{"gene":"DNMT3B","run_date":"2026-06-09T23:54:42","timeline":{"discoveries":[{"year":1999,"finding":"Dnmt3b functions as a de novo DNA methyltransferase essential for mouse development; genetic knockout blocks de novo methylation in ES cells and early embryos, and Dnmt3b is specifically required for methylation of centromeric minor satellite repeats.","method":"Gene targeting (knockout mice), bisulfite sequencing, methylation analysis of ES cells and embryos","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic KO with defined molecular phenotype, replicated across multiple cell types and developmental stages, foundational paper widely confirmed","pmids":["10555141"],"is_preprint":false},{"year":1999,"finding":"Missense mutations and a splice-site insertion in DNMT3B cause ICF syndrome, characterized by hypomethylation of pericentromeric satellite repeats on chromosomes 1, 9, and 16; somatic cell fusion complemented the hypomethylation defect, indicating DNMT3B promotes de novo methylation at these loci.","method":"Mutation screening of ICF patients, somatic cell fusion complementation assay, bisulfite methylation analysis","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — human genetics combined with complementation assay, replicated across multiple families","pmids":["10588719"],"is_preprint":false},{"year":2002,"finding":"DNMT3B cooperates with DNMT1 to maintain DNA methylation and gene silencing in human cancer cells; disruption of both DNMT1 and DNMT3B reduced genomic methylation by >95%, demethylated repeated sequences, abolished IGF2 imprinting, and relieved p16INK4a silencing, whereas loss of DNMT3B alone reduced methylation by less than 3%.","method":"Targeted gene disruption in colorectal cancer cells, methyltransferase activity assays, bisulfite sequencing, gene expression analysis","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic disruption with multiple orthogonal readouts in human cells, highly replicated","pmids":["11932749"],"is_preprint":false},{"year":2004,"finding":"DNMT3L stimulates the DNA methylation activity of Dnmt3b (and Dnmt3a) approximately 1.5–3-fold through a direct protein–protein interaction; the C-terminal half of DNMT3L is responsible for this stimulation, and DNMT3L cannot bind DNA directly, indicating the effect is on catalytic activity rather than DNA targeting.","method":"In vitro methyltransferase activity assays, direct binding assays, domain deletion analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with domain mutagenesis, single lab but multiple orthogonal methods","pmids":["15105426"],"is_preprint":false},{"year":2007,"finding":"Dnmt3a and Dnmt3b form a native complex in embryonic stem cells, directly interact and mutually stimulate each other's methyltransferase activity both in vitro and in vivo (stimulatory effect is independent of catalytic activity), and synergistically methylate the Oct4 and Nanog promoters during differentiation.","method":"Native complex purification from ES cells, Co-IP, in vitro methylation assays with catalytic mutants, bisulfite sequencing in differentiating cells and embryos","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — native complex purification, reciprocal Co-IP, in vitro activity assays with mutants, and in vivo cellular validation in single study","pmids":["17938196"],"is_preprint":false},{"year":2008,"finding":"miR-148 represses DNMT3B expression through a target site in the protein-coding region (present in splice variants Dnmt3b1, Dnmt3b2, Dnmt3b4 but not Dnmt3b3); mutation of the target site abolished regulation, and Dnmt3b3 (lacking the site) is resistant to miR-148-mediated repression.","method":"miRNA overexpression and shRNA knockdown, site-directed mutagenesis of target site, mRNA/protein quantification","journal":"RNA","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional mutagenesis of target site and isoform controls in single lab, two orthogonal approaches","pmids":["18367714"],"is_preprint":false},{"year":2009,"finding":"The RNA-binding protein HuR binds the 3'UTR of DNMT3B mRNA, stabilizes it, and increases DNMT3B protein levels and global DNA methylation; cisplatin treatment triggers dissociation of the HuR–DNMT3B mRNA complex, promoting DNMT3B mRNA decay and reducing global methylation.","method":"Endogenous HuR RNP immunoprecipitation, in vitro biotinylated RNA pulldown/western blot, mRNA stability assays, global methylation analysis","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal pulldown and IP, mRNA stability assays, functional methylation readout, single lab","pmids":["19270063"],"is_preprint":false},{"year":2010,"finding":"DNMT3B associates with NEDD8-modified proteins in vivo, preferentially interacts with NEDDylated CUL4A (among cullins CUL1–5), and NEDD8 enhances DNMT3B-dependent DNA methylation; DNMT3B recruits CUL4A and NEDD8 to chromatin at a repressed promoter.","method":"Co-immunoprecipitation, in vitro direct binding assay with NEDD8, chromatin immunoprecipitation, deletion of Dnmt3b in cancer cell line","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP and in vitro direct binding, ChIP validation, single lab","pmids":["20847044"],"is_preprint":false},{"year":2012,"finding":"DNMT3A and DNMT3B function as redox-dependent DNA 5-hydroxymethylcytosine dehydroxymethylases in vitro, directly converting 5-hmC to cytosine; the catalytic methylation sites of these enzymes are required for 5-hmC dehydroxymethylation activity.","method":"In vitro biochemical dehydroxymethylation assay, active-site mutagenesis","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro reconstitution with mutagenesis, single lab, not yet independently replicated in this corpus","pmids":["22898819"],"is_preprint":false},{"year":2013,"finding":"Catalytically inactive DNMT3B3 modestly stimulates DNMT3A and counteracts DNMT3L stimulation; catalytically inactive DNMT3B4 significantly inhibits de novo DNA methylation by active DNMT3 enzymes by reducing their DNA-binding affinity. Both inactive isoforms also drive distinct chromatin compaction and H3K9me3 patterns.","method":"Biochemical in vitro methylation assays, DNA binding affinity assays, immunocytochemistry for H3K9me3","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with multiple isoforms and multiple substrates, single lab, two orthogonal readouts","pmids":["23894490"],"is_preprint":false},{"year":2016,"finding":"DNMT3B loss in melanoma results in hypomethylation of the miR-196b promoter, increased miR-196b expression, which directly targets the mTORC2 component RICTOR, reducing mTORC2 activation and suppressing melanoma formation in a Braf/Pten mouse model.","method":"Conditional knockout mouse model, bisulfite sequencing of miR-196b promoter, miR-196b target validation (luciferase/western blot), genetic epistasis with RICTOR","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo KO model with pathway epistasis, bisulfite sequencing and target validation, single lab","pmids":["26923591"],"is_preprint":false},{"year":2016,"finding":"Catalytically inactive DNMT3B isoforms stimulate gene body methylation and re-methylation after demethylation-inhibitor treatment independently of their own catalytic activity, functioning as accessory proteins analogous to DNMT3L to recruit DNMT3A in somatic cells.","method":"Cellular re-methylation assays after 5-aza treatment, catalytic mutant isoform expression, genome-wide methylation analysis","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple isoform comparisons with catalytic mutants, genome-wide methylation readout, single lab","pmids":["27121154"],"is_preprint":false},{"year":2016,"finding":"In human epidermal stem cells, Dnmt3b binds active enhancers in an H3K36me3-dependent manner and promotes DNA methylation along enhancer bodies; Dnmt3b depletion inactivates target enhancers and impairs epidermal stem cell function.","method":"ChIP-seq for endogenous Dnmt3a/3b, RRBS methylation analysis, enhancer RNA measurement, shRNA depletion with stem cell functional assays","journal":"Cell stem cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP-seq and methylation genome-wide with functional KD, single lab but multiple orthogonal methods","pmids":["27476967"],"is_preprint":false},{"year":2017,"finding":"DNMT3B preferentially mediates non-CpG methylation of REST-targeted RE1 sequences in developing mouse hearts; loss of DNMT3B reduces non-CpG methylation at RE1 sites, decreases REST occupancy, and releases transcriptional suppression of adult cardiac genes.","method":"Mouse genetic models (Dnmt3b KO), bisulfite sequencing (CpG and non-CpG), ChIP for REST occupancy, gene expression analysis","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo KO with orthogonal ChIP and methylation analyses, single lab","pmids":["27956497"],"is_preprint":false},{"year":2019,"finding":"Catalytically inactive Dnmt3b restores the majority of methylation and