosophila LARP7 ortholog; preprint not yet peer-reviewed","pmids":[],"is_preprint":true},{"year":2025,"finding":"HEXIM1 and LARP7 promote 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 support homologous recombination at direct DSBs. This role is not required for HR in response to hydroxyurea (replication stress without transcription stress), and 7SK snRNP components are not recruited to stressed replication forks; RNA Pol II inhibition phenocopies their loss.","method":"siRNA knockdown of LARP7/HEXIM1, replication fork fiber assays, RAD51 foci quantification, HR reporter assays, Pol II inhibitor epistasis","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional KD with multiple orthogonal assays (fiber, foci, HR reporter) and epistasis with Pol II inhibition; preprint not yet peer-reviewed","pmids":[],"is_preprint":true}],"current_model":"LARP7 is a constitutive core component of the 7SK snRNP that binds the 3'-terminal U-rich tail and hairpin of 7SK RNA (via its La module and C-terminal xRRM) to stabilize 7SK and thereby sequester P-TEFb in a transcriptionally inactive complex, acting as a negative regulator of RNA Pol II elongation; it additionally functions as a bridging factor that loads U6 snRNA onto box C/D snoRNPs for 2'-O-methylation to ensure splicing fidelity, participates in telomerase RNA biogenesis and telomere maintenance, allosterically enhances SIRT1 deacetylase activity to regulate p53/NF-κB acetylation and senescence, undergoes ATM-triggered ubiquitination and degradation under DNA damage/oxidative stress, and can form liquid-liquid phase separation condensates that sequester P-TEFb and viral Tat to restrain HIV-1 transcription."},"narrative":{"mechanistic_narrative":"LARP7 is a constitutive core component of the 7SK small nuclear ribonucleoprotein (snRNP) that functions as a negative regulator of RNA polymerase II transcriptional elongation by sequestering the positive elongation factor P-TEFb [PMID:18281698, PMID:18483487]. It binds 7SK RNA directly through its La module (La motif plus RRM1), which tethers the 3'-terminal uridines, and a C-terminal extended RRM (xRRM) that clamps the apical loop of the 3' hairpin; together these contacts close 7SK into a stable conformation that joins the 5' and 3' ends and is a prerequisite for in vivo P-TEFb recruitment [PMID:23471002, PMID:25753663, PMID:29946027]. Loss of LARP7 destabilizes 7SK, redistributes P-TEFb into the active super elongation complex, and elevates transcription—including Tat-dependent HIV-1 transcription and EMT-driving transcription factors that promote breast cancer invasion [PMID:18281698, PMID:25053741]. Beyond elongation control, LARP7 acts as a bridging factor that loads spliceosomal U6 snRNA onto box C/D snoRNPs to direct U6 2'-O-methylation, ensuring splicing fidelity; ablation in the male germline causes defective U6 methylation, widespread splicing errors, and spermatogenic failure, and U6 methylation defects are seen in Alazami syndrome patient cells carrying a LARP7 mutation [PMID:32017896, PMID:32017898]. LARP7 also participates in telomerase RNA biogenesis, binding and protecting telomerase RNA precursors to support maturation, telomerase activity, and telomere length [PMID:27766953, PMID:39009594]. A distinct activity is allosteric enhancement of SIRT1 deacetylase activity through a C-terminal/SIRT1 N-terminal interaction, modulating acetylation of p53, NF-κB, and NLRP3 to control senescence and inflammasome-driven pyroptosis [PMID:34818543, PMID:41351020]. Under DNA damage and oxidative stress, ATM activation triggers LARP7 ubiquitination and degradation, linking its loss to senescence, premature aging, and cardiac dysfunction [PMID:33663221, PMID:34818543]. LARP7 can also undergo liquid-liquid phase separation upon HIV-1 infection, forming condensates that sequester Tat to restrain viral transcription [PMID:40113991].","teleology":[{"year":2008,"claim":"Established LARP7 as a bona fide, constitutive subunit of the 7SK snRNP and a negative regulator of Pol II elongation, answering whether 7SK stability and P-TEFb sequestration depend on a dedicated protein.","evidence":"Glycerol gradient sedimentation, reciprocal immunodepletion, RNA-IP, and siRNA knockdown with P-TEFb and HIV-1 LTR transactivation readouts in human cells","pmids":["18281698","18483487"],"confidence":"High","gaps":["Did not resolve the RNA elements or domains mediating binding","Mechanism by which LARP7 stabilizes 7SK left structural"]},{"year":2013,"claim":"Mapped the 7SK architecture of core snRNP assembly and showed LARP7 binding is upstream of P-TEFb recruitment, distinguishing an active assembly role from passive 7SK stabilization.","evidence":"In vivo RNA-protein interaction assays with deletion/mutation mapping and functional epistasis for P-TEFb recruitment","pmids":["23471002"],"confidence":"High","gaps":["Atomic-resolution view of LARP7-7SK contacts not yet available","How MePCE and LARP7 cooperate structurally unresolved"]},{"year":2015,"claim":"Provided