{"gene":"SUV39H1","run_date":"2026-06-10T10:51:54","timeline":{"discoveries":[{"year":2001,"finding":"Murine Suv39h histone methyltransferases govern H3K9 trimethylation specifically at pericentric heterochromatin; Suv39h-deficient mice display impaired viability, chromosomal instabilities, increased tumor risk, and perturbed chromosome interactions during male meiosis, establishing a crucial role for pericentric H3-K9 methylation in protecting genome stability.","method":"Suv39h double-knockout mice; immunofluorescence; chromosome analysis","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic loss-of-function in mice with multiple defined cellular and organismal phenotypes, replicated across multiple assays","pmids":["11701123"],"is_preprint":false},{"year":2000,"finding":"SUV39H1 transiently accumulates at centromeric positions during prometaphase and dissociates at the meta-to-anaphase transition; overexpression of full-length SUV39H1 induces severe mitotic defects and chromosome segregation errors and disperses the focal G2-specific distribution of phosphorylated histone H3 at serine 10; these properties depend on the C-terminal SET domain, while the N-terminal chromo domain plus first 44 amino acids direct specific accumulation at heterochromatin. The M31 (HP1β) interaction surface maps to the first 44 N-terminal amino acids.","method":"Structure-function analysis with deletion/truncation mutants in transfected cells; immunofluorescence; mitotic progression assays","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — systematic structure-function analysis with multiple defined mutants and multiple orthogonal cellular readouts","pmids":["10779362"],"is_preprint":false},{"year":2000,"finding":"SUV39H1 selectively associates with the active centromere of a dicentric chromosome and with neocentromeres during prometaphase, and is a phosphoprotein; two additional phosphorylated isoforms appear specifically in mitotic extracts at serine and to a lesser degree threonine residues, while steady-state protein levels remain constant during the cell cycle.","method":"Cell-cycle fractionation; immunofluorescence on dicentric/neocentromere chromosomes; phosphopeptide analysis","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization experiments and biochemical detection of phosphorylation, single lab, multiple methods","pmids":["10671371"],"is_preprint":false},{"year":2003,"finding":"Suv39h-mediated H3K9 trimethylation at pericentric heterochromatin is required to direct Dnmt3b-dependent DNA methylation to major satellite repeats; in Suv39h double-null ES cells, Dnmt3b fails to localize to heterochromatic foci and displays altered DNA methylation at pericentric satellite repeats. Conversely, H3K9 trimethylation at pericentric heterochromatin is not impaired in Dnmt-deficient ES cells. Physical interaction between Dnmt3b and HP1α is also demonstrated.","method":"Suv39h double-null mouse ES cells; immunofluorescence; bisulfite sequencing; co-immunoprecipitation","journal":"Current biology : CB","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis in null cells, multiple orthogonal methods, clearly ordered pathway","pmids":["12867029"],"is_preprint":false},{"year":2003,"finding":"SUV39H1 physically interacts with Dnmt3a (via Dnmt3a's PHD-like motif), with Dnmt1, and with HP1β both in vitro (GST pulldown) and in vivo (co-IP); SUV39H1 can purify DNA methyltransferase activity from nuclear extracts; HP1β also directly binds Dnmt1 and Dnmt3a, establishing a direct connection between the histone methylation and DNA methylation machineries.","method":"Co-immunoprecipitation (endogenous and transfected); GST pulldown; histone methyltransferase activity assay on nuclear extracts","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — reciprocal co-IP plus in vitro pulldown plus enzymatic assay, single lab, multiple methods","pmids":["12711675"],"is_preprint":false},{"year":2002,"finding":"SUV39H1 physically interacts with HDAC1, HDAC2, and HDAC3 by co-immunoprecipitation; the N-terminal portion of SUV39H1 (not requiring its catalytic SET domain) constitutes a transcriptional repression domain that binds the core HDAC complex (HDAC1, HDAC2, RbAp48, RbAp46); repression of a heterologous promoter by SUV39H1 is dependent on histone deacetylase activity.","method":"Co-immunoprecipitation; reporter gene repression assay; HDAC inhibitor