{"gene":"ASF1B","run_date":"2026-06-09T22:02:44","timeline":{"discoveries":[{"year":2010,"finding":"ASF1B expression is proliferation-dependent: both mRNA and protein decrease upon cell cycle exit in cultured cells. Depletion of ASF1B severely compromises proliferation and leads to aberrant nuclear structures, indicating a specific requirement for ASF1B (not ASF1a) in cell proliferation.","method":"siRNA depletion, cell cycle exit experiments, Western blot, immunofluorescence, transcriptional profiling","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KD with defined cellular phenotype, replicated across multiple cell systems, multiple orthogonal methods in a focused study","pmids":["21179005"],"is_preprint":false},{"year":2010,"finding":"HCF-1 directly and simultaneously interacts with both HSV DNA replication proteins and ASF1B. ASF1B co-localizes with HCF-1 at viral replication foci late in HSV infection, and depletion of ASF1B results in significantly reduced viral DNA accumulation, indicating ASF1B functions in viral DNA replication via chromatin reorganization downstream of HCF-1 recruitment.","method":"Co-immunoprecipitation, co-localization (immunofluorescence), siRNA depletion with viral DNA quantification","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP showing direct interaction, co-localization, and functional KD with specific phenotypic readout (viral DNA accumulation), multiple orthogonal methods in single study","pmids":["20133788"],"is_preprint":false},{"year":2013,"finding":"ASF1a and ASF1b, which arose by gene duplication at the ancestor of jawed vertebrates, have distinct preferential interactions with different H3-H4 chaperones; regions outside the primary interaction surface (in the N- and C-terminal regions) are key determinants of these preferential interactions, as demonstrated by biochemical and structural analyses.","method":"Biochemical binding assays, structural analysis, evolutionary/comparative genomics, positive selection analysis","journal":"Molecular biology and evolution","confidence":"Medium","confidence_rationale":"Tier 1-2 / Moderate — structural and biochemical approaches combined, but abstracts do not fully detail reconstitution or mutagenesis specifics for ASF1B specifically","pmids":["23645555"],"is_preprint":false},{"year":2016,"finding":"ASF1B promotes human β-cell proliferation in a histone-binding-dependent manner; the histone-binding-deficient mutant V94R fails to induce proliferation. Co-expression of histone H3.3 (but not H3.1 or H3.2) synergistically augments ASF1B-mediated β-cell proliferation, and suppression of endogenous H3.3 attenuates the stimulatory effect of ASF1B, establishing that ASF1B requires histone H3.3 binding for its proliferative function.","method":"Overexpression, dominant-negative (V94R) mutant, siRNA knockdown of H3.3, multiple proliferation assays (BrdU, Ki67, mitotic markers)","journal":"Cell cycle (Georgetown, Tex.)","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — active-site/binding-domain mutagenesis (V94R) combined with co-expression and KD experiments with multiple orthogonal readouts in a single study","pmids":["27753532"],"is_preprint":false},{"year":2016,"finding":"Loss of ASF1B in mice reduces female reproductive capacity; ASF1B is specifically expressed in germ cells with peak expression correlating with meiosis, and Asf1b-null female mice show altered timing of meiotic entry and defective gonad development, indicating ASF1B plays a role in chromatin modifications at meiotic entry.","method":"Asf1b gene-trap knockout mouse, β-galactosidase reporter assay, histological analysis, reproductive phenotyping","journal":"Reproduction (Cambridge, England)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO model with defined reproductive/meiotic phenotype, but molecular mechanism downstream of ASF1B loss not fully resolved at molecular level from abstract","pmids":["26850882"],"is_preprint":false},{"year":2020,"finding":"ASF1B forms stable complexes with CDK9 and positively regulates CDK9 stabilization in cervical cancer cells; ASF1B knockdown reduces CDK9 protein levels.","method":"Co-immunoprecipitation, Western blot, siRNA knockdown, in vivo tumor xenograft model","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — Co-IP demonstrating complex formation and KD showing reduced CDK9 stability, replicated in vivo, but stabilization mechanism not biochemically dissected","pmids":["32848135"],"is_preprint":false},{"year":2021,"finding":"Asf1a, but not Asf1b, is required for histone H3.3 assembly in the paternal pronucleus after fertilization. Knockdown of Asf1b (but not Asf1a) nearly eliminates nuclear accumulation of PCNA in morula-stage embryos, indicating ASF1B specifically safeguards pre-implantation embryo development by regulating cell proliferation, while Asf1a regulates H3K56ac levels and Oct4 expression.","method":"Morpholino-mediated knockdown, immunofluorescence with specific antibodies, confocal microscopy in mouse embryos","journal":"Epigenetics & chromatin","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — specific Morpholino KD with defined molecular readouts (PCNA, H3.3, H3K56ac), orthogonal to genetic KO data, single lab","pmids":["34906203"],"is_preprint":false},{"year":2022,"finding":"ASF1B knockdown in HCC cells reduces expression of PCNA, cyclinB1, cyclinE2, and CDK9, and ASF1B interacts with CDK9 in HCC cells, consistent with a role for ASF1B-CDK9 complex in cell cycle regulation.","method":"Co-immunoprecipitation, Western blot, siRNA knockdown","journal":"Frontiers in oncology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP and KD experiment in a single lab, replicates CDK9 interaction finding from PMID:32848135 but with no additional mechanistic depth","pmids":["35087760"],"is_preprint":false},{"year":2022,"finding":"ASF1B knockdown increases S-phase cell cycle arrest and activates checkpoint kinases Chk1 and Chk2, indicating ASF1B normally suppresses replication checkpoint activation in pancreatic cancer cells.","method":"siRNA knockdown, flow cytometry cell cycle analysis, Western blot for Chk1/Chk2 phosphorylation","journal":"Cancer biomarkers : section A of Disease markers","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, KD with pathway readout but no direct epistasis or reconstitution","pmids":["35599471"],"is_preprint":false},{"year":2023,"finding":"ASF1B interacts with and occupies the TLK1 gene locus (ChIP assay), and the interaction between ASF1B and TLK1 promotes proliferation, cell cycle progression, and metastasis of low-grade glioma cells; overexpression of TLK1 rescues the effects of ASF1B interference.","method":"ChIP assay, co-expression rescue experiments, siRNA knockdown, cell functional assays","journal":"Annals of