expression changes in Dnmt3b-null embryos, rescuing embryonic lethality, demonstrating that Dnmt3b functions as an accessory cofactor supporting other DNMTs; Dnmt3b also directly represses Wnt9b as a transcriptional repressor independent of its catalytic activity.","method":"Knock-in of catalytically inactive Dnmt3b in mice, genome-wide methylation, transcriptome analysis, rescue of embryonic lethality","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo catalytic knock-in rescue with genome-wide methylation and transcriptomics, provides definitive evidence for non-catalytic roles","pmids":["31558711"],"is_preprint":false},{"year":2020,"finding":"Comprehensive structural and enzymological analysis revealed that a hydrogen bond in the catalytic loop of DNMT3B causes lower CpG specificity than DNMT3A; interplay of the target recognition domain and homodimeric interface fine-tunes distinct target selection, with Lysine 777 of DNMT3B acting as a unique sensor of the +1 flanking base.","method":"Crystal structures, in vitro methylation activity assays, site-directed mutagenesis, cellular methylation profiling","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structures combined with in vitro enzymology and mutagenesis plus cellular validation in single comprehensive study","pmids":["32620778"],"is_preprint":false},{"year":2020,"finding":"Cryo-EM structure of DNMT3A2–DNMT3B3–nucleosome ternary complex showed that the catalytic-like domain of accessory DNMT3B3 binds the acidic patch of the nucleosome core, orienting DNMT3A2 toward linker DNA; steric constraints suggest nucleosomal DNA must be repositioned for methylation.","method":"Cryo-electron microscopy structure determination, functional validation of binding","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — cryo-EM structure at high resolution providing direct mechanistic insight, single study but Tier 1 method","pmids":["32968275"],"is_preprint":false},{"year":2020,"finding":"DNMT3B catalytic domain methylation rates at non-CpG sites are more strongly affected by flanking sequences than at CpG sites; T775 has an essential dynamic role in the catalytic mechanism; six residues (N652, N656, N658, K777, N779, R823) in the DNA-binding interface equalize methylation rates across favored and disfavored sequence contexts.","method":"In vitro methylation of substrate pools with randomized flanking sequences, mutagenesis of active-site and interface residues","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with comprehensive mutagenesis of multiple residues, single lab","pmids":["33105482"],"is_preprint":false},{"year":2020,"finding":"The catalytically inactive Dnmt3b3 isoform positively regulates de novo methylation by Dnmt3a and Dnmt3b (preferring Dnmt3b), is as potent as Dnmt3L in stimulating activities of Dnmt3a2 and Dnmt3b2 in vitro, and forms a 2:2 complex with Dnmt3a2; rescue experiments in triple-KO mESCs confirm Dnmt3b3 preferentially supports Dnmt3b2 over Dnmt3a2.","method":"In vitro methylation activity assays, stoichiometry analysis, rescue experiments in Dnmt3a/3b/3l triple-KO mESCs, genome-wide methylation","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — in vitro reconstitution combined with genetic rescue in KO cells and genome-wide methylation, single lab with multiple orthogonal methods","pmids":["33004415"],"is_preprint":false},{"year":2016,"finding":"Dnmt3b-C methylates DNA by a non-cooperative (processive) mechanism, in contrast to the cooperative mechanism of Dnmt3a-C; manipulations at the predicted dimer interface (including the R829H mutation analogous to the AML-associated R882H in DNMT3A) do not affect Dnmt3b-C activity or processivity, indicating dimer interface interactions play a limited role in regulating Dnmt3b.","method":"In vitro methylation kinetics assays distinguishing cooperativity from processivity, site-directed mutagenesis (R829H), buffer acidification experiments","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with mutagenesis and kinetic analysis, mechanistically distinct from DNMT3A, single lab","pmids":["27768276"],"is_preprint":false},{"year":2022,"finding":"Cryo-EM structure of the DNMT3B methyltransferase homo-oligomer reveals an FF interface whose interplay with the catalytic loop confers conformation and activity distinct from the DNMT3B–DNMT3L heterotetramer; ICF mutations at the FF interface impair DNA binding and heterochromatin targeting of DNMT3B, reducing DNA methylation in cells.","method":"Cryo-EM structure of homo-oligomer, biochemical DNA binding assays, cellular ChIP and methylation analyses with ICF mutants","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — cryo-EM structure with biochemical and cellular validation using disease mutations, multiple orthogonal methods","pmids":["35869095"],"is_preprint":false},{"year":2023,"finding":"Cryo-EM structures of DNMT3B under various oligomerization states reveal that the ADD domain interacts with the MTase domain to form an autoinhibitory conformation; the PWWP domain allosterically regulates DNMT3B tetramer assembly; ADD-H3K4me0 and PWWP-H3K36me3 bindings differentially impact DNMT3B activity; oligomerization is coupled to folding of substrate-binding sites.","method":"Cryo-EM structure determination under multiple oligomerization states, biochemical activity assays, domain interaction analyses","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Moderate — cryo-EM structures under multiple conditions combined with biochemistry, single study but Tier 1 methods","pmids":["37941146"],"is_preprint":false},{"year":2018,"finding":"Dnmt3b deletion in mesenchymal progenitor cells (Prx1-Cre) impairs fracture repair and chondrogenic/osteogenic differentiation; Dnmt3b directly binds two sites in the Rbpjκ promoter/gene body (confirmed by ChIP), repressing Notch signaling; Rbpjκ inhibition restored MPC differentiation in Dnmt3b-null cells.","method":"Conditional KO mice (Prx1-Cre), ChIP assay for Dnmt3b binding to Rbpjκ, luciferase reporter assay, in vitro differentiation assays, pharmacological Rbpjκ inhibition rescue","journal":"JCI insight","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo KO with ChIP-defined binding site, luciferase validation, and epistasis rescue, single lab","pmids":["32051335"],"is_preprint":false},{"year":2014,"finding":"Dnmt3b combined loss with Dnmt3a in HSCs synergistically enhances self-renewal and blocks differentiation more severely than Dnmt3a loss alone; the predominant Dnmt3b isoform in adult HSCs is catalytically inactive yet its residual activity in Dnmt3a-null HSCs drives some differentiation and generates paradoxical CpG island hypermethylation; combined Dnmt3a/3b loss activates β-catenin signaling.","method":"Conditional KO mice (alone and combined), HSC transplantation assays, whole-genome bisulfite sequencing, pathway analysis","journal":"Cell stem cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo conditional double KO with genome-wide methylation and functional transplantation readout, well-controlled genetic epistasis","pmids":["25130491"],"is_preprint":false},{"year":2023,"finding":"DNMT3B (not DNMT3A or DNMT3L) is specifically required in placental trophoblast lineages to silence germline genes and for formation of the maternal-fetal interface in the placental labyrinth; Sox2-Cre deletion of Dnmt3b only in the embryo (sparing placenta) rescued placental phenotype and embryonic lethality, demonstrating that the embryonic lethality of Dnmt3b-null mice is primarily caused by placental defects.","method":"Conditional KO using Sox2-Cre vs global KO, whole-genome bisulfite sequencing, transcriptome analysis, histology of placenta","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — tissue-specific genetic rescue with genome-wide methylomics and transcriptomics, rigorous epistatic controls","pmids":["36690623"],"is_preprint":false},{"year":2024,"finding":"DNMT1 and DNMT3B (but not DNMT3A) cooperate to maintain DNA methylation; inducible DNMT1 degradation in human cells causes progressive passive demethylation, and loss of DNAme is accompanied by reversible changes in heterochromatin organization, genome compartmentalization, and peripheral localization.","method":"Inducible DNMT1 degradation (dTAG system), whole-genome bisulfite sequencing, Hi-C, lamina-associated domain analysis, live imaging","journal":"The Journal of cell biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — inducible system with multiple orthogonal readouts, single lab, reveals DNMT3B-specific (not DNMT3A) cooperation","pmids":["38376465"],"is_preprint":false},{"year":2019,"finding":"Mahanine induces proteasomal degradation of DNMT3B (and DNMT1) via Akt inactivation; Akt physically interacts with DNMT3B, and disruption of this interaction (by mahanine or wortmannin) leads to DNMT3B degradation; constitutively active Akt prevents mahanine-induced DNMT3B loss, linking Akt signaling