treatment","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP plus functional repression assay, single lab, two methods","pmids":["11788710"],"is_preprint":false},{"year":2003,"finding":"The chromo shadow domain of HP1α directly interacts with the N-terminal 39 amino acid stretch of SUV39H1; a self-interaction (dimerization) of HP1α through its chromo shadow domain is required for this direct binding; a consensus peptide that disrupts chromo shadow domain dimerization also inhibits HP1α–SUV39H1 interaction.","method":"Yeast two-hybrid; GST pulldown; interaction-disrupting peptide; point mutagenesis (IY165/168EE)","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with mutagenesis, single lab","pmids":["12565857"],"is_preprint":false},{"year":2004,"finding":"Suv39h mediates H3K9 methylation at Rb/E2F target promoters specifically in differentiating (but not cycling) cells; siRNA knockdown of Suv39h prevents H3K9 methylation and subsequent repression of S-phase gene promoters in differentiating myoblasts, and Suv39h-depleted myoblasts fail to express muscle differentiation markers.","method":"Chromatin immunoprecipitation; siRNA knockdown; gene expression analysis in cycling vs. differentiating cells","journal":"The EMBO journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP plus RNAi loss-of-function with defined phenotypic readout, single lab","pmids":["14765126"],"is_preprint":false},{"year":2005,"finding":"A substantial population of SUV39H1 is immobile at pericentromeric heterochromatin (FRAP analysis); the SET domain mediates this stable, structural binding to heterochromatin; recruitment of SUV39H1 to heterochromatin is at least partly independent of HP1; HP1 transiently interacts with SUV39H1 at heterochromatin (FRET).","method":"FRAP (fluorescence recovery after photobleaching); FRET; deletion mutant analysis in living cells","journal":"The Journal of cell biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — live-cell imaging with functional domain mapping, single lab, multiple methods","pmids":["16103223"],"is_preprint":false},{"year":2006,"finding":"Suv39h1 interacts with MyoD in proliferating muscle cells and its HMT activity is associated with the MyoD complex on the chromatin regulatory regions of the myogenin gene, correlating with H3K9 methylation; increased Suv39h1 represses MyoD-dependent muscle gene expression in a manner requiring both its HMT activity and its association with MyoD; siRNA-mediated abrogation of Suv39h1 activates muscle gene expression by MyoD.","method":"Co-immunoprecipitation; chromatin immunoprecipitation; overexpression; siRNA knockdown; reporter assays","journal":"The EMBO journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP plus co-IP plus loss-of-function RNAi with defined phenotypic readout, single lab","pmids":["16858404"],"is_preprint":false},{"year":2007,"finding":"SIRT1 directly interacts with SUV39H1, recruits it, and deacetylates SUV39H1 at lysine 266 within its catalytic SET domain; acetylation at K266 inhibits SUV39H1 activity; SIRT1-mediated deacetylation independently contributes to elevated SUV39H1 H3K9me3 methyltransferase activity and increased H3K9me3 levels; loss of SIRT1 greatly reduces SUV39H1-dependent H3K9me3 and impairs HP1 localization.","method":"Co-immunoprecipitation; in vitro deacetylation assay; site-directed mutagenesis (K266); immunofluorescence; SIRT1 knockdown/knockout","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro biochemical assay plus site-directed mutagenesis plus cellular loss-of-function, multiple orthogonal methods","pmids":["18004385"],"is_preprint":false},{"year":2007,"finding":"Suv39H1, HP1γ, and H3K9 trimethylation are reversibly associated with the integrated HIV-1 promoter in a transcription-dependent manner and play a major role in chromatin-mediated repression of HIV-1 gene expression and post-integration latency; knockdown of HP1γ (not SUV39H1 directly) by RNA interference reactivated HIV-1 in multiple cellular models including PBMCs from HIV-1-infected donors.","method":"Chromatin immunoprecipitation; siRNA knockdown; reporter assays; primary cell models","journal":"The EMBO journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP plus RNAi with functional viral reactivation readout, single lab","pmids":["17245432"],"is_preprint":false},{"year":2010,"finding":"A subset of H3K9 methyltransferases — G9a, GLP, SETDB1, and Suv39h1 — co-exist