medicine","confidence":"Low","confidence_rationale":"Tier 3 / Weak — ChIP and rescue experiments, but the molecular nature of ASF1B-TLK1 interaction not biochemically characterized at protein level","pmids":["36947060"],"is_preprint":false},{"year":2024,"finding":"Transcription factor FOXM1 directly binds the ASF1B promoter region and regulates ASF1B transcription. In turn, ASF1B regulates PRDX3 transcription in a FOXM1-dependent manner, forming a FOXM1-ASF1B-PRDX3 axis that controls GC cell proliferation and oxidative stress balance.","method":"ChIP assay, FOXM1 inhibitor (thiostrepton) treatment, knockdown/overexpression experiments, in vitro and in vivo tumor models","journal":"Cancer letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct promoter binding demonstrated by ChIP, functional axis validated with inhibitor and KD/OE, two orthogonal methods in single study","pmids":["38537775"],"is_preprint":false},{"year":2024,"finding":"CDAN1 dimerizes and assembles into cytosolic complexes with CDIN1 and multiple copies of ASF1A/B. Cryo-EM structures reveal that CDAN1 engages ASF1B via two B-domains (found in other ASF1-binding partners) and two helices that mimic histone H3 binding. CDAN1 can recruit two ASF1 molecules simultaneously and sequesters/inhibits ASF1 chaperone function; ASF1A and ASF1B have different requirements for CDAN1 engagement.","method":"Single-particle cryo-EM, biochemical reconstitution, structural analysis","journal":"bioRxiv (preprint)","confidence":"High","confidence_rationale":"Tier 1 / Moderate — cryo-EM structure with biochemical reconstitution; direct structural and mechanistic characterization of the inhibitory complex, preprint not yet peer-reviewed but orthogonal methods within single rigorous study","pmids":["bio_10.1101_2024.08.08.607204"],"is_preprint":true},{"year":2025,"finding":"ASF1B promotes gastric cancer progression by downregulating histone H2AC20, which activates the PI3K/AKT and ERK1/2 signaling pathways; identified by IP-MS and TMT proteomics to define the ASF1B-interacting protein network.","method":"Immunoprecipitation-Mass Spectrometry (IP-MS), TMT proteomics, ASF1B knockout/overexpression, in vitro and in vivo tumor models, organoids","journal":"Frontiers in pharmacology","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — IP-MS identifies interaction partners, functional pathway validated with KO/OE models and in vivo, but direct H2AC20 regulation mechanism not fully mechanistically dissected from abstract","pmids":["40041497"],"is_preprint":false},{"year":2026,"finding":"ASF1B recruits the transcription factor HOXB3, promoting ZDHHC9 transcription. ZDHHC9 then palmitoylates PCBP1 at residue C109, inhibiting PCBP1 ubiquitination and suppressing SLC7A11-mediated ferroptosis, thus promoting gastric cancer liver metastasis. Identified by immunoprecipitation and LC-MS analyses.","method":"Immunoprecipitation/LC-MS, transcriptome sequencing, label-free proteomics, spleen-injection liver metastasis model, IHC, immunofluorescence","journal":"NPJ precision oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP/LC-MS for interaction, mechanistic pathway validated by rescue assays, but multiple steps between ASF1B and ferroptosis mean ASF1B-specific mechanistic attribution is indirect","pmids":["41535416"],"is_preprint":false},{"year":2026,"finding":"ASF1B occupies >70% of H3.3 nucleosomes in mouse fetal liver erythroid cells and determines H3.3 enrichment at erythroid gene promoters and enhancers. ASF1B predominantly regulates H3.3-encoding genes and erythroid genes (with ASF1A serving a compensatory function). Loss of ASF1B de-represses embryonic/fetal globin genes by altering H3.3 enrichment, erythroid transcription factor binding, and chromatin accessibility. The regulatory pathway involves recruitment of chromatin remodeler BRG1 and accumulation of H3K27ac at active chromatin.","method":"ChIP-seq, ATAC-seq, ASF1B knockout in mouse fetal liver cells, transcriptome sequencing, co-immunoprecipitation for BRG1 interaction","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — genome-wide ChIP-seq directly maps ASF1B to H3.3 nucleosomes, KO shows functional consequences at chromatin and transcriptional level, BRG1 recruitment validated; multiple orthogonal methods in single rigorous study","pmids":["42100853"],"is_preprint":false},{"year":2026,"finding":"ASF1B recruits the lactyltransferase p300, thereby promoting histone H3K18 lactylation (H3K18la) in hepatocellular carcinoma cells, forming a positive feedback loop with H3K18la.","method":"Co-immunoprecipitation, ChIP sequencing, Cut&Run, dual-luciferase reporter assay","journal":"Cells","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — Co-IP demonstrates ASF1B-p300 interaction and ChIP shows H3K18la changes, but mechanistic detail of how ASF1B recruits p300 is not fully characterized from abstract","pmids":["42193960"],"is_preprint":false}],"current_model":"ASF1B is a histone H3-H4 chaperone that functions primarily during DNA replication and cell proliferation: it occupies H3.3 nucleosomes genome-wide, recruits chromatin remodelers (BRG1) and histone modifiers (p300/H3K18la), is transcriptionally activated by FOXM1, is inhibited by CDAN1 via a structural mimicry mechanism (sequestering ASF1B in cytosolic complexes), interacts with CDK9 to promote its stabilization, is coupled to DNA replication machinery via HCF-1, and requires intact histone-binding capacity (V94R-sensitive) and H3.3 to drive cell proliferation; its loss activates replication checkpoints (Chk1/Chk2) and in vivo impairs meiosis and erythropoiesis."},"narrative":{"mechanistic_narrative":"ASF1B is a histone H3-H4 chaperone with a specific, non-redundant role in cell proliferation and chromatin assembly during DNA replication [PMID:21179005, PMID:27753532]. Its activity depends on intact histone-binding capacity—the V94R binding-deficient mutant fails to drive proliferation—and on histone H3.3 in particular, which synergizes with ASF1B and is required for its proliferative effect [PMID:27753532]. Genome-wide, ASF1B occupies the majority of H3.3 nucleosomes and determines H3.3 enrichment at promoters and enhancers, working with the chromatin remodeler BRG1 and H3K27ac to control lineage gene programs; its loss de-represses developmentally silenced genes [PMID:42100853]. ASF1B is functionally coupled to replication machinery via HCF-1, with which it co-localizes at replication foci, and its depletion impairs DNA replication [PMID:20133788]. Diverging from the paralog ASF1A, ASF1B carries distinct N- and C-terminal determinants that specify preferential chaperone interactions [PMID:23645555], and it is selectively required to sustain proliferation, such that loss triggers S-phase arrest and Chk1/Chk2 checkpoint