the structural basis for LARP7 recognition of 7SK, showing the La module tethers the 3' uridines and the xRRM clamps the 3' hairpin to close 7SK into a stable conformation.","evidence":"X-ray crystallography of the La module bound to 7SK 3' uridines, with footprinting and SAXS","pmids":["25753663"],"confidence":"High","gaps":["High-resolution xRRM-RNA interface not yet captured","Dynamics of the closed conformation not addressed"]},{"year":2016,"claim":"Extended LARP7 function to telomere biology by linking it to telomerase enzymatic activity and telomere length maintenance in human cells.","evidence":"siRNA knockdown with TRAP telomerase activity assay and telomere length measurement in cancer cell lines","pmids":["27766953"],"confidence":"Medium","gaps":["Direct binding to human telomerase RNA not demonstrated here","Step in telomerase biogenesis affected unresolved"]},{"year":2018,"claim":"Defined the high-resolution xRRM-7SK stem-loop 4 interface and the conserved telomerase-RNA-binding role of the LARP7 family, unifying 7SK and telomerase RNA recognition mechanisms.","evidence":"2.2-Å crystallography, NMR dynamics and ITC for human xRRM; genetic deletion and Co-IP/RNA-IP for the fission yeast ortholog Lar7","pmids":["29946027","29422501"],"confidence":"High","gaps":["Human telomerase complex structure not solved","How a single protein discriminates 7SK versus telomerase RNA in cells unclear"]},{"year":2020,"claim":"Revealed a 7SK-independent function: LARP7 bridges U6 snRNA to box C/D snoRNPs to direct U6 2'-O-methylation, establishing a role in splicing fidelity and connecting it to human disease.","evidence":"Conditional germline knockout with wild-type versus U6-loading-deficient rescue, 2'-O-methylation assays, RNA-seq splicing analysis, and Alazami syndrome patient cell analysis","pmids":["32017896","32017898"],"confidence":"High","gaps":["Whether U6 loading and 7SK binding are mutually exclusive states unresolved","Mechanism of snoRNA subset selection not defined"]},{"year":2021,"claim":"Connected LARP7 stability to stress signaling, showing ATM-triggered ubiquitination and degradation of LARP7 dampens SIRT1 activity to drive senescence, aging, and cardiac failure.","evidence":"Cardiac-specific and global KO mice, AAV9 overexpression, ubiquitination assays, ATM inhibitor pharmacology, SIRT1 activity and acetylation assays","pmids":["33663221","34818543"],"confidence":"Medium","gaps":["E3 ligase mediating LARP7 ubiquitination not identified","Whether SIRT1 regulation is independent of 7SK function unclear"]},{"year":2024,"claim":"Refined LARP7's telomerase role to RNA precursor maturation, placing LARP7/MePCE as positive factors converting 3'-extended hTR into mature RNA.","evidence":"Biochemical fractionation, RNA-IP, LARP7/MePCE depletion, telomerase activity and telomere length assays","pmids":["39009594"],"confidence":"Medium","gaps":["Enzymatic steps of hTR 3' processing not resolved","Coordination with nuclear/cytoplasmic trafficking unclear"]},{"year":2024,"claim":"Identified a meiotic chromatin-silencing function, showing LARP7 localizes to the XY body and is required for meiotic sex chromosome inactivation in spermatocytes.","evidence":"Germline-specific conditional KO, immunofluorescence localization, RNA-seq, and ChIP for histone marks in mouse spermatocytes","pmids":["39637191"],"confidence":"Medium","gaps":["Whether MSCI role reflects 7SK/elongation control or a distinct mechanism unresolved","Direct chromatin recruitment mechanism unknown"]},{"year":2025,"claim":"Resolved a mechanism for direct viral restraint, showing LARP7 phase separates upon HIV-1 infection to sequester Tat via IDR lysines.","evidence":"Live-cell imaging of condensates, lysine mutagenesis, and Tat-dependent transcription assays","pmids":["40113991"],"confidence":"Medium","gaps":["Trigger linking infection to phase separation not defined","Relationship between condensate and canonical 7SK snRNP unclear"]},{"year":2025,"claim":"Defined the LARP7-SIRT1 interaction at domain resolution and a downstream NLRP3 deacetylation axis controlling inflammasome activation.","evidence":"Domain-mapping Co-IP, proximity ligation, acetyl-proteomics mapping NLRP3 sites, and neuron-specific KO mice after ischemic stroke","pmids":["41351020"],"confidence":"Medium","gaps":["Structural basis of allosteric SIRT1 enhancement not solved","Whether this is independent of nuclear 7SK functions unresolved"]},{"year":null,"claim":"How LARP7 partitions among its distinct roles—7SK/P-TEFb control, U6 methylation, telomerase maturation, SIRT1 modulation, and phase separation—within a cell, and what determines which function dominates in a given context, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model integrating nuclear RNP roles with cytoplasmic SIRT-axis functions","Regulatory switches between functions not identified","Structural basis of SIRT1 enhancement and condensate assembly not