{"gene":"TAF5L","run_date":"2026-06-10T10:51:54","timeline":{"discoveries":[{"year":2019,"finding":"TAF5L and TAF6L are components/co-activators of GNAT-HAT (PCAF/SAGA) complexes in mouse ESCs and transcriptionally activate c-Myc and Oct4 and their corresponding MYC and CORE regulatory networks, primarily through H3K9ac deposition and c-MYC recruitment, thereby maintaining self-renewal.","method":"CRISPR-Cas9 loss-of-function screen, ChIP-seq (H3K9ac), RNA-seq, and molecular epistasis in mouse ESCs","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — genome-wide CRISPR screen plus multiple orthogonal molecular methods (ChIP-seq, RNA-seq, c-MYC recruitment assays) in a single rigorous study with clear mechanistic readouts","pmids":["31005419"],"is_preprint":false},{"year":2026,"finding":"TAF5L (together with TADA1 and TAF6L) is a non-enzymatic SAGA CORE module subunit required for KAT2A protein stability; loss of TAF5L disrupts SAGA complex integrity, releasing non-chromatin-bound KAT2A that is degraded by the proteasome (via E3 ligase UBR5 and deubiquitinase OTUD5), resulting in reduced H3K9 acetylation.","method":"Fluorescence-based KAT2A stability reporter, CRISPR knockouts, proteomic profiling, focused CRISPR screen of ubiquitin-proteasome system genes","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods including fluorescence reporter, proteomics, and focused CRISPR screen, all converging on the same mechanistic conclusion in a single rigorous study","pmids":["42009663"],"is_preprint":false},{"year":2026,"finding":"High-resolution cryo-EM structure of endogenous human SAGA reveals that TAF5L and TAF6L contain major structural differences from their canonical TFIID paralogs (TAF5 and TAF6); TAF6L HEAT repeat domain provides a docking surface for the metazoan-specific splicing-factor module (SPL), and these structural rearrangements in TAF5L/TAF6L are directly required to accommodate SPL within the SAGA complex.","method":"Cryo-EM structure of affinity-ligand-purified endogenous human SAGA complex","journal":"Science advances","confidence":"High","confidence_rationale":"Tier 1 / Moderate — high-resolution structural determination of endogenous complex with functional domain identification, single study but rigorous structural method","pmids":["41849588"],"is_preprint":false},{"year":2025,"finding":"Loss of Taf5l in hematopoietic stem and progenitor cells strongly inhibits hematopoiesis in vivo, causing a buildup of immature hematopoietic cells in the bone marrow, associated with upregulation of interferon pathway genes, reduced mitochondrial activity, and increased megakaryocyte progenitor commitment; loss also enhances cell outgrowth and interferon pathway in a human MDS model.","method":"Genome-wide in vivo CRISPR knockout screen in HSPCs, bone marrow analysis, transcriptomic profiling","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo CRISPR screen validated by direct phenotypic and transcriptomic characterization, replicated across preprint and peer-reviewed publication","pmids":["41577693","40475452"],"is_preprint":false},{"year":2006,"finding":"TAF5L is preferentially expressed in testis and ovary during gametogenesis and embryogenesis in frogs; in vitro protein-DNA interaction assays demonstrated that TAF5L can participate in core promoter complexes as part of variant TAF-containing assemblies, consistent with a role in germ cell-specific transcription initiation.","method":"RT-PCR, in situ hybridization, in vitro protein-DNA interaction assays with recombinant proteins","journal":"Gene expression patterns : GEP","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — direct in vitro protein-DNA interaction assay but limited to frog TAF5L and single lab, functional consequence inferred rather than directly tested","pmids":["16412700"],"is_preprint":false},{"year":2019,"finding":"In the clam Meretrix petechialis, MpTAF5L interacts with the transcription factor MpMITF (via the N-terminal TAF5-NTD2 domain of MpTAF5L) and enhances MpMITF transcriptional activation activity; knockdown of MpTAF5L decreased expression of the MITF target gene MpBcl-2 