activation [PMID:21179005, PMID:35599471]. ASF1B chaperone function is held in check by CDAN1, which assembles cytosolic complexes that sequester ASF1B through two B-domains and histone-H3-mimicking helices [PMID:bio_10.1101_2024.08.08.607204]. In proliferative and oncogenic contexts ASF1B is transcriptionally induced by FOXM1 and feeds forward to regulate downstream effectors such as PRDX3 [PMID:38537775], stabilizes CDK9 [PMID:32848135], and recruits chromatin modifiers including the lactyltransferase p300 to promote H3K18 lactylation [PMID:42193960]. In vivo, ASF1B is required for normal meiotic entry and gonad development and for pre-implantation embryo proliferation [PMID:26850882, PMID:34906203].","teleology":[{"year":2010,"claim":"Established that ASF1B, distinct from ASF1A, is specifically required for cell proliferation, defining its core biological role rather than treating the two paralogs as interchangeable.","evidence":"siRNA depletion, cell-cycle exit assays, and transcriptional profiling in cultured cells","pmids":["21179005"],"confidence":"High","gaps":["Molecular basis of the ASF1B-specific requirement not resolved","Did not define genome-wide chromatin targets"]},{"year":2010,"claim":"Linked ASF1B to active DNA replication by showing it acts downstream of HCF-1 at replication foci, connecting the chaperone to the replication machinery.","evidence":"Co-IP, immunofluorescence co-localization, and siRNA depletion with viral DNA quantification in HSV infection","pmids":["20133788"],"confidence":"High","gaps":["Demonstrated in a viral replication context; relevance to cellular replication inferred","Mechanism of chromatin reorganization downstream of HCF-1 not detailed"]},{"year":2013,"claim":"Explained why ASF1A and ASF1B are non-redundant by mapping divergent N- and C-terminal regions outside the core interface that specify distinct chaperone partnerships.","evidence":"Biochemical binding assays, structural analysis, and evolutionary/positive-selection analysis","pmids":["23645555"],"confidence":"Medium","gaps":["ASF1B-specific reconstitution and mutagenesis details limited","Functional consequences of preferential interactions not tested in cells"]},{"year":2016,"claim":"Defined the molecular requirement for ASF1B proliferative function as histone binding and specifically H3.3, not H3.1/H3.2.","evidence":"Overexpression, V94R binding-deficient mutant, H3.3 knockdown, and multiple proliferation readouts in human beta-cells","pmids":["27753532"],"confidence":"High","gaps":["Downstream chromatin events of ASF1B-H3.3 deposition not mapped","Restricted to beta-cell model"]},{"year":2016,"claim":"Demonstrated an in vivo developmental role, showing ASF1B is required for normal meiotic entry timing and gonad development.","evidence":"Asf1b gene-trap knockout mouse with beta-gal reporter, histology, and reproductive phenotyping","pmids":["26850882"],"confidence":"Medium","gaps":["Molecular mechanism downstream of ASF1B loss in germ cells not resolved","Chromatin targets in meiosis not identified"]},{"year":2021,"claim":"Separated ASF1A and ASF1B roles in early embryogenesis, attributing proliferation maintenance (PCNA accumulation) to ASF1B and paternal H3.3 assembly to ASF1A.","evidence":"Morpholino knockdown with immunofluorescence for PCNA, H3.3, and H3K56ac in mouse embryos","pmids":["34906203"],"confidence":"Medium","gaps":["Single-lab morpholino approach","Direct mechanism linking ASF1B to PCNA accumulation not defined"]},{"year":2020,"claim":"Identified CDK9 as an ASF1B partner that ASF1B stabilizes, extending ASF1B function into cell-cycle/transcriptional kinase regulation in cancer.","evidence":"Co-IP, Western blot, siRNA knockdown, and xenograft model in cervical cancer cells","pmids":["32848135","35087760"],"confidence":"Medium","gaps":["Biochemical mechanism of CDK9 stabilization not dissected","Whether stabilization requires histone-chaperone activity unknown"]},{"year":2022,"claim":"Placed ASF1B upstream of the replication checkpoint, showing its loss causes S-phase arrest and Chk1/Chk2 activation.","evidence":"siRNA knockdown, flow cytometry cell-cycle analysis, and Chk1/Chk2 phospho-Western in pancreatic cancer cells","pmids":["35599471"],"confidence":"Low","gaps":["No epistasis or reconstitution to establish directness","Single-lab observational link"]},{"year":2024,"claim":"Defined an upstream transcriptional driver, showing FOXM1 directly activates ASF1B which then regulates PRDX3, embedding ASF1B in a proliferation/oxidative-stress axis.","evidence":"ChIP, FOXM1 inhibitor (thiostrepton), knockdown/overexpression, and in vitro/in vivo gastric cancer models","pmids":["38537775"],"confidence":"Medium","gaps":["Mechanism by which ASF1B controls PRDX3 transcription unclear","Whether axis is gastric-cancer-specific not addressed"]},{"year":2024,"claim":"Provided a structural mechanism for ASF1B inhibition, showing CDAN1/CDIN1 sequester ASF1B via B-domains and histone-H3-mimicking helices.","evidence":"Single-particle cryo-EM and biochemical reconstitution of CDAN1-ASF1 complexes (preprint)","pmids":["bio_10.1101_2024.08.08.607204"],"confidence":"High","gaps":["Cellular consequences of CDAN1 sequestration on ASF1B function not quantified","Preprint, not peer-reviewed"]},{"year":2026,"claim":"Delivered the genome-wide chaperone model, mapping ASF1B to most H3.3 nucleosomes and showing it controls H3.3 enrichment, BRG1 recruitment, and lineage gene repression in erythropoiesis.","evidence":"ChIP-seq, ATAC-seq, transcriptome sequencing, BRG1 Co-IP, and ASF1B knockout in mouse fetal liver erythroid cells","pmids":["42100853"],"confidence":"High","gaps":["How ASF1B selects H3.3 sites genome-wide not defined","Extent of ASF1A compensation across loci incomplete"]},{"year":2026,"claim":"Extended ASF1B to chromatin-modifier recruitment, showing it brings p300 to chromatin to promote H3K18 lactylation in HCC.","evidence":"Co-IP, ChIP-seq, Cut&Run, and dual-luciferase reporter in hepatocellular carcinoma cells","pmids":["42193960"],"confidence":"Medium","gaps":["Mechanism of ASF1B-p300 recruitment not characterized","Direct vs indirect H3K18la control unresolved"]},{"year":null,"claim":"How ASF1B achieves H3.3-selective, locus-specific deposition and integrates its chaperone activity with its many reported cancer signaling partners remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model linking histone-chaperone function to CDK9/HOXB3/p300 effects","Determinants of ASF1B target-site specificity unknown","Whether oncogenic functions require intact histone binding largely untested"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0042393","term_label":"histone