in the same megacomplex; in Suv39h or G9a null cells, the remaining HKMTs are destabilized at the protein level, indicating interdependence; all four HKMTs are recruited to major satellite repeats and to multiple G9a target genes, where they functionally cooperate.","method":"Co-immunoprecipitation; protein stability in null cells; chromatin immunoprecipitation","journal":"Molecular cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP plus genetic epistasis (null cells) plus ChIP, single lab","pmids":["20129054"],"is_preprint":false},{"year":2011,"finding":"SirT1 controls global levels of Suv39h1 by increasing its protein half-life through inhibition of MDM2-dependent polyubiquitination of Suv39h1 at lysine 87; SirT1 upregulation (e.g., under calorie restriction) increases Suv39h1 protein levels in vivo; this mechanism regulates Suv39h1 turnover at constitutive heterochromatin and ensures genome integrity.","method":"Protein stability assays; ubiquitination assays; site-directed mutagenesis (K87); co-immunoprecipitation; in vivo calorie restriction model","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — biochemical ubiquitination assay plus mutagenesis plus in vivo model, multiple orthogonal methods","pmids":["21504832"],"is_preprint":false},{"year":2012,"finding":"Snail interacts with Suv39H1 via the SNAG domain of Snail and the SET domain of Suv39H1; Snail recruits Suv39H1 to the E-cadherin promoter, leading to H3K9me3 and DNA methylation-based transcriptional repression; knockdown of Suv39H1 restores E-cadherin expression and inhibits cell migration, invasion, and metastasis of basal-like breast cancer cells.","method":"Co-immunoprecipitation; chromatin immunoprecipitation; siRNA knockdown; domain mapping; cell migration/invasion assays; in vivo metastasis assay","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP with domain mapping plus ChIP plus functional knockdown assays, single lab","pmids":["22562246"],"is_preprint":false},{"year":2013,"finding":"SET7/9 interacts with SUV39H1 (via the chromodomain-containing region of SUV39H1) in response to adriamycin treatment; SET7/9 methylates SUV39H1 at lysines 105 and 123 (confirmed by mass spectrometry and specific antibodies); this methylation dramatically downregulates SUV39H1 methyltransferase activity, reduces H3K9me3 at heterochromatin, causes heterochromatin relaxation (increased satellite repeat transcription, increased MNase sensitivity), genome instability, and inhibits cell proliferation.","method":"Co-immunoprecipitation; GST pulldown; mass spectrometry; western blot with methylation-specific antibodies; in vitro methyltransferase assay; MNase sensitivity assay; immunofluorescence","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro enzymatic assay plus MS identification of modification sites plus multiple cellular functional assays, single lab with multiple orthogonal methods","pmids":["23509280"],"is_preprint":false},{"year":2013,"finding":"A-type lamins interact with SUV39H1; prelamin A/progerin exhibits enhanced binding capacity to SUV39H1 compared to mature lamin A, protecting SUV39H1 from proteasomal degradation and consequently increasing H3K9me3 levels; depletion of Suv39h1 reduces H3K9me3, restores DNA repair capacity, delays senescence in progeroid cells, and extends lifespan of Zmpste24−/− mice by ~60%.","method":"Co-immunoprecipitation; protein stability assays; siRNA/genetic Suv39h1 depletion; DNA repair assays; mouse lifespan analysis","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — co-IP plus protein stability plus genetic KO rescue with multiple phenotypic readouts including in vivo lifespan","pmids":["23695662"],"is_preprint":false},{"year":2013,"finding":"CRL4B (containing CUL4B) associates with SUV39H1, HP1, and DNMT3A; CRL4B, through catalyzing H2AK119 monoubiquitination, facilitates SUV39H1-dependent H3K9 trimethylation and DNA methylation; depletion of CUL4B results in loss of H3K9me3 and DNA methylation at target gene promoters.","method":"Co-immunoprecipitation; chromatin immunoprecipitation; siRNA knockdown; ubiquitination assays","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP plus ChIP plus loss-of-function, single lab","pmids":["24292684"],"is_preprint":false},{"year":2014,"finding":"CDK2 directly phosphorylates Suv39H1 at Ser391; phosphorylation levels oscillate during the cell cycle, peaking at S phase; CDK2-mediated