without changing MpMITF mRNA levels, indicating coactivator function.","method":"Yeast two-hybrid assay, domain mapping, siRNA knockdown with target gene expression analysis","journal":"Fish & shellfish immunology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — yeast two-hybrid plus knockdown with target gene readout, but in a non-mammalian invertebrate model and single lab","pmids":["31743760"],"is_preprint":false},{"year":2026,"finding":"Lentiviral transduction of TAF5L in CD8+ Tregs boosted FOXP3 expression and was sufficient to enhance the suppressive function of these cells, identifying TAF5L as a molecular regulator of CD8+ Treg stability and function.","method":"Lentiviral transduction of TAF5L into primary human CD8+ Tregs, in vitro suppression assays, flow cytometry","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 3 / Weak — single lab, single overexpression approach with functional readout but limited mechanistic dissection of pathway","pmids":["41630158"],"is_preprint":false},{"year":2025,"finding":"High-resolution cryo-EM structure of endogenous human SAGA (preprint version) shows that TAF5L and TAF6L structural differences from canonical TFIID paralogs are directly implicated in structural rearrangements required to accommodate the SPL splicing-factor module; SPL binds SAGA through a smaller interface than in U2snRNP, sharing a deeply inserted helical motif.","method":"Cryo-EM structure of affinity-ligand-purified endogenous human SAGA","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — high-resolution structural method but preprint not yet peer-reviewed; largely superseded by the published version (PMID 41849588)","pmids":[],"is_preprint":true}],"current_model":"TAF5L is a non-enzymatic structural subunit of the SAGA (GNAT-HAT/PCAF) transcriptional coactivator complex, where it (together with TAF6L and TADA1) forms the CORE module required for complex integrity and KAT2A stability; within SAGA, TAF5L/TAF6L undergo metazoan-specific structural divergence from their TFIID paralogs to accommodate a splicing-factor module (SPL), and the complex drives gene expression through H3K9 acetylation deposition, c-MYC recruitment, and transcriptional activation of pluripotency (Oct4, c-Myc) and hematopoietic programs, with loss of TAF5L causing proteasomal degradation of KAT2A, impaired H3K9ac, blocked hematopoiesis, and loss of ESC self-renewal."},"narrative":{"mechanistic_narrative":"TAF5L is a non-enzymatic structural subunit of the SAGA (GNAT-HAT/PCAF) transcriptional coactivator complex that drives gene expression programs through histone H3K9 acetylation and transcription factor recruitment [PMID:31005419, PMID:42009663]. Together with TADA1 and TAF6L, TAF5L forms the SAGA CORE module that maintains complex integrity and stabilizes the acetyltransferase KAT2A; loss of TAF5L disrupts SAGA, releasing chromatin-unbound KAT2A for proteasomal degradation via the E3 ligase UBR5 and deubiquitinase OTUD5, with consequent loss of H3K9ac [PMID:42009663]. Cryo-EM of endogenous human SAGA shows that TAF5L and its partner TAF6L diverge structurally from their canonical TFIID paralogs (TAF5 and TAF6), and these rearrangements are required to accommodate the metazoan-specific splicing-factor (SPL) module within the complex [PMID:41849588]. Functionally, SAGA-associated TAF5L activity sustains self-renewal of mouse embryonic stem cells by transcriptionally activating c-Myc and Oct4 networks through H3K9ac deposition and c-MYC recruitment [PMID:31005419], and is required in vivo for hematopoiesis, where its loss arrests immature hematopoietic cells in the bone marrow and upregulates interferon pathway genes [PMID:41577693, PMID:40475452].","teleology":[{"year":2006,"claim":"Established that TAF5L can participate in core-promoter transcription complexes, providing the first evidence that it acts within variant TAF-containing assemblies rather than as a free factor.","evidence":"RT-PCR, in situ hybridization, and in vitro protein-DNA interaction assays in frog","pmids":["16412700"],"confidence":"Medium","gaps":["Functional consequence on transcription