to DNMT3B protein stability.","method":"Co-immunoprecipitation of Akt–DNMT3B interaction, proteasome inhibitor rescue (MG132), constitutively active Akt overexpression, ubiquitination detection","journal":"Molecular cancer","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP of interaction, functional rescue with multiple genetic and pharmacological tools, single lab","pmids":["24001151"],"is_preprint":false},{"year":2017,"finding":"Rbm10-mediated alternative splicing controls the ratio of catalytically active Dnmt3b2 to inactive Dnmt3b3; Rbm10 deficiency increases Dnmt3b2 expression, leading to hypermethylation of NF-κB-responsive promoters and reduced NF-κB recruitment, thereby suppressing inflammatory gene expression.","method":"Rbm10 knockout mouse model and cell lines, RT-PCR for isoform ratios, bisulfite sequencing of NF-κB target promoters, ChIP for NF-κB occupancy, overexpression of Dnmt3b2","journal":"International immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo KO with isoform-specific overexpression, ChIP, and methylation analyses, single lab","pmids":["29309623"],"is_preprint":false},{"year":2022,"finding":"DNMT3B dysfunction (KO or ICF mutations) leads to reduced steady-state (peri-)centromeric R-loops, which become susceptible to XPG/XPF endonuclease cleavage generating DNA breaks at centromeric satellite repeats; error-prone end-joining repairs these DSBs, causing chromosomal instability.","method":"DNMT3B KO cells and ICF patient cells, genome-wide ChIP-seq mapping DNA damage sites, R-loop immunofluorescence, endonuclease inhibition experiments, end-joining repair analysis","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genome-wide ChIP-seq with functional inhibition of endonucleases, single lab but multiple orthogonal methods","pmids":["35688824"],"is_preprint":false}],"current_model":"DNMT3B is a de novo DNA methyltransferase that establishes methylation at centromeric repeats, gene bodies, and enhancers during embryogenesis; it operates via a non-cooperative (processive) catalytic mechanism with distinct flanking-sequence preferences from DNMT3A, is allosterically regulated through ADD-domain autoinhibition and PWWP-domain-dependent oligomerization, is stimulated by DNMT3L and by catalytically inactive isoforms (including Dnmt3b3), cooperates with DNMT1 (but not DNMT3A) for maintenance methylation, binds NEDDylated CUL4A and nucleosome acidic patches to target chromatin, and also functions as a non-catalytic accessory cofactor and direct transcriptional repressor during embryonic development."},"narrative":{"mechanistic_narrative":"DNMT3B is a de novo DNA methyltransferase that establishes cytosine methylation at centromeric satellite repeats, gene bodies, and active enhancers during embryonic and tissue development [PMID:10555141, PMID:27476967]. Genetic ablation in mice blocks de novo methylation and is specifically required for methylation of centromeric minor satellite repeats [PMID:10555141], and missense and splice mutations in DNMT3B cause ICF syndrome, characterized by pericentromeric satellite hypomethylation [PMID:10588719]. Structurally, DNMT3B operates by a non-cooperative (processive) catalytic mechanism distinct from DNMT3A, with a catalytic-loop hydrogen bond and a unique +1 flanking-base sensor (Lys777) that confer lower CpG specificity and characteristic flanking-sequence preferences [PMID:32620778, PMID:27768276]. Its activity is allosterically gated by an autoinhibitory ADD-MTase interaction and by PWWP-dependent oligomerization, with chromatin reading through ADD-H3K4me0 and PWWP-H3K36me3 binding [PMID:37941146], and ICF mutations at the FF homo-oligomerization interface impair DNA binding and heterochromatin targeting [PMID:35869095]. DNMT3B is stimulated by DNMT3L and by catalytically inactive isoforms such as DNMT3B3, which acts as a DNMT3L-like accessory factor that forms a 2:2 complex with DNMT3A2 and preferentially supports DNMT3B2 [PMID:15105426, PMID:33004415]; the inactive DNMT3B3 domain docks onto the nucleosome acidic patch to orient the catalytic enzyme toward linker DNA [PMID:32968275]. Beyond catalysis, DNMT3B functions as a non-catalytic accessory cofactor — catalytically dead DNMT3B rescues most methylation defects and embryonic lethality of Dnmt3b-null embryos — and as a direct transcriptional repressor of genes including Wnt9b [PMID:31558711]. It cooperates with DNMT1 (but not DNMT3A) for maintenance methylation [PMID:38376465], and DNMT3B loss destabilizes centromeric R-loops, generating endonuclease-driven breaks and chromosomal instability [PMID:35688824]. Its expression is post-transcriptionally controlled by miR-148, HuR, Rbm10-dependent splicing, and Akt-coupled protein stability [PMID:18367714, PMID:19270063, PMID:24001151, PMID:29309623].","teleology":[{"year":1999,"claim":"Established DNMT3B as a developmentally essential de novo methyltransferase with locus specificity, resolving which DNMT initiates methylation at centromeric repeats and linking it to human disease.","evidence":"Knockout mice with bisulfite methylation analysis, plus ICF patient mutation screening with somatic cell fusion complementation","pmids":["10555141","10588719"],"confidence":"High","gaps":["Did not define the catalytic mechanism or sequence preferences","Targeting determinants to centromeric satellite not established"]},{"year":2002,"claim":"Showed DNMT3B acts together with DNMT1 to maintain genomic methylation and silencing in human cells, distinguishing cooperative maintenance from de novo activity.","evidence":"Targeted gene disruption in colorectal cancer cells with methyltransferase assays, bisulfite sequencing, and imprinting/silencing readouts","pmids":["11932749"],"confidence":"High","gaps":["Whether DNMT3A also cooperates with DNMT1 was not resolved here","Molecular basis of DNMT1-DNMT3B cooperation undefined"]},{"year":2004,"claim":"Identified DNMT3L as a direct protein partner that stimulates DNMT3B catalysis rather than its DNA targeting, framing accessory-factor regulation of activity.","evidence":"In vitro methyltransferase and binding assays with DNMT3L domain deletions","pmids":["15105426"],"confidence":"High","gaps":["Structural basis of stimulation not defined","In vivo relevance of the 1.5-3 fold effect unclear"]},{"year":2007,"claim":"Demonstrated that DNMT3A and DNMT3B form a native complex and mutually stimulate activity independent of catalysis, foreshadowing non-catalytic regulatory roles.","evidence":"Native complex purification, reciprocal Co-IP, in vitro activity assays with catalytic mutants, and bisulfite sequencing of Oct4/Nanog promoters","pmids":["17938196"],"confidence":"High","gaps":["Stoichiometry and structure of the complex not determined","Whether DNMT3A-DNMT3B cooperate in vivo for maintenance not addressed"]},{"year":2008,"claim":"Defined post-transcriptional control of DNMT3B by miR-148 acting on the coding region, with isoform-selective escape, explaining differential isoform regulation.","evidence":"miRNA overexpression/knockdown and site-directed mutagenesis of the target site with mRNA/protein quantification","pmids":["18367714"],"confidence":"Medium","gaps":["Physiological contexts where miR-148 controls DNMT3B not mapped","Downstream methylation consequences not measured"]},{"year":2009,"claim":"Showed mRNA stability control of DNMT3B by HuR couples the enzyme to stress signaling, linking transcript half-life to global methylation.","evidence":"Endogenous HuR RNP-IP, biotinylated RNA pulldown, mRNA stability and global methylation assays with cisplatin treatment","pmids":["19270063"],"confidence":"Medium","gaps":["Single lab; signaling pathway driving HuR dissociation incompletely defined","Locus-specific methylation effects not resolved"]},{"year":2010,"claim":"Connected DNMT3B to the NEDDylation/cullin machinery, identifying NEDDylated CUL4A as a partner that enhances DNMT3B-dependent methylation and chromatin recruitment.","evidence":"Co-IP, in vitro NEDD8 binding, ChIP at a repressed promoter, and Dnmt3b deletion in a cancer cell line","pmids":["20847044"],"confidence":"Medium","gaps":["Functional role of CUL4A recruitment in normal development unclear","Whether NEDDylation regulates DNMT3B turnover not addressed"]},{"year":2012,"claim":"Reported an in vitro 5-hmC dehydroxymethylase activity for DNMT3A/3B dependent on their catalytic sites, raising a possible demethylation-related function.","evidence":"In vitro biochemical dehydroxymethylation assay with active-site mutagenesis","pmids":["22898819"],"confidence":"Medium","gaps":["In vitro reconstitution not independently replicated in this corpus","Physiological significance in cells/embryos unestablished"]},{"year":2014,"claim":"Genetic epistasis in HSCs revealed synergy between Dnmt3a and Dnmt3b and that the predominant adult-HSC Dnmt3b isoform is catalytically inactive yet functionally consequential.","evidence":"Conditional