phosphorylation at Ser391 causes preferential dissociation of Suv39H1 from chromatin, enhances occupancy of JMJD2A histone demethylase on heterochromatin, alters inactive histone marks, and phospho-mimic Suv39H1 induces early replication of heterochromatin.","method":"In vitro kinase assay; phospho-specific antibodies; cell cycle synchronization; chromatin fractionation; overexpression of phospho-mimic/phospho-defective mutants; replication timing assay","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro kinase assay plus mutagenesis plus cell-cycle-synchronized chromatin fractionation, single lab, multiple methods","pmids":["24728993"],"is_preprint":false},{"year":2014,"finding":"Suv39h1 enhances AP-2α-mediated transcriptional repression of C/EBPα during adipogenesis; Suv39h1 interacts with AP-2α and with G9a; G9a mediates H3K9me2 at the C/EBPα promoter, providing the substrate for Suv39h1-mediated H3K9me3; knockdown of Suv39h1 increases C/EBPα expression and promotes adipogenesis, while Suv39h1 overexpression impairs adipocyte differentiation.","method":"Co-immunoprecipitation; chromatin immunoprecipitation; siRNA knockdown; overexpression; differentiation assays","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP plus ChIP with sequential H3K9me2/me3 pathway dissection, single lab","pmids":["24732798"],"is_preprint":false},{"year":2014,"finding":"Suv39h-dependent H3K9me3 selectively accumulates at intact (full-length) LINE elements and ERVs (~8,150 intact LINEs/ERVs) covering ~5% of the ES cell epigenome; transcriptional repression of intact LINEs and ERVs is differentially regulated by Suv39h and other chromatin modifiers in ES cells but governed by DNA methylation in committed cells.","method":"Genome-wide ChIP sequencing in Suv39h double-null vs. wild-type mouse ES cells; bioinformatic repeat subfamily analysis","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — genome-wide ChIP-seq in genetic null cells with rigorous bioinformatic analysis","pmids":["24981170"],"is_preprint":false},{"year":2016,"finding":"Suv39h1 operates through a two-step allosteric activation switch: (1) H3K9me3 recognition by its chromodomain anchors the enzyme to chromatin, (2) this anchoring allosterically promotes methyltransferase activity, enabling positive feedback spreading of H3K9me2/3 over heterochromatic regions; this mechanism was confirmed in cells using chromodomain mutants.","method":"Semi-synthetic 'designer chromatin' reconstitution with chemically defined nucleosomal substrates; in vitro methyltransferase assay; mutagenesis of chromodomain; cellular confirmation","journal":"Nature chemical biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — fully reconstituted in vitro system with designer chromatin plus mutagenesis plus cellular validation","pmids":["26807716"],"is_preprint":false},{"year":2016,"finding":"Suv39h1 promotes HP1α sumoylation both in vitro and in vivo through a region (aa1-167) distinct from its catalytic KMT domain that mediates binding to Ubc9; tethering this 1-167 domain to pericentric heterochromatin accelerates de novo targeting of HP1α to these domains; mutants unable to bind Ubc9 lack this activity.","method":"In vitro sumoylation assay; co-immunoprecipitation; tethering assay; mutagenesis","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 1–2 / Moderate — in vitro sumoylation assay plus cellular tethering experiment plus mutagenesis, single lab","pmids":["27426629"],"is_preprint":false},{"year":2017,"finding":"Chromatin-associated RNA (encoded partly by α-satellite sequences, retained in cis) contributes to stable association of SUV39H1 with constitutive heterochromatin; purified SUV39H1 directly binds nucleic acids through its chromodomain; nucleic acid-binding mutants of SUV39H1 and RNase treatment or RNA polymerase inhibition destabilize SUV39H1 association with chromatin in mitotic and interphase cells and cause heterochromatin function defects.","method":"In vitro nucleic acid binding assay (purified protein); chromodomain mutagenesis; RNase treatment of cells; RNA polymerase inhibition; live-cell imaging; chromatin fractionation","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro binding reconstitution plus mutagenesis plus multiple cellular perturbations, multiple orthogonal methods","pmids":["28760200"],"is_preprint":false},{"year":2017,"finding":"Suv39h2 (paralog) contains an N-terminal