determined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[0,1,2,3,5]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[8,9]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[11,17]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0,1,4]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[12,16]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[15,16]},{"term_id":"GO:0000228","term_label":"nuclear chromosome","supporting_discovery_ids":[20]}],"pathway":[{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,1,2]},{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[8,9,14]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[9,19]}],"complexes":["7SK snRNP","telomerase complex"],"partners":["MEPCE","P-TEFB","SIRT1","HEXIM1","SIRT6","MCTS1","STING"],"other_free_text":[]}},"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). U6 snRNA processing is required for spermatogenesis (By similarity)","subcellular_location":"Nucleus, nucleoplasm","url":"https://www.uniprot.org/uniprotkb/Q4G0J3/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/LARP7","classification":"Not Classified","n_dependent_lines":89,"n_total_lines":1208,"dependency_fraction":0.07367549668874172},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000174720","cell_line_id":"CID000806","localizations":[{"compartment":"nucleolus_gc","grade":3},{"compartment":"nucleoplasm","grade":3},{"compartment":"nuclear_punctae","grade":1},{"compartment":"vesicles","grade":1}],"interactors":[{"gene":"CDK9","stoichiometry":10.0},{"gene":"MEPCE","stoichiometry":10.0},{"gene":"CCNT1","stoichiometry":10.0},{"gene":"HEXIM1","stoichiometry":10.0},{"gene":"CPSF6","stoichiometry":0.2},{"gene":"DDOST","stoichiometry":0.2},{"gene":"DDX21","stoichiometry":0.2},{"gene":"DHX9","stoichiometry":0.2},{"gene":"DRG1","stoichiometry":0.2},{"gene":"HNRNPA2B1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID000806","total_profiled":1310},"omim":[{"mim_id":"618657","title":"La RIBONUCLEOPROTEIN 4; 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2008,\n      \"finding\": \"LARP7 is a stable, constitutive component of the 7SK snRNP that binds 7SK RNA directly; immunodepletion of LARP7 co-depletes most 7SK RNA regardless of P-TEFb, HEXIM1, or hnRNP A1 association status. siRNA knockdown of LARP7 decreased steady-state 7SK levels, increased free P-TEFb, and increased Tat transactivation of the HIV-1 LTR.\",\n      \"method\": \"Glycerol gradient sedimentation, immunodepletion, siRNA knockdown with functional readouts (P-TEFb levels, HIV-1 LTR transactivation)\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal immunodepletion, gradient sedimentation, siRNA knockdown with multiple functional readouts; replicated by concurrent independent study (PMID:18483487)\",\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 and is an integral part of the 7SK RNP. Upon transcriptional stimulation, LARP7 remains associated with 7SK RNA while P-TEFb is released. RNAi-mediated reduction of LARP7 enhances transcription from cellular Pol II promoters and from a TAT-dependent HIV-1 promoter, identifying LARP7 as a negative transcriptional regulator acting through the 7SK RNP.\",\n      \"method\": \"RNA immunoprecipitation, RNAi knockdown, reporter transcription assays\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — RNA-protein interaction assay plus functional transcription readout; independently replicated by PMID:18281698\",\n      \"pmids\": [\"18483487\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"In vivo RNA-protein interaction assays mapped the 7SK elements required for core snRNP assembly: MePCE interacts with the 5'-terminal G1-U4/U106-G111 helix-tail motif, while Larp7 binds the 3'-terminal hairpin and the following U-rich tail of 7SK. Binding of Larp7 to 7SK is a prerequisite for in vivo recruitment of P-TEFb, indicating Larp7 directly participates in P-TEFb regulation beyond merely stabilizing 7SK.\",\n      \"method\": \"In vivo RNA-protein interaction assays, deletion/mutation mapping\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo binding assays with systematic deletion mapping and functional epistasis for P-TEFb recruitment; single lab but multiple orthogonal approaches\",\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 reveals that the penultimate uridine is tethered by both domains. The RRM1 of LARP7 is smaller and more exposed than in canonical La protein. A second C-terminal RRM (xRRM) binds the apical loop of the 3' hairpin of 7SK while the N-terminal La module binds at its foot; together they stabilize 7SK in a closed structure joining 5'-end conserved sequences with the 3' hairpin foot.\",\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 / Strong — crystal structure combined with binding assays, footprinting, and SAXS; multiple orthogonal methods in a single rigorous study\",\n      \"pmids\": [\"25753663\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Decreased levels of LARP7 and 7SK snRNA redistribute P-TEFb to the transcriptionally active super elongation complex, resulting in P-TEFb activation and increased transcription of EMT transcription factors (Slug, FOXC2, ZEB2, Twist1), promoting breast cancer EMT, invasion, and metastasis.