binding","supporting_discovery_ids":[3,14]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[1,14]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,14]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[11]}],"pathway":[{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[14,15]},{"term_id":"R-HSA-69306","term_label":"DNA Replication","supporting_discovery_ids":[1,8]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[0,8]}],"complexes":["CDAN1-CDIN1-ASF1 cytosolic complex"],"partners":["HCF-1","CDK9","CDAN1","CDIN1","BRG1","P300","HOXB3","TLK1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9NVP2","full_name":"Histone chaperone ASF1B","aliases":["Anti-silencing function protein 1 homolog B","hAsf1","hAsf1b","CCG1-interacting factor A-II","CIA-II","hCIA-II"],"length_aa":202,"mass_kda":22.4,"function":"Histone chaperone that facilitates histone deposition and histone exchange and removal during nucleosome assembly and disassembly (PubMed:11897662, PubMed:14718166, PubMed:15664198, PubMed:16151251, PubMed:21454524, PubMed:26527279). Cooperates with chromatin assembly factor 1 (CAF-1) to promote replication-dependent chromatin assembly (PubMed:11897662, PubMed:14718166, PubMed:15664198, PubMed:16151251). Also involved in the nuclear import of the histone H3-H4 dimer together with importin-4 (IPO4): specifically recognizes and binds newly synthesized histones with the monomethylation of H3 'Lys-9' (H3K9me1) and diacetylation at 'Lys-5' and 'Lys-12' of H4 (H4K5K12ac) marks in the cytosol (PubMed:20953179, PubMed:21454524, PubMed:26527279). Does not participate in replication-independent nucleosome deposition which is mediated by ASF1A and HIRA (PubMed:11897662, PubMed:14718166, PubMed:15664198, PubMed:16151251). Required for gonad development (PubMed:12842904)","subcellular_location":"Nucleus; Cytoplasm, cytosol","url":"https://www.uniprot.org/uniprotkb/Q9NVP2/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ASF1B","classification":"Not Classified","n_dependent_lines":153,"n_total_lines":1208,"dependency_fraction":0.12665562913907286},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/ASF1B","total_profiled":1310},"omim":[{"mim_id":"615614","title":"MMS22-LIKE PROTEIN; MMS22L","url":"https://www.omim.org/entry/615614"},{"mim_id":"609190","title":"ANTI-SILENCING FUNCTION 1B HISTONE CHAPERONE; ASF1B","url":"https://www.omim.org/entry/609190"},{"mim_id":"609189","title":"ANTI-SILENCING FUNCTION 1A HISTONE CHAPERONE; ASF1A","url":"https://www.omim.org/entry/609189"},{"mim_id":"604546","title":"TONSOKU-LIKE DNA REPAIR PROTEIN; TONSL","url":"https://www.omim.org/entry/604546"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Enhanced","locations":[{"location":"Nucleoplasm","reliability":"Enhanced"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"lymphoid tissue","ntpm":21.6},{"tissue":"testis","ntpm":36.2}],"url":"https://www.proteinatlas.org/search/ASF1B"},"hgnc":{"alias_symbol":["FLJ10604"],"prev_symbol":[]},"alphafold":{"accession":"Q9NVP2","domains":[{"cath_id":"2.60.40.1490","chopping":"3-147","consensus_level":"high","plddt":96.6993,"start":3,"end":147}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NVP2","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NVP2-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NVP2-F1-predicted_aligned_error_v6.png","plddt_mean":84.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ASF1B","jax_strain_url":"https://www.jax.org/strain/search?query=ASF1B"},"sequence":{"accession":"Q9NVP2","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9NVP2.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9NVP2/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NVP2"}},"corpus_meta":[{"pmid":"21179005","id":"PMC_21179005","title":"Asf1b, the necessary Asf1 isoform for proliferation, is predictive of outcome in breast cancer.","date":"2010","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/21179005","citation_count":139,"is_preprint":false},{"pmid":"20133788","id":"PMC_20133788","title":"Transcriptional coactivator HCF-1 couples the histone chaperone Asf1b to HSV-1 DNA replication components.","date":"2010","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/20133788","citation_count":57,"is_preprint":false},{"pmid":"32848135","id":"PMC_32848135","title":"ASF1B promotes cervical cancer progression through stabilization of CDK9.","date":"2020","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/32848135","citation_count":55,"is_preprint":false},{"pmid":"23645555","id":"PMC_23645555","title":"Subfunctionalization via adaptive evolution influenced by genomic context: the case of histone chaperones ASF1a and ASF1b.","date":"2013","source":"Molecular biology and evolution","url":"https://pubmed.ncbi.nlm.nih.gov/23645555","citation_count":55,"is_preprint":false},{"pmid":"27753532","id":"PMC_27753532","title":"Histone chaperone ASF1B promotes human β-cell proliferation via recruitment of histone H3.3.","date":"2016","source":"Cell cycle (Georgetown, Tex.)","url":"https://pubmed.ncbi.nlm.nih.gov/27753532","citation_count":39,"is_preprint":false},{"pmid":"35087760","id":"PMC_35087760","title":"ASF1B Serves as a Potential Therapeutic Target by Influencing Cell Cycle and Proliferation in Hepatocellular Carcinoma.","date":"2022","source":"Frontiers in oncology","url":"https://pubmed.ncbi.nlm.nih.gov/35087760","citation_count":28,"is_preprint":false},{"pmid":"26850882","id":"PMC_26850882","title":"Loss of the histone chaperone ASF1B reduces female reproductive capacity in mice.","date":"2016","source":"Reproduction (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/26850882","citation_count":28,"is_preprint":false},{"pmid":"34568067","id":"PMC_34568067","title":"ASF1B Promotes Oncogenesis in Lung Adenocarcinoma and Other Cancer Types.","date":"2021","source":"Frontiers in oncology","url":"https://pubmed.ncbi.nlm.nih.gov/34568067","citation_count":27,"is_preprint":false},{"pmid":"32764956","id":"PMC_32764956","title":"LINC00665 Promotes the Progression of Multiple Myeloma by Adsorbing miR-214-3p and Positively Regulating the Expression of PSMD10 and ASF1B.","date":"2020","source":"OncoTargets and therapy","url":"https://pubmed.ncbi.nlm.nih.gov/32764956","citation_count":16,"is_preprint":false},{"pmid":"38537775","id":"PMC_38537775","title":"Activation of the FOXM1/ASF1B/PRDX3 axis confers hyperproliferative and antioxidative stress reactivity to gastric cancer.","date":"2024","source":"Cancer letters","url":"https://pubmed.ncbi.nlm.nih.gov/38537775","citation_count":12,"is_preprint":false},{"pmid":"35103478","id":"PMC_35103478","title":"ASF1B enhances migration and invasion of lung cancers cell via regulating the P53-mediated epithelial-mesenchymal transformation (EMT) signaling pathway.","date":"2022","source":"Neoplasma","url":"https://pubmed.ncbi.nlm.nih.gov/35103478","citation_count":10,"is_preprint":false},{"pmid":"34906203","id":"PMC_34906203","title":"Distinct