single and combined KO mice, HSC transplantation, whole-genome bisulfite sequencing, pathway analysis","pmids":["25130491"],"confidence":"High","gaps":["Mechanism of inactive-isoform contribution not biochemically defined here","How combined loss activates beta-catenin signaling unresolved"]},{"year":2016,"claim":"Distinguished DNMT3B's catalytic mechanism as non-cooperative/processive, unlike DNMT3A, and showed the dimer interface plays a limited regulatory role.","evidence":"In vitro methylation kinetics, R829H mutagenesis (analogous to DNMT3A R882H), and buffer acidification experiments","pmids":["27768276"],"confidence":"High","gaps":["Structural basis of processivity not yet visualized","Whether processivity shapes genomic targeting unaddressed"]},{"year":2016,"claim":"Defined non-catalytic accessory roles of inactive DNMT3B isoforms in stimulating gene-body methylation and recruiting DNMT3A, extending the DNMT3L-like paradigm to somatic cells, and connected DNMT3B to enhancer methylation, REST-directed non-CpG methylation, and melanoma suppression via miR-196b/RICTOR/mTORC2.","evidence":"Re-methylation assays after 5-aza with catalytic-mutant isoforms; ChIP-seq/RRBS at enhancers in epidermal stem cells; Dnmt3b KO hearts with CpG/non-CpG bisulfite and REST ChIP; conditional KO melanoma model with target validation","pmids":["27121154","27476967","27956497","26923591"],"confidence":"Medium","gaps":["Recruitment specificity of inactive isoforms across tissues not unified","Direct versus indirect transcriptional effects partly inferred"]},{"year":2017,"claim":"Established Rbm10-mediated alternative splicing as a controller of the active/inactive DNMT3B isoform ratio with consequences for NF-kB-responsive promoter methylation and inflammation.","evidence":"Rbm10 KO mice and cells, isoform RT-PCR, bisulfite sequencing of NF-kB targets, NF-kB ChIP, Dnmt3b2 overexpression","pmids":["29309623"],"confidence":"Medium","gaps":["Generalizability beyond the inflammatory loci tested unclear","Single lab"]},{"year":2018,"claim":"Showed DNMT3B acts as a direct transcriptional repressor of Rbpjk to control Notch signaling during skeletal progenitor differentiation and fracture repair.","evidence":"Conditional KO mice (Prx1-Cre), ChIP-defined Rbpjk binding, luciferase reporters, differentiation assays, pharmacologic Rbpjk rescue","pmids":["32051335"],"confidence":"Medium","gaps":["Whether repression requires catalysis at Rbpjk not separated","Cofactors mediating repression unidentified"]},{"year":2019,"claim":"Definitively established a catalysis-independent function: a catalytically dead Dnmt3b rescues most methylation, transcriptome changes, and embryonic lethality, and directly represses Wnt9b.","evidence":"Catalytically inactive Dnmt3b knock-in mice with genome-wide methylation and transcriptomics; Akt-DNMT3B interaction Co-IP defining stability control via mahanine","pmids":["31558711","24001151"],"confidence":"High","gaps":["Molecular partners executing the accessory function not fully defined","How Akt regulates DNMT3B ubiquitination mechanistically unresolved"]},{"year":2020,"claim":"Structural and enzymological work explained DNMT3B's distinct CpG specificity and flanking-base sensing, and visualized accessory DNMT3B3 docking on the nucleosome acidic patch to position the active enzyme; rescue in triple-KO mESCs showed DNMT3B3 rivals DNMT3L and preferentially supports DNMT3B2.","evidence":"Crystal structures with enzymology and mutagenesis; randomized-flank in vitro methylation with interface-residue mutagenesis; cryo-EM of DNMT3A2-DNMT3B3-nucleosome; in vitro stoichiometry plus triple-KO mESC rescue and genome-wide methylation","pmids":["32620778","33105482","32968275","33004415"],"confidence":"High","gaps":["How nucleosomal DNA is repositioned for methylation not directly observed","In vivo balance of homo- versus accessory complexes incompletely quantified"]},{"year":2022,"claim":"Cryo-EM of the DNMT3B homo-oligomer defined a distinct FF interface and showed ICF mutations there impair DNA binding and heterochromatin targeting; parallel work linked DNMT3B loss to centromeric R-loop instability.","evidence":"Cryo-EM homo-oligomer structure with DNA-binding and ChIP/methylation assays using ICF mutants; KO/ICF cells with DNA-damage ChIP-seq, R-loop imaging, and endonuclease inhibition","pmids":["35869095","35688824"],"confidence":"High","gaps":["How the homo-oligomer interconverts with heterotetramers in cells unresolved","R-loop instability mechanism downstream of XPG/XPF cleavage not fully mapped"]},{"year":2023,"claim":"Defined the allosteric architecture of DNMT3B — ADD-mediated autoinhibition and PWWP-driven tetramer assembly coupled to substrate-site folding — and showed a placenta-specific requirement underlying embryonic lethality.","evidence":"Cryo-EM under multiple oligomerization states with biochemistry; Sox2-Cre embryo-restricted deletion versus global KO with whole-genome bisulfite, transcriptomics, and placental histology","pmids":["37941146","36690623"],"confidence":"High","gaps":["How histone-mark binding switches activity in chromatin context not fully integrated","Trophoblast-specific targeting determinants undefined"]},{"year":2024,"claim":"Showed DNMT3B specifically (not DNMT3A) cooperates with DNMT1 for maintenance methylation, with demethylation reversibly remodeling heterochromatin and genome compartmentalization.","evidence":"Inducible DNMT1 degradation (dTAG), whole-genome bisulfite sequencing, Hi-C, lamina-associated domain analysis, live imaging","pmids":["38376465"],"confidence":"Medium","gaps":["Direct physical basis of DNMT1-DNMT3B cooperation not shown","Single lab"]},{"year":null,"claim":"How DNMT3B's oligomerization states, accessory-isoform complexes, and histone-mark reading are dynamically coordinated to select specific genomic loci in vivo remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model linking chromatin context to oligomeric state in cells","Recruitment determinants at centromeres versus enhancers versus gene bodies not reconciled","In vivo significance of in vitro 5-hmC dehydroxymethylase activity unestablished"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140097","term_label":"catalytic activity, acting on DNA","supporting_discovery_ids":[0,15,17,19]},{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[20,21,9]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[14,22,13]},{"term_id":"GO:0042393","term_label":"histone binding","supporting_discovery_ids":[21]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[11,18,14]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[12,13,20]},{"term_id":"GO:0000228","term_label":"nuclear chromosome","supporting_discovery_ids":[0,16,28]}],"pathway":[{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[12,20,25]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[14,22,13]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[0,24,23]},{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[28]}],"complexes":["DNMT3A-DNMT3B complex","DNMT3A2-DNMT3B3-nucleosome ternary complex","DNMT3B-DNMT3L heterotetramer","DNMT3B methyltransferase homo-oligomer"],"partners":["DNMT3A","DNMT3L","DNMT1","DNMT3B3","CUL4A","NEDD8","HUR","AKT"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9UBC3","full_name":"DNA (cytosine-5)-methyltransferase 3B","aliases":["DNA methyltransferase HsaIIIB","DNA MTase HsaIIIB","M.HsaIIIB"],"length_aa":853,"mass_kda":95.8,"function":"Required for genome-wide de novo methylation and is essential for the establishment of DNA methylation patterns during development. DNA methylation is coordinated with methylation of histones. May preferentially methylates nucleosomal DNA within the nucleosome core region. May function as transcriptional co-repressor by associating with CBX4 and independently of DNA methylation. Seems to be involved in gene silencing (By similarity). In association with DNMT1 and via the recruitment of CTCFL/BORIS, involved in activation of BAG1 gene expression by modulating dimethylation of promoter histone H3 at H3K4 and H3K9. Isoforms 4 and 5 are probably not functional due to the deletion of two conserved methyltransferase motifs. Functions as a transcriptional corepressor by associating with ZHX1. Required for DUX4 silencing in somatic cells (PubMed:27153398)","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q9UBC3/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/DNMT3B","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/DNMT3B","total_profiled":1310},"omim":[{"mim_id":"620336","title":"ZINC FINGER SWIM DOMAIN-CONTAINING PROTEIN 3; ZSWIM3","url":"https://www.omim.org/entry/620336"},{"mim_id":"619478","title":"FACIOSCAPULOHUMERAL MUSCULAR DYSTROPHY 4, DIGENIC; FSHD4","url":"https://www.omim.org/entry/619478"},{"mim_id":"619440","title":"GLUTAMINE- AND SERINE-RICH PROTEIN 1; 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embryos\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic KO with defined molecular phenotype, replicated across multiple cell types and developmental stages, foundational paper widely confirmed\",\n      \"pmids\": [\"10555141\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Missense mutations and a splice-site insertion in DNMT3B cause ICF syndrome, characterized by hypomethylation of pericentromeric satellite repeats on chromosomes 1, 9, and 16; somatic cell fusion complemented the hypomethylation defect, indicating DNMT3B promotes de novo methylation at these loci.