\",\n      \"method\": \"siRNA knockdown, gene expression analysis, invasion/migration assays, ChIP\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function with defined molecular mechanism (P-TEFb redistribution) and multiple downstream phenotypic readouts; single lab\",\n      \"pmids\": [\"25053741\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"2.2-Å X-ray crystal structure of the human Larp7 xRRM bound to 7SK stem-loop 4 reveals a unique binding interface. The xRRM is preordered to bind a flexible RNA loop 4. Mutagenesis combined with isothermal titration calorimetry quantified the contribution of individual contacts. The La module and xRRM together define a structural model for Larp7 binding to the 7SK 3' end and mechanism for 7SK RNP assembly.\",\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 / Strong — high-resolution crystal structure with NMR dynamics and mutagenesis/ITC validation; multiple orthogonal methods in one rigorous study\",\n      \"pmids\": [\"29946027\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"LARP7 family protein Lar7 (fission yeast ortholog) 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, remains a component of the mature telomerase complex, and is required for telomerase localization to the telomere.\",\n      \"method\": \"Genetic deletion, co-immunoprecipitation, RNA immunoprecipitation, telomere localization assays in S. pombe\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP and RNA-IP with genetic KO and functional localization readouts; fission yeast ortholog study, single lab\",\n      \"pmids\": [\"29422501\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Depletion of human LARP7 by siRNA reduced telomerase enzymatic activity and caused progressively shorter telomeres in human cancer cell lines, demonstrating a role for LARP7 in maintaining telomerase activity and telomere length in human cells.\",\n      \"method\": \"siRNA knockdown, TRAP telomerase activity assay, telomere length measurement\",\n      \"journal\": \"BMC genomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct enzymatic activity assay plus telomere length measurement after LARP7 depletion; single lab\",\n      \"pmids\": [\"27766953\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"LARP7 functions as a critical cofactor for 2'-O-methylation of U6 snRNA in mouse male germ cells by promoting U6 loading onto box C/D snoRNP. Ablation of LARP7 in the male germline causes defective U6 2'-O-methylation, massive alterations in pre-mRNA splicing, and spermatogenic failure; these defects were rescued by wild-type LARP7 but not by a U6-loading-deficient LARP7 mutant.\",\n      \"method\": \"Conditional knockout, rescue experiments with wild-type vs. mutant LARP7, 2'-O-methylation assays, RNA-seq splicing analysis\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — genetic KO with specific mechanistic rescue (mutant vs. wild-type), biochemical modification assays, and transcriptome-wide splicing readout; replicated by concurrent independent study (PMID:32017898)\",\n      \"pmids\": [\"32017896\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"LARP7 physically connects spliceosomal U6 snRNA with a distinct subset of box C/D snoRNAs guiding U6 2'-O-methylation; depletion of LARP7 severely compromises these specific U6 2'-O-methylations and perturbs alternative splicing. Defects in U6 2'-O-methylation were also identified in Alazami syndrome patient cells carrying a LARP7 mutation.\",\n      \"method\": \"Co-immunoprecipitation, RNA immunoprecipitation, 2'-O-methylation profiling, RNA-seq, patient-derived cell analysis\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP establishing bridging function, biochemical modification assay, transcriptome analysis, and patient validation; replicated by concurrent independent study (PMID:32017896)\",\n      \"pmids\": [\"32017898\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Reactive oxygen species activate ATM, which triggers LARP7 ubiquitination and degradation in failing cardiomyocytes. Cardiac-specific LARP7 knockout causes defective mitochondrial biogenesis, impaired oxidative phosphorylation, elevated oxidative stress, and heart failure, accompanied by reduced SIRT1 stability and deacetylase activity that impairs SIRT1-mediated transcription of OXPHOS and energy metabolism genes.\",\n      \"method\": \"Cardiac-specific and global KO mice, AAV9-mediated overexpression, co-immunoprecipitation, ATM inhibitor pharmacology, ubiquitination assay\",\n      \"journal\": \"Circulation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO mouse with defined mitochondrial and SIRT1 phenotypes, plus ubiquitination assay and pharmacological rescue; single lab but multiple in vivo and biochemical methods\",\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 via increased acetylation, and accelerates cellular senescence. Deletion of LARP7 in rodents leads to senescent cell accumulation and premature aging.