role of histone chaperone Asf1a and Asf1b during fertilization and pre-implantation embryonic development in mice.","date":"2021","source":"Epigenetics & chromatin","url":"https://pubmed.ncbi.nlm.nih.gov/34906203","citation_count":10,"is_preprint":false},{"pmid":"35599471","id":"PMC_35599471","title":"Downregulation of ASF1B inhibits tumor progression and enhances efficacy of cisplatin in pancreatic cancer.","date":"2022","source":"Cancer biomarkers : section A of Disease markers","url":"https://pubmed.ncbi.nlm.nih.gov/35599471","citation_count":10,"is_preprint":false},{"pmid":"36114946","id":"PMC_36114946","title":"miR-24-3p Regulates Epithelial-Mesenchymal Transition and the Malignant Phenotype of Pancreatic Adenocarcinoma by Regulating ASF1B Expression.","date":"2022","source":"Biochemical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/36114946","citation_count":6,"is_preprint":false},{"pmid":"37153049","id":"PMC_37153049","title":"Knockdown of ASF1B inhibits cell proliferation, migration, invasion and cisplatin resistance in gastric cancer through the Myc pathway.","date":"2023","source":"Oncology letters","url":"https://pubmed.ncbi.nlm.nih.gov/37153049","citation_count":6,"is_preprint":false},{"pmid":"36178207","id":"PMC_36178207","title":"The circCDK17/miR-122-5p/ASF1B axis regulates the progression of cervical cancer.","date":"2022","source":"Histology and histopathology","url":"https://pubmed.ncbi.nlm.nih.gov/36178207","citation_count":6,"is_preprint":false},{"pmid":"36007337","id":"PMC_36007337","title":"miR-767-3p suppresses melanoma progression by inhibiting ASF1B expression.","date":"2022","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/36007337","citation_count":5,"is_preprint":false},{"pmid":"36947060","id":"PMC_36947060","title":"The interaction between ASF1B and TLK1 promotes the malignant progression of low-grade glioma.","date":"2023","source":"Annals of medicine","url":"https://pubmed.ncbi.nlm.nih.gov/36947060","citation_count":4,"is_preprint":false},{"pmid":"38164276","id":"PMC_38164276","title":"Carcinogenic Role and Clinical Significance of Histone H3-H4 Chaperone Anti-silencing Function 1 B (ASF1B) in Lung Adenocarcinoma.","date":"2024","source":"Journal of Cancer","url":"https://pubmed.ncbi.nlm.nih.gov/38164276","citation_count":3,"is_preprint":false},{"pmid":"40041497","id":"PMC_40041497","title":"ASF1B promotes gastric cancer progression by modulating H2AC20 and activating PI3K/AKT and ERK1/2 pathways.","date":"2025","source":"Frontiers in pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/40041497","citation_count":2,"is_preprint":false},{"pmid":"41535416","id":"PMC_41535416","title":"ASF1B promotes gastric cancer liver metastasis through inhibiting ZDHHC9/PCBP1/ SLC7A11 signaling axis mediated ferroptosis.","date":"2026","source":"NPJ precision oncology","url":"https://pubmed.ncbi.nlm.nih.gov/41535416","citation_count":1,"is_preprint":false},{"pmid":"42100853","id":"PMC_42100853","title":"ASF1B promotes erythropoiesis by regulating the establishment and enrichment of H3.3 nucleosomes.","date":"2026","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/42100853","citation_count":0,"is_preprint":false},{"pmid":"41585149","id":"PMC_41585149","title":"APOBEC3B/ASF1B-TGF-β signaling axis promotes epithelial-mesenchymal transition in HPV-positive oropharyngeal cancer.","date":"2025","source":"Journal of dental sciences","url":"https://pubmed.ncbi.nlm.nih.gov/41585149","citation_count":0,"is_preprint":false},{"pmid":"42193960","id":"PMC_42193960","title":"A Feedback Loop Driven by H3K18la and ASF1B via the LINC02732-miR-1291 Axis Promotes Hepatocellular Carcinoma Proliferation.","date":"2026","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/42193960","citation_count":0,"is_preprint":false},{"pmid":"42114389","id":"PMC_42114389","title":"Ablation of ASF1B mitigates the proliferation of A549 cells and enhances anti-PD-L1 therapy by regulating ferroptosis.","date":"2026","source":"Tissue & cell","url":"https://pubmed.ncbi.nlm.nih.gov/42114389","citation_count":0,"is_preprint":false},{"pmid":"34103943","id":"PMC_34103943","title":"LINC00665 Promotes the Progression of Multiple Myeloma by Adsorbing miR-214-3p and Positively Regulating the Expression of PSMD10 and ASF1B [Retraction].","date":"2021","source":"OncoTargets and therapy","url":"https://pubmed.ncbi.nlm.nih.gov/34103943","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.08.08.607204","title":"Mechanism of ASF1 Inhibition by CDAN1","date":"2024-08-08","source":"bioRxiv","url":"https://doi.org/10.1101/2024.08.08.607204","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":15749,"output_tokens":4127,"usd":0.054576,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":12050,"output_tokens":3848,"usd":0.078225,"stage2_stop_reason":"end_turn"},"total_usd":0.132801,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2010,\n      \"finding\": \"ASF1B expression is proliferation-dependent: both mRNA and protein decrease upon cell cycle exit in cultured cells. Depletion of ASF1B severely compromises proliferation and leads to aberrant nuclear structures, indicating a specific requirement for ASF1B (not ASF1a) in cell proliferation.\",\n      \"method\": \"siRNA depletion, cell cycle exit experiments, Western blot, immunofluorescence, transcriptional profiling\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KD with defined cellular phenotype, replicated across multiple cell systems, multiple orthogonal methods in a focused study\",\n      \"pmids\": [\"21179005\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"HCF-1 directly and simultaneously interacts with both HSV DNA replication proteins and ASF1B. ASF1B co-localizes with HCF-1 at viral replication foci late in HSV infection, and depletion of ASF1B results in significantly reduced viral DNA accumulation, indicating ASF1B functions in viral DNA replication via chromatin reorganization downstream of HCF-1 recruitment.\",\n      \"method\": \"Co-immunoprecipitation, co-localization (immunofluorescence), siRNA depletion with viral DNA quantification\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP showing direct interaction, co-localization, and functional KD with specific phenotypic readout (viral DNA accumulation), multiple orthogonal methods in single study\",\n      \"pmids\": [\"20133788\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"ASF1a and ASF1b, which arose by gene duplication at the ancestor of jawed vertebrates, have distinct preferential interactions with different H3-H4 chaperones; regions outside the primary interaction surface (in the N- and C-terminal regions) are key determinants of these preferential interactions, as demonstrated by biochemical and structural analyses.