inferred, not directly tested","Limited to frog ortholog and germ-cell expression context","No identification of the mammalian complex it acts within"]},{"year":2019,"claim":"Defined TAF5L as a coactivator that enhances a sequence-specific transcription factor, showing it boosts target gene expression without altering the factor's own mRNA level.","evidence":"Yeast two-hybrid, domain mapping, and siRNA knockdown with target readout in the clam Meretrix petechialis","pmids":["31743760"],"confidence":"Medium","gaps":["Invertebrate model, single lab","Direct interaction shown by Y2H without orthogonal validation","Mechanism of transcriptional enhancement not resolved"]},{"year":2019,"claim":"Placed TAF5L within the GNAT-HAT/SAGA-PCAF coactivator complex and tied its function to a defined cellular program, resolving how it controls gene expression.","evidence":"Genome-wide CRISPR loss-of-function screen, H3K9ac ChIP-seq, RNA-seq, and molecular epistasis in mouse ESCs","pmids":["31005419"],"confidence":"High","gaps":["Does not define TAF5L's structural role within SAGA","Mechanism linking TAF5L to KAT2A activity not yet shown"]},{"year":2025,"claim":"Demonstrated a non-redundant in vivo requirement for TAF5L in hematopoiesis, distinguishing its physiological role from the ESC self-renewal context.","evidence":"Genome-wide in vivo CRISPR knockout screen in HSPCs with bone marrow and transcriptomic profiling, plus a human MDS model","pmids":["41577693","40475452"],"confidence":"High","gaps":["Causal link between SAGA disruption and the interferon/mitochondrial phenotypes not directly traced","Cell-intrinsic versus niche contributions not fully separated"]},{"year":2026,"claim":"Resolved the molecular basis of TAF5L's structural role: it is a CORE-module subunit whose integrity gates KAT2A protein stability via the ubiquitin-proteasome system.","evidence":"Fluorescence KAT2A stability reporter, CRISPR knockouts, proteomics, and a focused ubiquitin-proteasome CRISPR screen","pmids":["42009663"],"confidence":"High","gaps":["Direct physical contacts between TAF5L and KAT2A not mapped","Whether UBR5/OTUD5 act on KAT2A directly versus indirectly not fully resolved"]},{"year":2026,"claim":"Provided the structural explanation for why metazoan TAF5L/TAF6L diverge from TFIID paralogs, showing the rearrangements are needed to dock the splicing-factor module.","evidence":"Cryo-EM of affinity-purified endogenous human SAGA complex","pmids":["41849588"],"confidence":"High","gaps":["Functional consequence of SPL coupling for splicing or transcription not tested","TAF5L-specific contacts to SPL versus TAF6L-mediated docking not separated"]},{"year":2026,"claim":"Extended TAF5L function to adaptive immunity by showing it is sufficient to enhance suppressive CD8+ Treg identity, implicating it in immune-cell stability.","evidence":"Lentiviral TAF5L overexpression in primary human CD8+ Tregs with in vitro suppression assays and flow cytometry","pmids":["41630158"],"confidence":"Medium","gaps":["Single overexpression approach, no loss-of-function confirmation","Pathway linking TAF5L to FOXP3 not dissected","Dependence on SAGA/KAT2A in this context untested"]},{"year":null,"claim":"How TAF5L-dependent SAGA activity is selectively deployed across distinct cell types (ESC self-renewal, hematopoiesis, Treg function) and whether the SPL coupling links SAGA-driven transcription to splicing remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No mechanism for cell-type-specific gene selection by TAF5L/SAGA","Functional role of the SPL module not established","Direct TAF5L-KAT2A interaction interface unmapped"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0,5]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[1,2]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,1]}],"pathway":[{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0]},{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[0,1]}],"complexes":["SAGA (GNAT-HAT/PCAF) coactivator complex","SAGA CORE module"],"partners":["TAF6L","TADA1","KAT2A"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O75529","full_name":"TAF5-like