\",\n      \"method\": \"LARP7 knockout rodent model, acetylation assays, SIRT1 activity assay, co-immunoprecipitation, senescence markers\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo KO model plus biochemical SIRT1 activity and acetylation assays; single lab, multiple methods\",\n      \"pmids\": [\"34818543\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"The Legionella effector AnkH interacts with nuclear LARP7 (component of the 7SK snRNP), partially impeding interactions of 7SK snRNP components with LARP7 and interfering with Pol II transcriptional elongation. A substitution in the β-hairpin loop of the third ankyrin repeat of AnkH diminishes LARP7-AnkH interaction and phenocopies the ankH null mutant defect in intracellular growth.\",\n      \"method\": \"Co-immunoprecipitation, crystal structure of AnkH, site-directed mutagenesis, LARP7 knockdown in host cells, bacterial intracellular growth assay\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP interaction, AnkH crystal structure, mutagenesis abolishing interaction with functional consequence; single lab\",\n      \"pmids\": [\"31455655\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"LARP7 interacts with SIRT6 to maintain its expression; LARP7 depletion disrupts this interaction and decreases SIRT6 levels. Additionally, YTHDF2-mediated m6A-dependent degradation of Larp7 mRNA under combined cadmium/high-fat diet exposure reduces LARP7 protein, contributing to hippocampal neuronal senescence.\",\n      \"method\": \"Co-immunoprecipitation, RNA immunoprecipitation, siRNA knockdown, RNA stability assays, LARP7 overexpression\",\n      \"journal\": \"Journal of hazardous materials\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP for LARP7-SIRT6 interaction with limited mechanistic follow-up; single lab\",\n      \"pmids\": [\"39002485\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"LARP7 and MePCE bind an early 3'-extended precursor form of human telomerase RNA (hTR); their depletion inhibits conversion of the 3'-extended short form into mature hTR and causes cytoplasmic accumulation of hTR and telomere shortening, placing LARP7/MePCE as positive factors in hTR maturation and processing.\",\n      \"method\": \"Biochemical fractionation, RNA immunoprecipitation, LARP7/MePCE depletion, telomere length assays, telomerase activity assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RNA-IP with functional depletion, telomerase activity and telomere length readouts; single lab but multiple orthogonal approaches\",\n      \"pmids\": [\"39009594\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"MCTS1 interacts with LARP7 (confirmed by Co-IP), predominantly in the cytoplasm. MCTS1 increases LARP7 protein half-life and reduces its poly-ubiquitination, stabilizing LARP7 protein via protection from proteasomal degradation.\",\n      \"method\": \"Co-immunoprecipitation, cycloheximide chase assay, ubiquitination Co-IP\",\n      \"journal\": \"Clinical and experimental pharmacology & physiology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP and CHX chase; single lab, limited mechanistic follow-up\",\n      \"pmids\": [\"35274760\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Under high-glucose conditions, LARP7 translocates from the nucleus to the cytoplasm where it interacts with accumulated STING protein to inhibit STING's degradation via the autophagy-lysosomal pathway, thereby promoting cardiomyocyte fibrosis and apoptosis in diabetic cardiomyopathy.\",\n      \"method\": \"Co-immunoprecipitation, subcellular fractionation/immunofluorescence, adenovirus-mediated knockdown/overexpression, autophagy flux assays\",\n      \"journal\": \"Frontiers in bioscience (Landmark edition)\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP for cytoplasmic LARP7-STING interaction with functional knockdown readout; single lab\",\n      \"pmids\": [\"39082350\"],\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; SIRT1 then deacetylates NLRP3 at K21/K22/K24, inhibiting inflammasome assembly and neuronal pyroptosis after ischemic stroke.\",\n      \"method\": \"Co-immunoprecipitation, proximity ligation assay, domain deletion analysis, acetyl-proteomics, neuron-specific KO mice\",\n      \"journal\": \"Journal of neuroinflammation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — domain-mapping Co-IP, acetyl-proteomics identifying NLRP3 deacetylation sites, in vivo KO; single lab but multiple orthogonal methods\",\n      \"pmids\": [\"41351020\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Crystal structure (and NMR) of Tetrahymena p65 (LARP7 ortholog) with telomerase RNA reveals three previously unknown helices: one in the NTD binding the La module, one extending RRM1, and one preceding xRRM. The extended La module (αN, LaM, RRM1) interacts with four 3' terminal U nucleotides; LaM and αN additionally interact with TER pseudoknot, stem 1, and the 5' end, revealing extensive p65-TER contacts promoting TER folding and core RNP assembly.