\",\n      \"method\": \"Biochemical binding assays, structural analysis, evolutionary/comparative genomics, positive selection analysis\",\n      \"journal\": \"Molecular biology and evolution\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — structural and biochemical approaches combined, but abstracts do not fully detail reconstitution or mutagenesis specifics for ASF1B specifically\",\n      \"pmids\": [\"23645555\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"ASF1B promotes human β-cell proliferation in a histone-binding-dependent manner; the histone-binding-deficient mutant V94R fails to induce proliferation. Co-expression of histone H3.3 (but not H3.1 or H3.2) synergistically augments ASF1B-mediated β-cell proliferation, and suppression of endogenous H3.3 attenuates the stimulatory effect of ASF1B, establishing that ASF1B requires histone H3.3 binding for its proliferative function.\",\n      \"method\": \"Overexpression, dominant-negative (V94R) mutant, siRNA knockdown of H3.3, multiple proliferation assays (BrdU, Ki67, mitotic markers)\",\n      \"journal\": \"Cell cycle (Georgetown, Tex.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — active-site/binding-domain mutagenesis (V94R) combined with co-expression and KD experiments with multiple orthogonal readouts in a single study\",\n      \"pmids\": [\"27753532\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Loss of ASF1B in mice reduces female reproductive capacity; ASF1B is specifically expressed in germ cells with peak expression correlating with meiosis, and Asf1b-null female mice show altered timing of meiotic entry and defective gonad development, indicating ASF1B plays a role in chromatin modifications at meiotic entry.\",\n      \"method\": \"Asf1b gene-trap knockout mouse, β-galactosidase reporter assay, histological analysis, reproductive phenotyping\",\n      \"journal\": \"Reproduction (Cambridge, England)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO model with defined reproductive/meiotic phenotype, but molecular mechanism downstream of ASF1B loss not fully resolved at molecular level from abstract\",\n      \"pmids\": [\"26850882\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"ASF1B forms stable complexes with CDK9 and positively regulates CDK9 stabilization in cervical cancer cells; ASF1B knockdown reduces CDK9 protein levels.\",\n      \"method\": \"Co-immunoprecipitation, Western blot, siRNA knockdown, in vivo tumor xenograft model\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — Co-IP demonstrating complex formation and KD showing reduced CDK9 stability, replicated in vivo, but stabilization mechanism not biochemically dissected\",\n      \"pmids\": [\"32848135\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Asf1a, but not Asf1b, is required for histone H3.3 assembly in the paternal pronucleus after fertilization. Knockdown of Asf1b (but not Asf1a) nearly eliminates nuclear accumulation of PCNA in morula-stage embryos, indicating ASF1B specifically safeguards pre-implantation embryo development by regulating cell proliferation, while Asf1a regulates H3K56ac levels and Oct4 expression.\",\n      \"method\": \"Morpholino-mediated knockdown, immunofluorescence with specific antibodies, confocal microscopy in mouse embryos\",\n      \"journal\": \"Epigenetics & chromatin\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — specific Morpholino KD with defined molecular readouts (PCNA, H3.3, H3K56ac), orthogonal to genetic KO data, single lab\",\n      \"pmids\": [\"34906203\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ASF1B knockdown in HCC cells reduces expression of PCNA, cyclinB1, cyclinE2, and CDK9, and ASF1B interacts with CDK9 in HCC cells, consistent with a role for ASF1B-CDK9 complex in cell cycle regulation.\",\n      \"method\": \"Co-immunoprecipitation, Western blot, siRNA knockdown\",\n      \"journal\": \"Frontiers in oncology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP and KD experiment in a single lab, replicates CDK9 interaction finding from PMID:32848135 but with no additional mechanistic depth\",\n      \"pmids\": [\"35087760\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ASF1B knockdown increases S-phase cell cycle arrest and activates checkpoint kinases Chk1 and Chk2, indicating ASF1B normally suppresses replication checkpoint activation in pancreatic cancer cells.\",\n      \"method\": \"siRNA knockdown, flow cytometry cell cycle analysis, Western blot for Chk1/Chk2 phosphorylation\",\n      \"journal\": \"Cancer biomarkers : section A of Disease markers\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, KD with pathway readout but no direct epistasis or reconstitution\",\n      \"pmids\": [\"35599471\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"ASF1B interacts with and occupies the TLK1 gene locus (ChIP assay), and the interaction between ASF1B and TLK1 promotes proliferation, cell cycle progression, and metastasis of low-grade glioma cells; overexpression of TLK1 rescues the effects of ASF1B interference.\",\n      \"method\": \"ChIP assay, co-expression rescue experiments, siRNA knockdown, cell functional assays\",\n      \"journal\": \"Annals of medicine\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — ChIP and rescue experiments, but the molecular nature of ASF1B-TLK1 interaction not biochemically characterized at protein level\",\n      \"pmids\": [\"36947060\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Transcription factor FOXM1 directly binds the ASF1B promoter region and regulates ASF1B transcription. In turn, ASF1B regulates PRDX3 transcription in a FOXM1-dependent manner, forming a FOXM1-ASF1B-PRDX3 axis that controls GC cell proliferation and oxidative stress balance.\",\n      \"method\": \"ChIP assay, FOXM1 inhibitor (thiostrepton) treatment, knockdown/overexpression experiments, in vitro and in vivo tumor models\",\n      \"journal\": \"Cancer letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct promoter binding demonstrated by ChIP, functional axis validated with inhibitor and KD/OE, two orthogonal methods in single study\",\n      \"pmids\": [\"38537775\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"CDAN1 dimerizes and assembles into cytosolic complexes with CDIN1 and multiple copies of ASF1A/B. Cryo-EM structures reveal that CDAN1 engages ASF1B via two B-domains (found in other ASF1-binding partners) and two helices that mimic histone H3 binding. CDAN1 can recruit two ASF1 molecules simultaneously and sequesters/inhibits ASF1 chaperone function; ASF1A and ASF1B have different requirements for CDAN1 engagement.