\",\n      \"method\": \"Mutation screening of ICF patients, somatic cell fusion complementation assay, bisulfite methylation analysis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — human genetics combined with complementation assay, replicated across multiple families\",\n      \"pmids\": [\"10588719\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"DNMT3B cooperates with DNMT1 to maintain DNA methylation and gene silencing in human cancer cells; disruption of both DNMT1 and DNMT3B reduced genomic methylation by >95%, demethylated repeated sequences, abolished IGF2 imprinting, and relieved p16INK4a silencing, whereas loss of DNMT3B alone reduced methylation by less than 3%.\",\n      \"method\": \"Targeted gene disruption in colorectal cancer cells, methyltransferase activity assays, bisulfite sequencing, gene expression analysis\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic disruption with multiple orthogonal readouts in human cells, highly replicated\",\n      \"pmids\": [\"11932749\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"DNMT3L stimulates the DNA methylation activity of Dnmt3b (and Dnmt3a) approximately 1.5–3-fold through a direct protein–protein interaction; the C-terminal half of DNMT3L is responsible for this stimulation, and DNMT3L cannot bind DNA directly, indicating the effect is on catalytic activity rather than DNA targeting.\",\n      \"method\": \"In vitro methyltransferase activity assays, direct binding assays, domain deletion analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with domain mutagenesis, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"15105426\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Dnmt3a and Dnmt3b form a native complex in embryonic stem cells, directly interact and mutually stimulate each other's methyltransferase activity both in vitro and in vivo (stimulatory effect is independent of catalytic activity), and synergistically methylate the Oct4 and Nanog promoters during differentiation.\",\n      \"method\": \"Native complex purification from ES cells, Co-IP, in vitro methylation assays with catalytic mutants, bisulfite sequencing in differentiating cells and embryos\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — native complex purification, reciprocal Co-IP, in vitro activity assays with mutants, and in vivo cellular validation in single study\",\n      \"pmids\": [\"17938196\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"miR-148 represses DNMT3B expression through a target site in the protein-coding region (present in splice variants Dnmt3b1, Dnmt3b2, Dnmt3b4 but not Dnmt3b3); mutation of the target site abolished regulation, and Dnmt3b3 (lacking the site) is resistant to miR-148-mediated repression.\",\n      \"method\": \"miRNA overexpression and shRNA knockdown, site-directed mutagenesis of target site, mRNA/protein quantification\",\n      \"journal\": \"RNA\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional mutagenesis of target site and isoform controls in single lab, two orthogonal approaches\",\n      \"pmids\": [\"18367714\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"The RNA-binding protein HuR binds the 3'UTR of DNMT3B mRNA, stabilizes it, and increases DNMT3B protein levels and global DNA methylation; cisplatin treatment triggers dissociation of the HuR–DNMT3B mRNA complex, promoting DNMT3B mRNA decay and reducing global methylation.\",\n      \"method\": \"Endogenous HuR RNP immunoprecipitation, in vitro biotinylated RNA pulldown/western blot, mRNA stability assays, global methylation analysis\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal pulldown and IP, mRNA stability assays, functional methylation readout, single lab\",\n      \"pmids\": [\"19270063\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"DNMT3B associates with NEDD8-modified proteins in vivo, preferentially interacts with NEDDylated CUL4A (among cullins CUL1–5), and NEDD8 enhances DNMT3B-dependent DNA methylation; DNMT3B recruits CUL4A and NEDD8 to chromatin at a repressed promoter.\",\n      \"method\": \"Co-immunoprecipitation, in vitro direct binding assay with NEDD8, chromatin immunoprecipitation, deletion of Dnmt3b in cancer cell line\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP and in vitro direct binding, ChIP validation, single lab\",\n      \"pmids\": [\"20847044\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"DNMT3A and DNMT3B function as redox-dependent DNA 5-hydroxymethylcytosine dehydroxymethylases in vitro, directly converting 5-hmC to cytosine; the catalytic methylation sites of these enzymes are required for 5-hmC dehydroxymethylation activity.\",\n      \"method\": \"In vitro biochemical dehydroxymethylation assay, active-site mutagenesis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro reconstitution with mutagenesis, single lab, not yet independently replicated in this corpus\",\n      \"pmids\": [\"22898819\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Catalytically inactive DNMT3B3 modestly stimulates DNMT3A and counteracts DNMT3L stimulation; catalytically inactive DNMT3B4 significantly inhibits de novo DNA methylation by active DNMT3 enzymes by reducing their DNA-binding affinity. Both inactive isoforms also drive distinct chromatin compaction and H3K9me3 patterns.\",\n      \"method\": \"Biochemical in vitro methylation assays, DNA binding affinity assays, immunocytochemistry for H3K9me3\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with multiple isoforms and multiple substrates, single lab, two orthogonal readouts\",\n      \"pmids\": [\"23894490\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"DNMT3B loss in melanoma results in hypomethylation of the miR-196b promoter, increased miR-196b expression, which directly targets the mTORC2 component RICTOR, reducing mTORC2 activation and suppressing melanoma formation in a Braf/Pten mouse model.\",\n      \"method\": \"Conditional knockout mouse model, bisulfite sequencing of miR-196b promoter, miR-196b target validation (luciferase/western blot), genetic epistasis with RICTOR\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo KO model with pathway epistasis, bisulfite sequencing and target validation, single lab\",\n      \"pmids\": [\"26923591\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Catalytically inactive DNMT3B isoforms stimulate gene body methylation and re-methylation after demethylation-inhibitor treatment independently of their own catalytic activity, functioning as accessory proteins analogous to DNMT3L to recruit DNMT3A in somatic cells.\",\n      \"method\": \"Cellular re-methylation assays after 5-aza treatment, catalytic mutant isoform expression, genome-wide methylation analysis\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple isoform comparisons with catalytic mutants, genome-wide methylation readout, single lab\",\n      \"pmids\": [\"27121154\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"In human epidermal stem cells, Dnmt3b binds active enhancers in an H3K36me3-dependent manner and promotes DNA methylation along enhancer bodies; Dnmt3b depletion inactivates target enhancers and impairs epidermal stem cell function.\",\n      \"method\": \"ChIP-seq for endogenous Dnmt3a/3b, RRBS methylation analysis, enhancer RNA measurement, shRNA depletion with stem cell functional assays\",\n      \"journal\": \"Cell stem cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP-seq and methylation genome-wide with functional KD, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"27476967\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"DNMT3B preferentially mediates non-CpG methylation of REST-targeted RE1 sequences in developing mouse hearts; loss of DNMT3B reduces non-CpG methylation at RE1 sites, decreases REST occupancy, and releases transcriptional suppression of adult cardiac genes.\",\n      \"method\": \"Mouse genetic models (Dnmt3b KO), bisulfite sequencing (CpG and non-CpG), ChIP for REST occupancy, gene expression analysis\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo KO with orthogonal ChIP and methylation analyses, single lab\",\n      \"pmids\": [\"27956497\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Catalytically inactive Dnmt3b restores the majority of methylation and expression changes in Dnmt3b-null embryos, rescuing embryonic lethality, demonstrating that Dnmt3b functions as an accessory cofactor supporting other DNMTs; Dnmt3b also directly represses Wnt9b as a transcriptional repressor independent of its catalytic activity.