\",\n      \"method\": \"Cryo-EM focused classification, NMR spectroscopy, structural analysis\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — cryo-EM combined with NMR for full-length structure; Tetrahymena LARP7 ortholog p65 with direct relevance to LARP7 family mechanism; single lab\",\n      \"pmids\": [\"37330293\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"HIV-1 infection triggers liquid-liquid phase separation of LARP7, forming condensates that sequester Tat. Conserved lysine residues in the intrinsically disordered region of LARP7 are essential for both phase separation and inhibition of Tat-mediated transcription, thereby restraining HIV-1 replication.\",\n      \"method\": \"Live-cell imaging of LARP7 condensates, site-directed mutagenesis of lysine residues, Tat-dependent transcription assays\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — live imaging of phase separation with mutagenesis identifying essential residues and functional transcription readout; single lab\",\n      \"pmids\": [\"40113991\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"LARP7 is required for meiotic sex chromosome inactivation (MSCI) in mouse spermatocytes. LARP7 localizes to the XY body in spermatocytes, and germline-specific Larp7 deletion results in spermatogenic arrest, persistent transcription of sex chromosome genes, accumulation of H4K12ac, and loss of H3K9me2 at the XY body, indicating a role in epigenetic chromatin silencing during meiosis.\",\n      \"method\": \"Germline-specific conditional KO, immunofluorescence localization, RNA-seq, ChIP for histone marks\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional KO with specific localization, transcriptional, and chromatin mark readouts; single lab\",\n      \"pmids\": [\"39637191\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"LARP7 promotes G2/M phase transition in cardiomyocytes by suppressing p21 via the SIRT1/p53 pathway, thereby elevating CDK1/CCNB activity and extending the neonatal heart regenerative window. Co-expression of LARP7 with CCND1/CDK4 via dual AAV9 markedly boosted cardiac regeneration after injury.\",\n      \"method\": \"AAV9-mediated overexpression, cell cycle analysis, SIRT1/p53/p21/CDK1 pathway analysis, cardiac injury model\",\n      \"journal\": \"Journal of molecular and cellular cardiology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — gain-of-function with pathway analysis; limited mechanistic dissection of LARP7-SIRT1 direct interaction; single lab\",\n      \"pmids\": [\"41667032\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In Drosophila, loss of Larp7 or 7SK RNA impairs locomotion and reduces axonal growth at neuromuscular junctions. Larp7 functions autonomously in specific motoneurons to promote axogenesis. Reducing P-TEFb abundance partially rescues the locomotion and axonal growth defects, placing Larp7 upstream of P-TEFb in this transcriptional regulatory pathway in neurons.\",\n      \"method\": \"Genetic deletion in Drosophila, neuromuscular junction morphology analysis, locomotion assays, genetic epistasis with P-TEFb reduction, transcriptomic analysis of mutant motoneurons\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis in a model organism with multiple functional readouts; Drosophila LARP7 ortholog; preprint not yet peer-reviewed\",\n      \"pmids\": [],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"HEXIM1 and LARP7 promote 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 support homologous recombination at direct DSBs. This role is not required for HR in response to hydroxyurea (replication stress without transcription stress), and 7SK snRNP components are not recruited to stressed replication forks; RNA Pol II inhibition phenocopies their loss.\",\n      \"method\": \"siRNA knockdown of LARP7/HEXIM1, replication fork fiber assays, RAD51 foci quantification, HR reporter assays, Pol II inhibitor epistasis\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional KD with multiple orthogonal assays (fiber, foci, HR reporter) and epistasis with Pol II inhibition; preprint not yet peer-reviewed\",\n      \"pmids\": [],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"LARP7 is a constitutive core component of the 7SK snRNP that binds the 3'-terminal U-rich tail and hairpin of 7SK RNA (via its La module and C-terminal xRRM) to stabilize 7SK and thereby sequester P-TEFb in a transcriptionally inactive complex, acting as a negative regulator of RNA Pol II elongation; it additionally functions as a bridging factor that loads U6 snRNA onto box C/D snoRNPs for 2'-O-methylation to ensure splicing fidelity, participates in telomerase RNA biogenesis and telomere maintenance, allosterically enhances SIRT1 deacetylase activity to regulate p53/NF-κB acetylation and senescence, undergoes ATM-triggered ubiquitination and degradation under DNA damage/oxidative stress, and can form liquid-liquid phase separation condensates that sequester P-TEFb and viral Tat to restrain HIV-1 transcription.