\",\n      \"method\": \"Single-particle cryo-EM, biochemical reconstitution, structural analysis\",\n      \"journal\": \"bioRxiv (preprint)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — cryo-EM structure with biochemical reconstitution; direct structural and mechanistic characterization of the inhibitory complex, preprint not yet peer-reviewed but orthogonal methods within single rigorous study\",\n      \"pmids\": [\"bio_10.1101_2024.08.08.607204\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"ASF1B promotes gastric cancer progression by downregulating histone H2AC20, which activates the PI3K/AKT and ERK1/2 signaling pathways; identified by IP-MS and TMT proteomics to define the ASF1B-interacting protein network.\",\n      \"method\": \"Immunoprecipitation-Mass Spectrometry (IP-MS), TMT proteomics, ASF1B knockout/overexpression, in vitro and in vivo tumor models, organoids\",\n      \"journal\": \"Frontiers in pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — IP-MS identifies interaction partners, functional pathway validated with KO/OE models and in vivo, but direct H2AC20 regulation mechanism not fully mechanistically dissected from abstract\",\n      \"pmids\": [\"40041497\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"ASF1B recruits the transcription factor HOXB3, promoting ZDHHC9 transcription. ZDHHC9 then palmitoylates PCBP1 at residue C109, inhibiting PCBP1 ubiquitination and suppressing SLC7A11-mediated ferroptosis, thus promoting gastric cancer liver metastasis. Identified by immunoprecipitation and LC-MS analyses.\",\n      \"method\": \"Immunoprecipitation/LC-MS, transcriptome sequencing, label-free proteomics, spleen-injection liver metastasis model, IHC, immunofluorescence\",\n      \"journal\": \"NPJ precision oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP/LC-MS for interaction, mechanistic pathway validated by rescue assays, but multiple steps between ASF1B and ferroptosis mean ASF1B-specific mechanistic attribution is indirect\",\n      \"pmids\": [\"41535416\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"ASF1B occupies >70% of H3.3 nucleosomes in mouse fetal liver erythroid cells and determines H3.3 enrichment at erythroid gene promoters and enhancers. ASF1B predominantly regulates H3.3-encoding genes and erythroid genes (with ASF1A serving a compensatory function). Loss of ASF1B de-represses embryonic/fetal globin genes by altering H3.3 enrichment, erythroid transcription factor binding, and chromatin accessibility. The regulatory pathway involves recruitment of chromatin remodeler BRG1 and accumulation of H3K27ac at active chromatin.\",\n      \"method\": \"ChIP-seq, ATAC-seq, ASF1B knockout in mouse fetal liver cells, transcriptome sequencing, co-immunoprecipitation for BRG1 interaction\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — genome-wide ChIP-seq directly maps ASF1B to H3.3 nucleosomes, KO shows functional consequences at chromatin and transcriptional level, BRG1 recruitment validated; multiple orthogonal methods in single rigorous study\",\n      \"pmids\": [\"42100853\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"ASF1B recruits the lactyltransferase p300, thereby promoting histone H3K18 lactylation (H3K18la) in hepatocellular carcinoma cells, forming a positive feedback loop with H3K18la.\",\n      \"method\": \"Co-immunoprecipitation, ChIP sequencing, Cut&Run, dual-luciferase reporter assay\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — Co-IP demonstrates ASF1B-p300 interaction and ChIP shows H3K18la changes, but mechanistic detail of how ASF1B recruits p300 is not fully characterized from abstract\",\n      \"pmids\": [\"42193960\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ASF1B is a histone H3-H4 chaperone that functions primarily during DNA replication and cell proliferation: it occupies H3.3 nucleosomes genome-wide, recruits chromatin remodelers (BRG1) and histone modifiers (p300/H3K18la), is transcriptionally activated by FOXM1, is inhibited by CDAN1 via a structural mimicry mechanism (sequestering ASF1B in cytosolic complexes), interacts with CDK9 to promote its stabilization, is coupled to DNA replication machinery via HCF-1, and requires intact histone-binding capacity (V94R-sensitive) and H3.3 to drive cell proliferation; its loss activates replication checkpoints (Chk1/Chk2) and in vivo impairs meiosis and erythropoiesis.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ASF1B is a histone H3-H4 chaperone with a specific, non-redundant role in cell proliferation and chromatin assembly during DNA replication [#0, #3]. Its activity depends on intact histone-binding capacity—the V94R binding-deficient mutant fails to drive proliferation—and on histone H3.3 in particular, which synergizes with ASF1B and is required for its proliferative effect [#3]. Genome-wide, ASF1B occupies the majority of H3.3 nucleosomes and determines H3.3 enrichment at promoters and enhancers, working with the chromatin remodeler BRG1 and H3K27ac to control lineage gene programs; its loss de-represses developmentally silenced genes [#14]. ASF1B is functionally coupled to replication machinery via HCF-1, with which it co-localizes at replication foci, and its depletion impairs DNA replication [#1]. Diverging from the paralog ASF1A, ASF1B carries distinct N- and C-terminal determinants that specify preferential chaperone interactions [#2], and it is selectively required to sustain proliferation, such that loss triggers S-phase arrest and Chk1/Chk2 checkpoint activation [#0, #8]. ASF1B chaperone function is held in check by CDAN1, which assembles cytosolic complexes that sequester ASF1B through two B-domains and histone-H3-mimicking helices [#11]. In proliferative and oncogenic contexts ASF1B is transcriptionally induced by FOXM1 and feeds forward to regulate downstream effectors such as PRDX3 [#10], stabilizes CDK9 [#5], and recruits chromatin modifiers including the lactyltransferase p300 to promote H3K18 lactylation [#15]. In vivo, ASF1B is required for normal meiotic entry and gonad development and for pre-implantation embryo proliferation [#4, #6].\",\n  \"teleology\": [\n    {\n      \"year\": 2010,\n      \"claim\": \"Established that ASF1B, distinct from ASF1A, is specifically required for cell proliferation, defining its core biological role rather than treating the two paralogs as interchangeable.\",\n      \"evidence\": \"siRNA depletion, cell-cycle exit assays, and transcriptional profiling in cultured cells\",\n      \"pmids\": [\"21179005\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of the ASF1B-specific requirement not resolved\", \"Did not define genome-wide chromatin targets\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Linked ASF1B to active DNA replication by showing it acts downstream of HCF-1 at replication foci, connecting the chaperone to the replication machinery.