RNA polymerase II p300/CBP-associated factor-associated factor 65 kDa subunit 5L","aliases":["PCAF-associated factor 65 beta","PAF65-beta"],"length_aa":589,"mass_kda":66.2,"function":"Functions as a component of the PCAF complex. The PCAF complex is capable of efficiently acetylating histones in a nucleosomal context. The PCAF complex could be considered as the human version of the yeast SAGA complex (Probable). With TAF6L, acts as an epigenetic regulator essential for somatic reprogramming. Regulates target genes through H3K9ac deposition and MYC recruitment which trigger MYC regulatory network to orchestrate gene expression programs to control embryonic stem cell state (By similarity)","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/O75529/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/TAF5L","classification":"Not Classified","n_dependent_lines":372,"n_total_lines":1208,"dependency_fraction":0.3079470198675497},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"TAF12","stoichiometry":10.0},{"gene":"TRRAP","stoichiometry":10.0},{"gene":"USP22","stoichiometry":4.0},{"gene":"CLASP2","stoichiometry":0.2},{"gene":"ENY2","stoichiometry":0.2},{"gene":"SF3B3","stoichiometry":0.2},{"gene":"SF3B5","stoichiometry":0.2},{"gene":"TBP","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/TAF5L","total_profiled":1310},"omim":[{"mim_id":"619015","title":"ENY2 TRANSCRIPTION AND EXPORT COMPLEX 2 SUBUNIT; ENY2","url":"https://www.omim.org/entry/619015"},{"mim_id":"619010","title":"ATXN7-LIKE 3; ATXN7L3","url":"https://www.omim.org/entry/619010"},{"mim_id":"612116","title":"UBIQUITIN-SPECIFIC PROTEASE 22; USP22","url":"https://www.omim.org/entry/612116"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nuclear speckles","reliability":"Supported"},{"location":"Cytoplasmic bodies","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/TAF5L"},"hgnc":{"alias_symbol":["PAF65B"],"prev_symbol":[]},"alphafold":{"accession":"O75529","domains":[{"cath_id":"1.25.40.500","chopping":"66-199","consensus_level":"high","plddt":85.1681,"start":66,"end":199},{"cath_id":"2.130.10.10","chopping":"257-304_332-582","consensus_level":"medium","plddt":86.0573,"start":257,"end":582}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O75529","model_url":"https://alphafold.ebi.ac.uk/files/AF-O75529-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O75529-F1-predicted_aligned_error_v6.png","plddt_mean":76.19},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TAF5L","jax_strain_url":"https://www.jax.org/strain/search?query=TAF5L"},"sequence":{"accession":"O75529","fasta_url":"https://rest.uniprot.org/uniprotkb/O75529.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O75529/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O75529"}},"corpus_meta":[{"pmid":"18045485","id":"PMC_18045485","title":"The candidate genes TAF5L, TCF7, PDCD1, IL6 and ICAM1 cannot be excluded from having effects in type 1 diabetes.","date":"2007","source":"BMC medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/18045485","citation_count":38,"is_preprint":false},{"pmid":"31005419","id":"PMC_31005419","title":"TAF5L and TAF6L Maintain Self-Renewal of Embryonic Stem Cells via the MYC Regulatory Network.","date":"2019","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/31005419","citation_count":37,"is_preprint":false},{"pmid":"16412700","id":"PMC_16412700","title":"Developmental and cell type-specific regulation of core promoter transcription factors in germ cells of frogs and mice.","date":"2006","source":"Gene expression patterns : GEP","url":"https://pubmed.ncbi.nlm.nih.gov/16412700","citation_count":37,"is_preprint":false},{"pmid":"23755131","id":"PMC_23755131","title":"Complex multi-block analysis identifies new immunologic and genetic disease progression patterns associated with the residual β-cell function 1 year after diagnosis of type 1 diabetes.