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"LARP7 is a constitutive core component of the 7SK small nuclear ribonucleoprotein (snRNP) that functions as a negative regulator of RNA polymerase II transcriptional elongation by sequestering the positive elongation factor P-TEFb [#0, #1]. It binds 7SK RNA directly through its La module (La motif plus RRM1), which tethers the 3'-terminal uridines, and a C-terminal extended RRM (xRRM) that clamps the apical loop of the 3' hairpin; together these contacts close 7SK into a stable conformation that joins the 5' and 3' ends and is a prerequisite for in vivo P-TEFb recruitment [#2, #3, #5]. Loss of LARP7 destabilizes 7SK, redistributes P-TEFb into the active super elongation complex, and elevates transcription—including Tat-dependent HIV-1 transcription and EMT-driving transcription factors that promote breast cancer invasion [#0, #4]. Beyond elongation control, LARP7 acts as a bridging factor that loads spliceosomal U6 snRNA onto box C/D snoRNPs to direct U6 2'-O-methylation, ensuring splicing fidelity; ablation in the male germline causes defective U6 methylation, widespread splicing errors, and spermatogenic failure, and U6 methylation defects are seen in Alazami syndrome patient cells carrying a LARP7 mutation [#8, #9]. LARP7 also participates in telomerase RNA biogenesis, binding and protecting telomerase RNA precursors to support maturation, telomerase activity, and telomere length [#7, #14]. A distinct activity is allosteric enhancement of SIRT1 deacetylase activity through a C-terminal/SIRT1 N-terminal interaction, modulating acetylation of p53, NF-\\u03baB, and NLRP3 to control senescence and inflammasome-driven pyroptosis [#11, #17]. Under DNA damage and oxidative stress, ATM activation triggers LARP7 ubiquitination and degradation, linking its loss to senescence, premature aging, and cardiac dysfunction [#10, #11]. LARP7 can also undergo liquid-liquid phase separation upon HIV-1 infection, forming condensates that sequester Tat to restrain viral transcription [#19].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Established LARP7 as a bona fide, constitutive subunit of the 7SK snRNP and a negative regulator of Pol II elongation, answering whether 7SK stability and P-TEFb sequestration depend on a dedicated protein.\",\n      \"evidence\": \"Glycerol gradient sedimentation, reciprocal immunodepletion, RNA-IP, and siRNA knockdown with P-TEFb and HIV-1 LTR transactivation readouts in human cells\",\n      \"pmids\": [\"18281698\", \"18483487\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve the RNA elements or domains mediating binding\", \"Mechanism by which LARP7 stabilizes 7SK left structural\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Mapped the 7SK architecture of core snRNP assembly and showed LARP7 binding is upstream of P-TEFb recruitment, distinguishing an active assembly role from passive 7SK stabilization.\",\n      \"evidence\": \"In vivo RNA-protein interaction assays with deletion/mutation mapping and functional epistasis for P-TEFb recruitment\",\n      \"pmids\": [\"23471002\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Atomic-resolution view of LARP7-7SK contacts not yet available\", \"How MePCE and LARP7 cooperate structurally unresolved\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Provided the structural basis for LARP7 recognition of 7SK, showing the La module tethers the 3' uridines and the xRRM clamps the 3' hairpin to close 7SK into a stable conformation.\",\n      \"evidence\": \"X-ray crystallography of the La module bound to 7SK 3' uridines, with footprinting and SAXS\",\n      \"pmids\": [\"25753663\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"High-resolution xRRM-RNA interface not yet captured\", \"Dynamics of the closed conformation not addressed\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Extended LARP7 function to telomere biology by linking it to telomerase enzymatic activity and telomere length maintenance in human cells.\",\n      \"evidence\": \"siRNA knockdown with TRAP telomerase activity assay and telomere length measurement in cancer cell lines\",\n      \"pmids\": [\"27766953\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct binding to human telomerase RNA not demonstrated here\", \"Step in telomerase biogenesis affected unresolved\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Defined the high-resolution xRRM-7SK stem-loop 4 interface and the conserved telomerase-RNA-binding role of the LARP7 family, unifying 7SK and telomerase RNA recognition mechanisms.