\",\n      \"method\": \"Knock-in of catalytically inactive Dnmt3b in mice, genome-wide methylation, transcriptome analysis, rescue of embryonic lethality\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo catalytic knock-in rescue with genome-wide methylation and transcriptomics, provides definitive evidence for non-catalytic roles\",\n      \"pmids\": [\"31558711\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Comprehensive structural and enzymological analysis revealed that a hydrogen bond in the catalytic loop of DNMT3B causes lower CpG specificity than DNMT3A; interplay of the target recognition domain and homodimeric interface fine-tunes distinct target selection, with Lysine 777 of DNMT3B acting as a unique sensor of the +1 flanking base.\",\n      \"method\": \"Crystal structures, in vitro methylation activity assays, site-directed mutagenesis, cellular methylation profiling\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structures combined with in vitro enzymology and mutagenesis plus cellular validation in single comprehensive study\",\n      \"pmids\": [\"32620778\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Cryo-EM structure of DNMT3A2–DNMT3B3–nucleosome ternary complex showed that the catalytic-like domain of accessory DNMT3B3 binds the acidic patch of the nucleosome core, orienting DNMT3A2 toward linker DNA; steric constraints suggest nucleosomal DNA must be repositioned for methylation.\",\n      \"method\": \"Cryo-electron microscopy structure determination, functional validation of binding\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — cryo-EM structure at high resolution providing direct mechanistic insight, single study but Tier 1 method\",\n      \"pmids\": [\"32968275\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"DNMT3B catalytic domain methylation rates at non-CpG sites are more strongly affected by flanking sequences than at CpG sites; T775 has an essential dynamic role in the catalytic mechanism; six residues (N652, N656, N658, K777, N779, R823) in the DNA-binding interface equalize methylation rates across favored and disfavored sequence contexts.\",\n      \"method\": \"In vitro methylation of substrate pools with randomized flanking sequences, mutagenesis of active-site and interface residues\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with comprehensive mutagenesis of multiple residues, single lab\",\n      \"pmids\": [\"33105482\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"The catalytically inactive Dnmt3b3 isoform positively regulates de novo methylation by Dnmt3a and Dnmt3b (preferring Dnmt3b), is as potent as Dnmt3L in stimulating activities of Dnmt3a2 and Dnmt3b2 in vitro, and forms a 2:2 complex with Dnmt3a2; rescue experiments in triple-KO mESCs confirm Dnmt3b3 preferentially supports Dnmt3b2 over Dnmt3a2.\",\n      \"method\": \"In vitro methylation activity assays, stoichiometry analysis, rescue experiments in Dnmt3a/3b/3l triple-KO mESCs, genome-wide methylation\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — in vitro reconstitution combined with genetic rescue in KO cells and genome-wide methylation, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"33004415\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Dnmt3b-C methylates DNA by a non-cooperative (processive) mechanism, in contrast to the cooperative mechanism of Dnmt3a-C; manipulations at the predicted dimer interface (including the R829H mutation analogous to the AML-associated R882H in DNMT3A) do not affect Dnmt3b-C activity or processivity, indicating dimer interface interactions play a limited role in regulating Dnmt3b.\",\n      \"method\": \"In vitro methylation kinetics assays distinguishing cooperativity from processivity, site-directed mutagenesis (R829H), buffer acidification experiments\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with mutagenesis and kinetic analysis, mechanistically distinct from DNMT3A, single lab\",\n      \"pmids\": [\"27768276\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Cryo-EM structure of the DNMT3B methyltransferase homo-oligomer reveals an FF interface whose interplay with the catalytic loop confers conformation and activity distinct from the DNMT3B–DNMT3L heterotetramer; ICF mutations at the FF interface impair DNA binding and heterochromatin targeting of DNMT3B, reducing DNA methylation in cells.\",\n      \"method\": \"Cryo-EM structure of homo-oligomer, biochemical DNA binding assays, cellular ChIP and methylation analyses with ICF mutants\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — cryo-EM structure with biochemical and cellular validation using disease mutations, multiple orthogonal methods\",\n      \"pmids\": [\"35869095\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Cryo-EM structures of DNMT3B under various oligomerization states reveal that the ADD domain interacts with the MTase domain to form an autoinhibitory conformation; the PWWP domain allosterically regulates DNMT3B tetramer assembly; ADD-H3K4me0 and PWWP-H3K36me3 bindings differentially impact DNMT3B activity; oligomerization is coupled to folding of substrate-binding sites.\",\n      \"method\": \"Cryo-EM structure determination under multiple oligomerization states, biochemical activity assays, domain interaction analyses\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — cryo-EM structures under multiple conditions combined with biochemistry, single study but Tier 1 methods\",\n      \"pmids\": [\"37941146\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Dnmt3b deletion in mesenchymal progenitor cells (Prx1-Cre) impairs fracture repair and chondrogenic/osteogenic differentiation; Dnmt3b directly binds two sites in the Rbpjκ promoter/gene body (confirmed by ChIP), repressing Notch signaling; Rbpjκ inhibition restored MPC differentiation in Dnmt3b-null cells.\",\n      \"method\": \"Conditional KO mice (Prx1-Cre), ChIP assay for Dnmt3b binding to Rbpjκ, luciferase reporter assay, in vitro differentiation assays, pharmacological Rbpjκ inhibition rescue\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo KO with ChIP-defined binding site, luciferase validation, and epistasis rescue, single lab\",\n      \"pmids\": [\"32051335\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Dnmt3b combined loss with Dnmt3a in HSCs synergistically enhances self-renewal and blocks differentiation more severely than Dnmt3a loss alone; the predominant Dnmt3b isoform in adult HSCs is catalytically inactive yet its residual activity in Dnmt3a-null HSCs drives some differentiation and generates paradoxical CpG island hypermethylation; combined Dnmt3a/3b loss activates β-catenin signaling.\",\n      \"method\": \"Conditional KO mice (alone and combined), HSC transplantation assays, whole-genome bisulfite sequencing, pathway analysis\",\n      \"journal\": \"Cell stem cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo conditional double KO with genome-wide methylation and functional transplantation readout, well-controlled genetic epistasis\",\n      \"pmids\": [\"25130491\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"DNMT3B (not DNMT3A or DNMT3L) is specifically required in placental trophoblast lineages to silence germline genes and for formation of the maternal-fetal interface in the placental labyrinth; Sox2-Cre deletion of Dnmt3b only in the embryo (sparing placenta) rescued placental phenotype and embryonic lethality, demonstrating that the embryonic lethality of Dnmt3b-null mice is primarily caused by placental defects.\",\n      \"method\": \"Conditional KO using Sox2-Cre vs global KO, whole-genome bisulfite sequencing, transcriptome analysis, histology of placenta\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — tissue-specific genetic rescue with genome-wide methylomics and transcriptomics, rigorous epistatic controls\",\n      \"pmids\": [\"36690623\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"DNMT1 and DNMT3B (but not DNMT3A) cooperate to maintain DNA methylation; inducible DNMT1 degradation in human cells causes progressive passive demethylation, and loss of DNAme is accompanied by reversible changes in heterochromatin organization, genome compartmentalization, and peripheral localization.\",\n      \"method\": \"Inducible DNMT1 degradation (dTAG system), whole-genome bisulfite sequencing, Hi-C, lamina-associated domain analysis, live imaging\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — inducible system with multiple orthogonal readouts, single lab, reveals DNMT3B-specific (not DNMT3A) cooperation\",\n      \"pmids\": [\"38376465\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Mahanine induces proteasomal degradation of DNMT3B (and DNMT1) via Akt inactivation; Akt physically interacts with DNMT3B, and disruption of this interaction (by mahanine or wortmannin) leads to DNMT3B degradation; constitutively active Akt prevents mahanine-induced DNMT3B loss, linking Akt signaling to DNMT3B protein stability.