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23755131","citation_count":19,"is_preprint":false},{"pmid":"31743760","id":"PMC_31743760","title":"TAF5L functions as transcriptional coactivator of MITF involved in the immune response of the clam Meretrix petechialis.","date":"2019","source":"Fish & shellfish immunology","url":"https://pubmed.ncbi.nlm.nih.gov/31743760","citation_count":8,"is_preprint":false},{"pmid":"33991433","id":"PMC_33991433","title":"Long non-coding RNAs and their targets as potential biomarkers in breast cancer.","date":"2021","source":"IET systems biology","url":"https://pubmed.ncbi.nlm.nih.gov/33991433","citation_count":7,"is_preprint":false},{"pmid":"16206511","id":"PMC_16206511","title":"The TAF5L gene on chromosome 1q42 is associated with type 1 diabetes in Russian affected patients.","date":"2005","source":"Autoimmunity","url":"https://pubmed.ncbi.nlm.nih.gov/16206511","citation_count":6,"is_preprint":false},{"pmid":"40475452","id":"PMC_40475452","title":"In vivo CRISPR screening identifies SAGA complex members as key regulators of hematopoiesis.","date":"2025","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/40475452","citation_count":4,"is_preprint":false},{"pmid":"40460829","id":"PMC_40460829","title":"Medications for opioid use disorder shape immune responses during chronic HIV infection.","date":"2025","source":"Cell reports. Medicine","url":"https://pubmed.ncbi.nlm.nih.gov/40460829","citation_count":1,"is_preprint":false},{"pmid":"41630158","id":"PMC_41630158","title":"Stabilization of Human CD8+ Treg in Inflammatory Environments Through FOXP3 Expression.","date":"2026","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/41630158","citation_count":1,"is_preprint":false},{"pmid":"42009663","id":"PMC_42009663","title":"Disruption of the SAGA CORE triggers collateral degradation of KAT2A.","date":"2026","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/42009663","citation_count":1,"is_preprint":false},{"pmid":"31191205","id":"PMC_31191205","title":"1q42.12q42.2 Deletion in a Child with Midline Defects and Hypoplasia of the Corpus Callosum.","date":"2019","source":"Molecular syndromology","url":"https://pubmed.ncbi.nlm.nih.gov/31191205","citation_count":1,"is_preprint":false},{"pmid":"41577693","id":"PMC_41577693","title":"In vivo CRISPR screening identifies SAGA complex members as key regulators of hematopoiesis.","date":"2026","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/41577693","citation_count":0,"is_preprint":false},{"pmid":"41849588","id":"PMC_41849588","title":"Insights into the structure and evolution of the human SAGA complex by affinity-ligand purification.","date":"2026","source":"Science advances","url":"https://pubmed.ncbi.nlm.nih.gov/41849588","citation_count":0,"is_preprint":false},{"pmid":"41696008","id":"PMC_41696008","title":"Genome-wide association study of nutrient composition in meat from three two-way crossbred pig populations using whole-genome resequencing.","date":"2026","source":"Frontiers in veterinary science","url":"https://pubmed.ncbi.nlm.nih.gov/41696008","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.07.31.667873","title":"Novel insights into the structure and evolution of the human SAGA complex by affinity-ligand purification","date":"2025-08-02","source":"bioRxiv","url":"https://doi.org/10.1101/2025.07.31.667873","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9639,"output_tokens":2159,"usd":0.030651,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9138,"output_tokens":2750,"usd":0.05722,"stage2_stop_reason":"end_turn"},"total_usd":0.087871,"stage1_batch_id":"msgbatch_017qqVz33Ga63SCDwzb35XPb","stage2_batch_id":"msgbatch_01Scr2Ei9x4HJMiRGxwrmvLK","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2019,\n      \"finding\": \"TAF5L and TAF6L are components/co-activators of GNAT-HAT (PCAF/SAGA) complexes in mouse ESCs and transcriptionally activate c-Myc and Oct4 and their corresponding MYC and CORE regulatory networks, primarily through H3K9ac deposition and c-MYC recruitment, thereby maintaining self-renewal.