basic domain that facilitates retention at mitotic chromatin and provides additional affinity for major satellite repeat RNA; Suv39h1 (and Suv39h2) exclusively associate with poly-nucleosomes purified from mouse ES cells; this association is attenuated by RNaseH and entirely lost by RNaseA, indicating RNA:DNA hybrid-dependent and RNA-dependent chromatin association respectively; major satellite repeat transcripts have secondary structures favoring RNA:DNA hybrid formation.","method":"Native nucleosome purification; RNase treatment; EMSA; structural analysis of RNA","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1 / Moderate — biochemical reconstitution with nucleosomes plus enzymatic dissection, single lab, multiple methods","pmids":["28760199"],"is_preprint":false},{"year":2017,"finding":"Suv39h1's chromodomain binds nucleic acids (higher affinity for RNA than DNA) independently of H3K9me3 recognition; Suv39h1 binds major satellite RNAs in vivo; knockdown of major satellite RNAs reduces Suv39h1 retention at pericentromere; both nucleic acid-binding and H3K9me-binding activities of Suv39h1's chromodomain are required for pericentric heterochromatin assembly.","method":"EMSA with purified chromodomain; RNA immunoprecipitation in vivo; RNA knockdown; chromodomain mutagenesis; immunofluorescence","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro binding assay plus mutagenesis plus in vivo RNA-IP and RNA knockdown, multiple orthogonal methods","pmids":["28760201"],"is_preprint":false},{"year":2017,"finding":"SUV39H cooperates with HP1γ to catalyze H3K9 trimethylation on the SIRT1 promoter, thereby repressing SIRT1 transcription in cardiomyocytes under ischemic/oxidative stress; SUV39H knockout mice are protected from myocardial infarction, and SUV39H inhibition attenuates cardiac injury following MI; SUV39H augments intracellular ROS levels in a SIRT1-dependent manner.","method":"Chromatin immunoprecipitation; SUV39H knockout mice; pharmacological inhibition (chaetocin); gene expression analysis; cardiac function measurement","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO plus ChIP plus pharmacological inhibition with defined molecular mechanism, single lab","pmids":["28361889"],"is_preprint":false},{"year":2017,"finding":"SUV39H1 substrate specificity requires recognition of H3 residues between K4 and G12, with highly specific readout of R8; SUV39H1 methylates non-histone substrates including RAG2, SET8, and DOT1L in cells; methylation of SET8 allosterically stimulates its H4K20 monomethylation activity, connecting SUV39H1 to increased H4K20me3; methylation of RAG2 alters its subnuclear localization.","method":"Peptide array substrate specificity profiling; in vitro methyltransferase assay at protein level; cellular methylation confirmation; functional activity assay for SET8","journal":"ACS chemical biology","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — in vitro enzymatic assay plus cellular validation, single lab, multiple substrates","pmids":["28169523"],"is_preprint":false},{"year":2017,"finding":"SUV39H1 methylates the mycobacterial histone-like protein HupB; this trimethylation reduces the cell adhesion capability of mycobacteria and reduces mycobacterial survival inside host cells and biofilm formation; SUV39H1 associates with mycobacterial bacilli during infection.","method":"In vitro methyltransferase assay; co-immunoprecipitation; bacterial adhesion assays; intracellular survival assays; mouse infection model","journal":"The EMBO journal","confidence":"Medium","confidence_rationale":"Tier 1–2 / Moderate — in vitro enzymatic assay plus cellular and in vivo functional assays, single lab","pmids":["29170282"],"is_preprint":false},{"year":2018,"finding":"Automethylation of specific lysines in an internal loop of Clr4 (the S. pombe ortholog of SUV39H) inhibits catalytic activity by blocking the H3K9 substrate-binding pocket; automethylation promotes a conformational switch that enhances H3K9me activity; mutations disrupting this regulation lead to aberrant H3K9me and epigenetic instability; a corresponding lysine in human SUV39H2 is also automethylated, suggesting conserved mechanism.","method":"X-ray crystallography; biochemical methyltransferase assays; mutagenesis; in vivo heterochromatin analysis in S. pombe","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure plus biochemical reconstitution plus