\",\n      \"method\": \"Co-immunoprecipitation of Akt–DNMT3B interaction, proteasome inhibitor rescue (MG132), constitutively active Akt overexpression, ubiquitination detection\",\n      \"journal\": \"Molecular cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP of interaction, functional rescue with multiple genetic and pharmacological tools, single lab\",\n      \"pmids\": [\"24001151\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Rbm10-mediated alternative splicing controls the ratio of catalytically active Dnmt3b2 to inactive Dnmt3b3; Rbm10 deficiency increases Dnmt3b2 expression, leading to hypermethylation of NF-κB-responsive promoters and reduced NF-κB recruitment, thereby suppressing inflammatory gene expression.\",\n      \"method\": \"Rbm10 knockout mouse model and cell lines, RT-PCR for isoform ratios, bisulfite sequencing of NF-κB target promoters, ChIP for NF-κB occupancy, overexpression of Dnmt3b2\",\n      \"journal\": \"International immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo KO with isoform-specific overexpression, ChIP, and methylation analyses, single lab\",\n      \"pmids\": [\"29309623\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"DNMT3B dysfunction (KO or ICF mutations) leads to reduced steady-state (peri-)centromeric R-loops, which become susceptible to XPG/XPF endonuclease cleavage generating DNA breaks at centromeric satellite repeats; error-prone end-joining repairs these DSBs, causing chromosomal instability.\",\n      \"method\": \"DNMT3B KO cells and ICF patient cells, genome-wide ChIP-seq mapping DNA damage sites, R-loop immunofluorescence, endonuclease inhibition experiments, end-joining repair analysis\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genome-wide ChIP-seq with functional inhibition of endonucleases, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"35688824\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"DNMT3B is a de novo DNA methyltransferase that establishes methylation at centromeric repeats, gene bodies, and enhancers during embryogenesis; it operates via a non-cooperative (processive) catalytic mechanism with distinct flanking-sequence preferences from DNMT3A, is allosterically regulated through ADD-domain autoinhibition and PWWP-domain-dependent oligomerization, is stimulated by DNMT3L and by catalytically inactive isoforms (including Dnmt3b3), cooperates with DNMT1 (but not DNMT3A) for maintenance methylation, binds NEDDylated CUL4A and nucleosome acidic patches to target chromatin, and also functions as a non-catalytic accessory cofactor and direct transcriptional repressor during embryonic development.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"DNMT3B is a de novo DNA methyltransferase that establishes cytosine methylation at centromeric satellite repeats, gene bodies, and active enhancers during embryonic and tissue development [#0, #12]. Genetic ablation in mice blocks de novo methylation and is specifically required for methylation of centromeric minor satellite repeats [#0], and missense and splice mutations in DNMT3B cause ICF syndrome, characterized by pericentromeric satellite hypomethylation [#1]. Structurally, DNMT3B operates by a non-cooperative (processive) catalytic mechanism distinct from DNMT3A, with a catalytic-loop hydrogen bond and a unique +1 flanking-base sensor (Lys777) that confer lower CpG specificity and characteristic flanking-sequence preferences [#15, #19]. Its activity is allosterically gated by an autoinhibitory ADD-MTase interaction and by PWWP-dependent oligomerization, with chromatin reading through ADD-H3K4me0 and PWWP-H3K36me3 binding [#21], and ICF mutations at the FF homo-oligomerization interface impair DNA binding and heterochromatin targeting [#20]. DNMT3B is stimulated by DNMT3L and by catalytically inactive isoforms such as DNMT3B3, which acts as a DNMT3L-like accessory factor that forms a 2:2 complex with DNMT3A2 and preferentially supports DNMT3B2 [#3, #18]; the inactive DNMT3B3 domain docks onto the nucleosome acidic patch to orient the catalytic enzyme toward linker DNA [#16]. Beyond catalysis, DNMT3B functions as a non-catalytic accessory cofactor — catalytically dead DNMT3B rescues most methylation defects and embryonic lethality of Dnmt3b-null embryos — and as a direct transcriptional repressor of genes including Wnt9b [#14]. It cooperates with DNMT1 (but not DNMT3A) for maintenance methylation [#25], and DNMT3B loss destabilizes centromeric R-loops, generating endonuclease-driven breaks and chromosomal instability [#28]. Its expression is post-transcriptionally controlled by miR-148, HuR, Rbm10-dependent splicing, and Akt-coupled protein stability [#5, #6, #26, #27].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Established DNMT3B as a developmentally essential de novo methyltransferase with locus specificity, resolving which DNMT initiates methylation at centromeric repeats and linking it to human disease.\",\n      \"evidence\": \"Knockout mice with bisulfite methylation analysis, plus ICF patient mutation screening with somatic cell fusion complementation\",\n      \"pmids\": [\"10555141\", \"10588719\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define the catalytic mechanism or sequence preferences\", \"Targeting determinants to centromeric satellite not established\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Showed DNMT3B acts together with DNMT1 to maintain genomic methylation and silencing in human cells, distinguishing cooperative maintenance from de novo activity.\",\n      \"evidence\": \"Targeted gene disruption in colorectal cancer cells with methyltransferase assays, bisulfite sequencing, and imprinting/silencing readouts\",\n      \"pmids\": [\"11932749\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether DNMT3A also cooperates with DNMT1 was not resolved here\", \"Molecular basis of DNMT1-DNMT3B cooperation undefined\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Identified DNMT3L as a direct protein partner that stimulates DNMT3B catalysis rather than its DNA targeting, framing accessory-factor regulation of activity.\",\n      \"evidence\": \"In vitro methyltransferase and binding assays with DNMT3L domain deletions\",\n      \"pmids\": [\"15105426\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of stimulation not defined\", \"In vivo relevance of the 1.5-3 fold effect unclear\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Demonstrated that DNMT3A and DNMT3B form a native complex and mutually stimulate activity independent of catalysis, foreshadowing non-catalytic regulatory roles.\",\n      \"evidence\": \"Native complex purification, reciprocal Co-IP, in vitro activity assays with catalytic mutants, and bisulfite sequencing of Oct4/Nanog promoters\",\n      \"pmids\": [\"17938196\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry and structure of the complex not determined\", \"Whether DNMT3A-DNMT3B cooperate in vivo for maintenance not addressed\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Defined post-transcriptional control of DNMT3B by miR-148 acting on the coding region, with isoform-selective escape, explaining differential isoform regulation.\",\n      \"evidence\": \"miRNA overexpression/knockdown and site-directed mutagenesis of the target site with mRNA/protein quantification\",\n      \"pmids\": [\"18367714\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological contexts where miR-148 controls DNMT3B not mapped\", \"Downstream methylation consequences not measured\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Showed mRNA stability control of DNMT3B by HuR couples the enzyme to stress signaling, linking transcript half-life to global methylation.\",\n      \"evidence\": \"Endogenous HuR RNP-IP, biotinylated RNA pulldown, mRNA stability and global methylation assays with cisplatin treatment\",\n      \"pmids\": [\"19270063\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab; signaling pathway driving HuR dissociation incompletely defined\", \"Locus-specific methylation effects not resolved\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Connected DNMT3B to the NEDDylation/cullin machinery, identifying NEDDylated CUL4A as a partner that enhances DNMT3B-dependent methylation and chromatin recruitment.\",\n      \"evidence\": \"Co-IP, in vitro NEDD8 binding, ChIP at a repressed promoter, and Dnmt3b deletion in a cancer cell line\",\n      \"pmids\": [\"20847044\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional role of CUL4A recruitment in normal development unclear\", \"Whether NEDDylation regulates DNMT3B turnover not addressed\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Reported an in vitro 5-hmC dehydroxymethylase activity for DNMT3A/3B dependent on their catalytic sites, raising a possible demethylation-related function.