\",\n      \"method\": \"CRISPR-Cas9 loss-of-function screen, ChIP-seq (H3K9ac), RNA-seq, and molecular epistasis in mouse ESCs\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genome-wide CRISPR screen plus multiple orthogonal molecular methods (ChIP-seq, RNA-seq, c-MYC recruitment assays) in a single rigorous study with clear mechanistic readouts\",\n      \"pmids\": [\"31005419\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"TAF5L (together with TADA1 and TAF6L) is a non-enzymatic SAGA CORE module subunit required for KAT2A protein stability; loss of TAF5L disrupts SAGA complex integrity, releasing non-chromatin-bound KAT2A that is degraded by the proteasome (via E3 ligase UBR5 and deubiquitinase OTUD5), resulting in reduced H3K9 acetylation.\",\n      \"method\": \"Fluorescence-based KAT2A stability reporter, CRISPR knockouts, proteomic profiling, focused CRISPR screen of ubiquitin-proteasome system genes\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods including fluorescence reporter, proteomics, and focused CRISPR screen, all converging on the same mechanistic conclusion in a single rigorous study\",\n      \"pmids\": [\"42009663\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"High-resolution cryo-EM structure of endogenous human SAGA reveals that TAF5L and TAF6L contain major structural differences from their canonical TFIID paralogs (TAF5 and TAF6); TAF6L HEAT repeat domain provides a docking surface for the metazoan-specific splicing-factor module (SPL), and these structural rearrangements in TAF5L/TAF6L are directly required to accommodate SPL within the SAGA complex.\",\n      \"method\": \"Cryo-EM structure of affinity-ligand-purified endogenous human SAGA complex\",\n      \"journal\": \"Science advances\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — high-resolution structural determination of endogenous complex with functional domain identification, single study but rigorous structural method\",\n      \"pmids\": [\"41849588\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Loss of Taf5l in hematopoietic stem and progenitor cells strongly inhibits hematopoiesis in vivo, causing a buildup of immature hematopoietic cells in the bone marrow, associated with upregulation of interferon pathway genes, reduced mitochondrial activity, and increased megakaryocyte progenitor commitment; loss also enhances cell outgrowth and interferon pathway in a human MDS model.\",\n      \"method\": \"Genome-wide in vivo CRISPR knockout screen in HSPCs, bone marrow analysis, transcriptomic profiling\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo CRISPR screen validated by direct phenotypic and transcriptomic characterization, replicated across preprint and peer-reviewed publication\",\n      \"pmids\": [\"41577693\", \"40475452\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"TAF5L is preferentially expressed in testis and ovary during gametogenesis and embryogenesis in frogs; in vitro protein-DNA interaction assays demonstrated that TAF5L can participate in core promoter complexes as part of variant TAF-containing assemblies, consistent with a role in germ cell-specific transcription initiation.\",\n      \"method\": \"RT-PCR, in situ hybridization, in vitro protein-DNA interaction assays with recombinant proteins\",\n      \"journal\": \"Gene expression patterns : GEP\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — direct in vitro protein-DNA interaction assay but limited to frog TAF5L and single lab, functional consequence inferred rather than directly tested\",\n      \"pmids\": [\"16412700\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"In the clam Meretrix petechialis, MpTAF5L interacts with the transcription factor MpMITF (via the N-terminal TAF5-NTD2 domain of MpTAF5L) and enhances MpMITF transcriptional activation activity; knockdown of MpTAF5L decreased expression of the MITF target gene MpBcl-2 without changing MpMITF mRNA levels, indicating coactivator function.\",\n      \"method\": \"Yeast two-hybrid assay, domain mapping, siRNA knockdown with target gene expression analysis\",\n      \"journal\": \"Fish & shellfish immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — yeast two-hybrid plus knockdown with target gene readout, but in a non-mammalian invertebrate model and single lab\",\n      \"pmids\": [\"31743760\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Lentiviral transduction of TAF5L in CD8+ Tregs boosted FOXP3 expression and was sufficient to enhance the suppressive function of these cells, identifying TAF5L as a molecular regulator of CD8+ Treg stability and function.