\",\n      \"evidence\": \"Co-IP, immunofluorescence co-localization, and siRNA depletion with viral DNA quantification in HSV infection\",\n      \"pmids\": [\"20133788\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Demonstrated in a viral replication context; relevance to cellular replication inferred\", \"Mechanism of chromatin reorganization downstream of HCF-1 not detailed\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Explained why ASF1A and ASF1B are non-redundant by mapping divergent N- and C-terminal regions outside the core interface that specify distinct chaperone partnerships.\",\n      \"evidence\": \"Biochemical binding assays, structural analysis, and evolutionary/positive-selection analysis\",\n      \"pmids\": [\"23645555\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"ASF1B-specific reconstitution and mutagenesis details limited\", \"Functional consequences of preferential interactions not tested in cells\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Defined the molecular requirement for ASF1B proliferative function as histone binding and specifically H3.3, not H3.1/H3.2.\",\n      \"evidence\": \"Overexpression, V94R binding-deficient mutant, H3.3 knockdown, and multiple proliferation readouts in human beta-cells\",\n      \"pmids\": [\"27753532\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream chromatin events of ASF1B-H3.3 deposition not mapped\", \"Restricted to beta-cell model\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Demonstrated an in vivo developmental role, showing ASF1B is required for normal meiotic entry timing and gonad development.\",\n      \"evidence\": \"Asf1b gene-trap knockout mouse with beta-gal reporter, histology, and reproductive phenotyping\",\n      \"pmids\": [\"26850882\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular mechanism downstream of ASF1B loss in germ cells not resolved\", \"Chromatin targets in meiosis not identified\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Separated ASF1A and ASF1B roles in early embryogenesis, attributing proliferation maintenance (PCNA accumulation) to ASF1B and paternal H3.3 assembly to ASF1A.\",\n      \"evidence\": \"Morpholino knockdown with immunofluorescence for PCNA, H3.3, and H3K56ac in mouse embryos\",\n      \"pmids\": [\"34906203\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab morpholino approach\", \"Direct mechanism linking ASF1B to PCNA accumulation not defined\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Identified CDK9 as an ASF1B partner that ASF1B stabilizes, extending ASF1B function into cell-cycle/transcriptional kinase regulation in cancer.\",\n      \"evidence\": \"Co-IP, Western blot, siRNA knockdown, and xenograft model in cervical cancer cells\",\n      \"pmids\": [\"32848135\", \"35087760\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Biochemical mechanism of CDK9 stabilization not dissected\", \"Whether stabilization requires histone-chaperone activity unknown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Placed ASF1B upstream of the replication checkpoint, showing its loss causes S-phase arrest and Chk1/Chk2 activation.\",\n      \"evidence\": \"siRNA knockdown, flow cytometry cell-cycle analysis, and Chk1/Chk2 phospho-Western in pancreatic cancer cells\",\n      \"pmids\": [\"35599471\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No epistasis or reconstitution to establish directness\", \"Single-lab observational link\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Defined an upstream transcriptional driver, showing FOXM1 directly activates ASF1B which then regulates PRDX3, embedding ASF1B in a proliferation/oxidative-stress axis.\",\n      \"evidence\": \"ChIP, FOXM1 inhibitor (thiostrepton), knockdown/overexpression, and in vitro/in vivo gastric cancer models\",\n      \"pmids\": [\"38537775\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which ASF1B controls PRDX3 transcription unclear\", \"Whether axis is gastric-cancer-specific not addressed\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Provided a structural mechanism for ASF1B inhibition, showing CDAN1/CDIN1 sequester ASF1B via B-domains and histone-H3-mimicking helices.\",\n      \"evidence\": \"Single-particle cryo-EM and biochemical reconstitution of CDAN1-ASF1 complexes (preprint)\",\n      \"pmids\": [\"bio_10.1101_2024.08.08.607204\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cellular consequences of CDAN1 sequestration on ASF1B function not quantified\", \"Preprint, not peer-reviewed\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Delivered the genome-wide chaperone model, mapping ASF1B to most H3.3 nucleosomes and showing it controls H3.3 enrichment, BRG1 recruitment, and lineage gene repression in erythropoiesis.\",\n      \"evidence\": \"ChIP-seq, ATAC-seq, transcriptome sequencing, BRG1 Co-IP, and ASF1B knockout in mouse fetal liver erythroid cells\",\n      \"pmids\": [\"42100853\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How ASF1B selects H3.3 sites genome-wide not defined\", \"Extent of ASF1A compensation across loci incomplete\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Extended ASF1B to chromatin-modifier recruitment, showing it brings p300 to chromatin to promote H3K18 lactylation in HCC.\",\n      \"evidence\": \"Co-IP, ChIP-seq, Cut&Run, and dual-luciferase reporter in hepatocellular carcinoma cells\",\n      \"pmids\": [\"42193960\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of ASF1B-p300 recruitment not characterized\", \"Direct vs indirect H3K18la control unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How ASF1B achieves H3.3-selective, locus-specific deposition and integrates its chaperone activity with its many reported cancer signaling partners remains unresolved.\",\n      \"evidence\": null,\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model linking histone-chaperone function to CDK9/HOXB3/p300 effects\", \"Determinants of ASF1B target-site specificity unknown\", \"Whether oncogenic functions require intact histone binding largely untested\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0042393\", \"supporting_discovery_ids\": [3, 14]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [1, 14]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 14]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [11]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [14, 15]},\n      {\"term_id\": \"R-HSA-69306\", \"supporting_discovery_ids\": [1, 8]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [0, 8]}\n    ],\n    \"complexes\": [\"CDAN1-CDIN1-ASF1 cytosolic complex\"],\n    \"partners\": [\"HCF-1\", \"CDK9\", \"CDAN1\", \"CDIN1\", \"BRG1\", \"p300\", \"HOXB3\", \"TLK1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}