\",\n      \"evidence\": \"In vitro biochemical dehydroxymethylation assay with active-site mutagenesis\",\n      \"pmids\": [\"22898819\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vitro reconstitution not independently replicated in this corpus\", \"Physiological significance in cells/embryos unestablished\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Genetic epistasis in HSCs revealed synergy between Dnmt3a and Dnmt3b and that the predominant adult-HSC Dnmt3b isoform is catalytically inactive yet functionally consequential.\",\n      \"evidence\": \"Conditional single and combined KO mice, HSC transplantation, whole-genome bisulfite sequencing, pathway analysis\",\n      \"pmids\": [\"25130491\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of inactive-isoform contribution not biochemically defined here\", \"How combined loss activates beta-catenin signaling unresolved\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Distinguished DNMT3B's catalytic mechanism as non-cooperative/processive, unlike DNMT3A, and showed the dimer interface plays a limited regulatory role.\",\n      \"evidence\": \"In vitro methylation kinetics, R829H mutagenesis (analogous to DNMT3A R882H), and buffer acidification experiments\",\n      \"pmids\": [\"27768276\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of processivity not yet visualized\", \"Whether processivity shapes genomic targeting unaddressed\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Defined non-catalytic accessory roles of inactive DNMT3B isoforms in stimulating gene-body methylation and recruiting DNMT3A, extending the DNMT3L-like paradigm to somatic cells, and connected DNMT3B to enhancer methylation, REST-directed non-CpG methylation, and melanoma suppression via miR-196b/RICTOR/mTORC2.\",\n      \"evidence\": \"Re-methylation assays after 5-aza with catalytic-mutant isoforms; ChIP-seq/RRBS at enhancers in epidermal stem cells; Dnmt3b KO hearts with CpG/non-CpG bisulfite and REST ChIP; conditional KO melanoma model with target validation\",\n      \"pmids\": [\"27121154\", \"27476967\", \"27956497\", \"26923591\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Recruitment specificity of inactive isoforms across tissues not unified\", \"Direct versus indirect transcriptional effects partly inferred\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Established Rbm10-mediated alternative splicing as a controller of the active/inactive DNMT3B isoform ratio with consequences for NF-kB-responsive promoter methylation and inflammation.\",\n      \"evidence\": \"Rbm10 KO mice and cells, isoform RT-PCR, bisulfite sequencing of NF-kB targets, NF-kB ChIP, Dnmt3b2 overexpression\",\n      \"pmids\": [\"29309623\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Generalizability beyond the inflammatory loci tested unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Showed DNMT3B acts as a direct transcriptional repressor of Rbpjk to control Notch signaling during skeletal progenitor differentiation and fracture repair.\",\n      \"evidence\": \"Conditional KO mice (Prx1-Cre), ChIP-defined Rbpjk binding, luciferase reporters, differentiation assays, pharmacologic Rbpjk rescue\",\n      \"pmids\": [\"32051335\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether repression requires catalysis at Rbpjk not separated\", \"Cofactors mediating repression unidentified\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Definitively established a catalysis-independent function: a catalytically dead Dnmt3b rescues most methylation, transcriptome changes, and embryonic lethality, and directly represses Wnt9b.\",\n      \"evidence\": \"Catalytically inactive Dnmt3b knock-in mice with genome-wide methylation and transcriptomics; Akt-DNMT3B interaction Co-IP defining stability control via mahanine\",\n      \"pmids\": [\"31558711\", \"24001151\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular partners executing the accessory function not fully defined\", \"How Akt regulates DNMT3B ubiquitination mechanistically unresolved\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Structural and enzymological work explained DNMT3B's distinct CpG specificity and flanking-base sensing, and visualized accessory DNMT3B3 docking on the nucleosome acidic patch to position the active enzyme; rescue in triple-KO mESCs showed DNMT3B3 rivals DNMT3L and preferentially supports DNMT3B2.\",\n      \"evidence\": \"Crystal structures with enzymology and mutagenesis; randomized-flank in vitro methylation with interface-residue mutagenesis; cryo-EM of DNMT3A2-DNMT3B3-nucleosome; in vitro stoichiometry plus triple-KO mESC rescue and genome-wide methylation\",\n      \"pmids\": [\"32620778\", \"33105482\", \"32968275\", \"33004415\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How nucleosomal DNA is repositioned for methylation not directly observed\", \"In vivo balance of homo- versus accessory complexes incompletely quantified\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Cryo-EM of the DNMT3B homo-oligomer defined a distinct FF interface and showed ICF mutations there impair DNA binding and heterochromatin targeting; parallel work linked DNMT3B loss to centromeric R-loop instability.\",\n      \"evidence\": \"Cryo-EM homo-oligomer structure with DNA-binding and ChIP/methylation assays using ICF mutants; KO/ICF cells with DNA-damage ChIP-seq, R-loop imaging, and endonuclease inhibition\",\n      \"pmids\": [\"35869095\", \"35688824\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How the homo-oligomer interconverts with heterotetramers in cells unresolved\", \"R-loop instability mechanism downstream of XPG/XPF cleavage not fully mapped\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Defined the allosteric architecture of DNMT3B — ADD-mediated autoinhibition and PWWP-driven tetramer assembly coupled to substrate-site folding — and showed a placenta-specific requirement underlying embryonic lethality.\",\n      \"evidence\": \"Cryo-EM under multiple oligomerization states with biochemistry; Sox2-Cre embryo-restricted deletion versus global KO with whole-genome bisulfite, transcriptomics, and placental histology\",\n      \"pmids\": [\"37941146\", \"36690623\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How histone-mark binding switches activity in chromatin context not fully integrated\", \"Trophoblast-specific targeting determinants undefined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Showed DNMT3B specifically (not DNMT3A) cooperates with DNMT1 for maintenance methylation, with demethylation reversibly remodeling heterochromatin and genome compartmentalization.\",\n      \"evidence\": \"Inducible DNMT1 degradation (dTAG), whole-genome bisulfite sequencing, Hi-C, lamina-associated domain analysis, live imaging\",\n      \"pmids\": [\"38376465\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct physical basis of DNMT1-DNMT3B cooperation not shown\", \"Single lab\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How DNMT3B's oligomerization states, accessory-isoform complexes, and histone-mark reading are dynamically coordinated to select specific genomic loci in vivo remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model linking chromatin context to oligomeric state in cells\", \"Recruitment determinants at centromeres versus enhancers versus gene bodies not reconciled\", \"In vivo significance of in vitro 5-hmC dehydroxymethylase activity unestablished\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140097\", \"supporting_discovery_ids\": [0, 15, 17, 19]},\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [20, 21, 9]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [14, 22, 13]},\n      {\"term_id\": \"GO:0042393\", \"supporting_discovery_ids\": [21]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [11, 18, 14]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [12, 13, 20]},\n      {\"term_id\": \"GO:0000228\", \"supporting_discovery_ids\": [0, 16, 28]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [12, 20, 25]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [14, 22, 13]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [0, 24, 23]},\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [28]}\n    ],\n    \"complexes\": [\n      \"DNMT3A-DNMT3B complex\",\n      \"DNMT3A2-DNMT3B3-nucleosome ternary complex\",\n      \"DNMT3B-DNMT3L heterotetramer\",\n      \"DNMT3B methyltransferase homo-oligomer\"\n    ],\n    \"partners\": [\n      \"DNMT3A\",\n      \"DNMT3L\",\n      \"DNMT1\",\n      \"DNMT3B3\",\n      \"CUL4A\",\n      \"NEDD8\",\n      \"HuR\",\n      \"AKT\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}