\",\n      \"method\": \"Lentiviral transduction of TAF5L into primary human CD8+ Tregs, in vitro suppression assays, flow cytometry\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, single overexpression approach with functional readout but limited mechanistic dissection of pathway\",\n      \"pmids\": [\"41630158\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"High-resolution cryo-EM structure of endogenous human SAGA (preprint version) shows that TAF5L and TAF6L structural differences from canonical TFIID paralogs are directly implicated in structural rearrangements required to accommodate the SPL splicing-factor module; SPL binds SAGA through a smaller interface than in U2snRNP, sharing a deeply inserted helical motif.\",\n      \"method\": \"Cryo-EM structure of affinity-ligand-purified endogenous human SAGA\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — high-resolution structural method but preprint not yet peer-reviewed; largely superseded by the published version (PMID 41849588)\",\n      \"pmids\": [],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"TAF5L is a non-enzymatic structural subunit of the SAGA (GNAT-HAT/PCAF) transcriptional coactivator complex, where it (together with TAF6L and TADA1) forms the CORE module required for complex integrity and KAT2A stability; within SAGA, TAF5L/TAF6L undergo metazoan-specific structural divergence from their TFIID paralogs to accommodate a splicing-factor module (SPL), and the complex drives gene expression through H3K9 acetylation deposition, c-MYC recruitment, and transcriptional activation of pluripotency (Oct4, c-Myc) and hematopoietic programs, with loss of TAF5L causing proteasomal degradation of KAT2A, impaired H3K9ac, blocked hematopoiesis, and loss of ESC self-renewal.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TAF5L is a non-enzymatic structural subunit of the SAGA (GNAT-HAT/PCAF) transcriptional coactivator complex that drives gene expression programs through histone H3K9 acetylation and transcription factor recruitment [#0, #1]. Together with TADA1 and TAF6L, TAF5L forms the SAGA CORE module that maintains complex integrity and stabilizes the acetyltransferase KAT2A; loss of TAF5L disrupts SAGA, releasing chromatin-unbound KAT2A for proteasomal degradation via the E3 ligase UBR5 and deubiquitinase OTUD5, with consequent loss of H3K9ac [#1]. Cryo-EM of endogenous human SAGA shows that TAF5L and its partner TAF6L diverge structurally from their canonical TFIID paralogs (TAF5 and TAF6), and these rearrangements are required to accommodate the metazoan-specific splicing-factor (SPL) module within the complex [#2]. Functionally, SAGA-associated TAF5L activity sustains self-renewal of mouse embryonic stem cells by transcriptionally activating c-Myc and Oct4 networks through H3K9ac deposition and c-MYC recruitment [#0], and is required in vivo for hematopoiesis, where its loss arrests immature hematopoietic cells in the bone marrow and upregulates interferon pathway genes [#3].\",\n  \"teleology\": [\n    {\n      \"year\": 2006,\n      \"claim\": \"Established that TAF5L can participate in core-promoter transcription complexes, providing the first evidence that it acts within variant TAF-containing assemblies rather than as a free factor.\",\n      \"evidence\": \"RT-PCR, in situ hybridization, and in vitro protein-DNA interaction assays in frog\",\n      \"pmids\": [\"16412700\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Functional consequence on transcription inferred, not directly tested\", \"Limited to frog ortholog and germ-cell expression context\", \"No identification of the mammalian complex it acts within\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Defined TAF5L as a coactivator that enhances a sequence-specific transcription factor, showing it boosts target gene expression without altering the factor's own mRNA level.