\",\n      \"evidence\": \"2.2-\\u00c5 crystallography, NMR dynamics and ITC for human xRRM; genetic deletion and Co-IP/RNA-IP for the fission yeast ortholog Lar7\",\n      \"pmids\": [\"29946027\", \"29422501\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Human telomerase complex structure not solved\", \"How a single protein discriminates 7SK versus telomerase RNA in cells unclear\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Revealed a 7SK-independent function: LARP7 bridges U6 snRNA to box C/D snoRNPs to direct U6 2'-O-methylation, establishing a role in splicing fidelity and connecting it to human disease.\",\n      \"evidence\": \"Conditional germline knockout with wild-type versus U6-loading-deficient rescue, 2'-O-methylation assays, RNA-seq splicing analysis, and Alazami syndrome patient cell analysis\",\n      \"pmids\": [\"32017896\", \"32017898\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether U6 loading and 7SK binding are mutually exclusive states unresolved\", \"Mechanism of snoRNA subset selection not defined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Connected LARP7 stability to stress signaling, showing ATM-triggered ubiquitination and degradation of LARP7 dampens SIRT1 activity to drive senescence, aging, and cardiac failure.\",\n      \"evidence\": \"Cardiac-specific and global KO mice, AAV9 overexpression, ubiquitination assays, ATM inhibitor pharmacology, SIRT1 activity and acetylation assays\",\n      \"pmids\": [\"33663221\", \"34818543\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"E3 ligase mediating LARP7 ubiquitination not identified\", \"Whether SIRT1 regulation is independent of 7SK function unclear\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Refined LARP7's telomerase role to RNA precursor maturation, placing LARP7/MePCE as positive factors converting 3'-extended hTR into mature RNA.\",\n      \"evidence\": \"Biochemical fractionation, RNA-IP, LARP7/MePCE depletion, telomerase activity and telomere length assays\",\n      \"pmids\": [\"39009594\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Enzymatic steps of hTR 3' processing not resolved\", \"Coordination with nuclear/cytoplasmic trafficking unclear\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identified a meiotic chromatin-silencing function, showing LARP7 localizes to the XY body and is required for meiotic sex chromosome inactivation in spermatocytes.\",\n      \"evidence\": \"Germline-specific conditional KO, immunofluorescence localization, RNA-seq, and ChIP for histone marks in mouse spermatocytes\",\n      \"pmids\": [\"39637191\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether MSCI role reflects 7SK/elongation control or a distinct mechanism unresolved\", \"Direct chromatin recruitment mechanism unknown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Resolved a mechanism for direct viral restraint, showing LARP7 phase separates upon HIV-1 infection to sequester Tat via IDR lysines.\",\n      \"evidence\": \"Live-cell imaging of condensates, lysine mutagenesis, and Tat-dependent transcription assays\",\n      \"pmids\": [\"40113991\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Trigger linking infection to phase separation not defined\", \"Relationship between condensate and canonical 7SK snRNP unclear\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defined the LARP7-SIRT1 interaction at domain resolution and a downstream NLRP3 deacetylation axis controlling inflammasome activation.\",\n      \"evidence\": \"Domain-mapping Co-IP, proximity ligation, acetyl-proteomics mapping NLRP3 sites, and neuron-specific KO mice after ischemic stroke\",\n      \"pmids\": [\"41351020\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural basis of allosteric SIRT1 enhancement not solved\", \"Whether this is independent of nuclear 7SK functions unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How LARP7 partitions among its distinct roles—7SK/P-TEFb control, U6 methylation, telomerase maturation, SIRT1 modulation, and phase separation—within a cell, and what determines which function dominates in a given context, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model integrating nuclear RNP roles with cytoplasmic SIRT-axis functions\", \"Regulatory switches between functions not identified\", \"Structural basis of SIRT1 enhancement and condensate assembly not determined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [0, 1, 2, 3, 5]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [8, 9]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [11, 17]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 1, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [12, 16]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [15, 16]},\n      {\"term_id\": \"GO:0000228\", \"supporting_discovery_ids\": [20]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 1, 2]},\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [8, 9, 14]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [9, 19]}\n    ],\n    \"complexes\": [\"7SK snRNP\", \"telomerase complex\"],\n    \"partners\": [\"MePCE\", \"P-TEFb\", \"SIRT1\", \"HEXIM1\", \"SIRT6\", \"MCTS1\", \"STING\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":8,"faith_pct":87.5}}