mutagenesis plus in vivo validation, multiple orthogonal methods","pmids":["30051891"],"is_preprint":false},{"year":2018,"finding":"SirT6 binds to Suv39h1 and induces monoubiquitination of conserved cysteines in the PRE-SET domain of Suv39h1; following NF-κB signaling activation, Suv39h1 is released from the IκBα locus; SirT6-mediated cysteine monoubiquitination of Suv39h1 attenuates NF-κB pathway activity through IκBα upregulation.","method":"Co-immunoprecipitation; ubiquitination assay; chromatin immunoprecipitation; site-directed mutagenesis; NF-κB reporter assays","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP plus ChIP plus ubiquitination assay with mutagenesis, single lab","pmids":["29317652"],"is_preprint":false},{"year":2018,"finding":"CRL4-DCAF13 E3 ubiquitin ligase targets SUV39H1 for polyubiquitination and proteasomal degradation; Dcaf13 knockout embryos are arrested at the 8–16 cell stage with high levels of H3K9me3; DCAF13-mediated SUV39H1 degradation facilitates H3K9me3 removal and zygotic gene expression during preimplantation development.","method":"Co-immunoprecipitation; ubiquitination assays; Dcaf13 knockout mice; embryo arrest phenotype; immunofluorescence","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with defined developmental arrest phenotype plus biochemical ubiquitination assay, multiple methods","pmids":["30111536"],"is_preprint":false},{"year":2012,"finding":"SUV39H1 orchestrates temporal dynamics of H3K9 methylation at the centromere during chromosome segregation; inhibition of SUV39H1 methylation dynamics perturbs chromosome congression, causes a brief increase in Aurora B kinase activity, enrichment of MCAK at centromeres, kinetochore-microtubule destabilization, reduced tension across sister kinetochores, and chromosome misalignment.","method":"FRET-based methylation sensors targeted to centromeres in living HeLa cells; immunofluorescence; pharmacological SUV39H1 inhibition (chaetocin)","journal":"Journal of molecular cell biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — live-cell FRET sensors plus pharmacological perturbation, single lab","pmids":["22831836"],"is_preprint":false},{"year":2013,"finding":"N-terminally truncated Suv39h1 (ΔN, HP1-binding defective) introduced into Suv39h-deficient ES cells recovers pericentric H3K9me3 and Dnmt3a/3b accumulation and DNA methylation at pericentromeres, but only marginally restores HP1 accumulation; Suv39h-HP1 direct binding is dispensable for pericentric H3K9me3 and DNA methylation but is required for full HP1 recruitment and complete heterochromatin features (ATRX association, H4K20me3).","method":"Reconstitution of truncation mutants in Suv39h-null ES cells; immunofluorescence; ChIP; bisulfite sequencing","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic reconstitution with defined mutants in null cells, multiple readouts, single lab","pmids":["23836914"],"is_preprint":false},{"year":2017,"finding":"HP1α and HP1γ (but not HP1β) preferentially interact in vivo with Suv39h1 and regulate its dynamics and stability at heterochromatin by inhibiting MDM2-dependent Suv39h1-K87 polyubiquitination; reciprocally, Suv39h1 increases HP1α stability; loss of HP1α and γ inhibits stress-induced upregulation of Suv39h1 and H3K9me3; Suv39h1 deficiency abrogates stress-dependent upregulation of HP1α and γ.","method":"Co-immunoprecipitation; FRAP; protein stability assays; ubiquitination assays; isoform-specific knockdown","journal":"Epigenetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple co-IPs plus protein stability assays plus FRAP, single lab","pmids":["28059589"],"is_preprint":false},{"year":2024,"finding":"H3K18ub (catalyzed by UHRF1) enhances SUV39H1/H2 methyltransferase activity; disrupting H3K18ub-dependent SUV39H1/H2 activity prevents H3K9me3 accumulation at CpG island promoters following DNMT1 inhibition and enhances transcriptional activating and antiproliferative effects of DNMT1 inhibition.","method":"Genome-wide ChIP-seq; in vitro methyltransferase activity assay with H3K18ub nucleosomes; genetic disruption of UHRF1; colon cancer cell models","journal":"Molecular cell","confidence":"Medium","confidence_rationale":"Tier 1–2 / Moderate — in vitro enzymatic assay plus genome-wide ChIP-seq plus genetic perturbation, single lab","pmids":["39631394"],"is_preprint":false},{"year":2024,"finding":"Genetic disruption of SUV39H1 in CAR T