\",\n      \"evidence\": \"Yeast two-hybrid, domain mapping, and siRNA knockdown with target readout in the clam Meretrix petechialis\",\n      \"pmids\": [\"31743760\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Invertebrate model, single lab\", \"Direct interaction shown by Y2H without orthogonal validation\", \"Mechanism of transcriptional enhancement not resolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Placed TAF5L within the GNAT-HAT/SAGA-PCAF coactivator complex and tied its function to a defined cellular program, resolving how it controls gene expression.\",\n      \"evidence\": \"Genome-wide CRISPR loss-of-function screen, H3K9ac ChIP-seq, RNA-seq, and molecular epistasis in mouse ESCs\",\n      \"pmids\": [\"31005419\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Does not define TAF5L's structural role within SAGA\", \"Mechanism linking TAF5L to KAT2A activity not yet shown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Demonstrated a non-redundant in vivo requirement for TAF5L in hematopoiesis, distinguishing its physiological role from the ESC self-renewal context.\",\n      \"evidence\": \"Genome-wide in vivo CRISPR knockout screen in HSPCs with bone marrow and transcriptomic profiling, plus a human MDS model\",\n      \"pmids\": [\"41577693\", \"40475452\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Causal link between SAGA disruption and the interferon/mitochondrial phenotypes not directly traced\", \"Cell-intrinsic versus niche contributions not fully separated\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Resolved the molecular basis of TAF5L's structural role: it is a CORE-module subunit whose integrity gates KAT2A protein stability via the ubiquitin-proteasome system.\",\n      \"evidence\": \"Fluorescence KAT2A stability reporter, CRISPR knockouts, proteomics, and a focused ubiquitin-proteasome CRISPR screen\",\n      \"pmids\": [\"42009663\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Direct physical contacts between TAF5L and KAT2A not mapped\", \"Whether UBR5/OTUD5 act on KAT2A directly versus indirectly not fully resolved\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Provided the structural explanation for why metazoan TAF5L/TAF6L diverge from TFIID paralogs, showing the rearrangements are needed to dock the splicing-factor module.\",\n      \"evidence\": \"Cryo-EM of affinity-purified endogenous human SAGA complex\",\n      \"pmids\": [\"41849588\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Functional consequence of SPL coupling for splicing or transcription not tested\", \"TAF5L-specific contacts to SPL versus TAF6L-mediated docking not separated\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Extended TAF5L function to adaptive immunity by showing it is sufficient to enhance suppressive CD8+ Treg identity, implicating it in immune-cell stability.\",\n      \"evidence\": \"Lentiviral TAF5L overexpression in primary human CD8+ Tregs with in vitro suppression assays and flow cytometry\",\n      \"pmids\": [\"41630158\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Single overexpression approach, no loss-of-function confirmation\", \"Pathway linking TAF5L to FOXP3 not dissected\", \"Dependence on SAGA/KAT2A in this context untested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How TAF5L-dependent SAGA activity is selectively deployed across distinct cell types (ESC self-renewal, hematopoiesis, Treg function) and whether the SPL coupling links SAGA-driven transcription to splicing remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"No mechanism for cell-type-specific gene selection by TAF5L/SAGA\", \"Functional role of the SPL module not established\", \"Direct TAF5L-KAT2A interaction interface unmapped\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 5]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [1, 2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"complexes\": [\"SAGA (GNAT-HAT/PCAF) coactivator complex\", \"SAGA CORE module\"],\n    \"partners\": [\"TAF6L\", \"TADA1\", \"KAT2A\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":4,"faith_total":4,"faith_pct":100.0}}