cells enhances early expansion, long-term persistence, and antitumor efficacy in leukemia and prostate cancer models; SUV39H1-edited CAR T cells show improved memory transcription factor accessibility, reduced inhibitory receptor expression, and reduced exhaustion upon multiple tumor rechallenges.","method":"Genetic CRISPR editing of SUV39H1 in human CAR T cells; scRNA-seq; scATAC-seq; in vivo tumor rechallenge models","journal":"Cancer discovery","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic loss-of-function with scRNA-seq/scATAC-seq profiling plus in vivo tumor models, single lab","pmids":["37934007"],"is_preprint":false}],"current_model":"SUV39H1 (KMT1A) is an H3K9-specific histone methyltransferase whose SET domain catalyzes di- and trimethylation of H3K9 to establish constitutive and facultative heterochromatin; its activity is regulated by multiple PTMs (SIRT1-mediated deacetylation at K266 activates it, SET7/9-mediated methylation at K105/K123 inhibits it, CDK2-mediated phosphorylation at S391 releases it from chromatin, and MDM2-dependent polyubiquitination at K87 targets it for degradation); it is stably tethered to pericentric heterochromatin through its SET domain and through chromodomain-mediated binding of both H3K9me3 and chromatin-associated RNA (including major satellite/α-satellite transcripts); it interacts directly with HP1 proteins (via its N-terminal 39 residues), HDACs, DNMT3a/Dnmt3b, and numerous transcription factors (Rb/E2F, Snail, MyoD, RUNX1, EVI1, CIITA, and others) to repress gene expression; it also methylates non-histone substrates including RAG2, SET8, and DOT1L; its H3K9me3 mark directs Dnmt3b-dependent DNA methylation to pericentric satellite repeats, silences intact LINE retrotransposons in ES cells, and is required for genome stability and faithful chromosome segregation."},"narrative":{"mechanistic_narrative":"SUV39H1 is a SET-domain histone methyltransferase that establishes constitutive heterochromatin by trimethylating histone H3 at lysine 9 (H3K9me3) at pericentric regions, an activity required to protect genome stability and ensure faithful chromosome segregation [PMID:11701123, PMID:10779362]. Its substrate engagement depends on recognition of H3 residues flanking K9, with strict readout of R8 [PMID:28169523]. Stable tethering to heterochromatin is achieved through two complementary modules: the SET domain mediates structural, near-immobile binding to pericentric chromatin, while the chromodomain recognizes both pre-existing H3K9me3 and chromatin-associated RNA, including major satellite/α-satellite transcripts that retain the enzyme in cis [PMID:16103223, PMID:26807716, PMID:28760200, PMID:28760201]. Chromodomain-based H3K9me3 reading also drives a two-step allosteric activation switch, anchoring the enzyme and stimulating catalysis to spread H3K9me2/3 by positive feedback [PMID:26807716]. SUV39H1-deposited H3K9me3 in turn directs Dnmt3b-dependent DNA methylation to pericentric satellite repeats and silences intact LINE/ERV retrotransposons in ES cells, with the histone and DNA methylation machineries physically bridged through direct interactions with DNMT3a, DNMT1, and HP1 proteins [PMID:12867029, PMID:12711675, PMID:24981170]. SUV39H1 functions within a larger H3K9 methyltransferase network (G9a, GLP, SETDB1) whose members are mutually stabilized and co-recruited to satellite repeats [PMID:20129054], and it cooperates with HP1 both by binding via its N-terminal residues and by promoting HP1α sumoylation to seed de novo HP1 targeting [PMID:12565857, PMID:27426629, PMID:23836914]. Beyond bulk heterochromatin, it is recruited by sequence-specific transcription factors—including the Rb/E2F axis in differentiating myoblasts, MyoD, AP-2α, and Snail—to deposit repressive H3K9me3 at defined promoters governing cell differentiation, EMT, and metastasis [PMID:14765126, PMID:16858404, PMID:22562246, PMID:24732798]. Its activity is tightly controlled by post-translational modification: SIRT1-mediated deacetylation at K266 activates the enzyme and stabilizes it by blocking MDM2-dependent K87 polyubiquitination, SET7/9-mediated methylation at K105/K123 inhibits it, CDK2 phosphorylation at S391 releases it from chromatin during S phase, and conserved automethylation autoinhibits catalysis [PMID:18004385, PMID:21504832, PMID:23509280, PMID:24728993, PMID:30051891]. SUV39H1 additionally methylates non-histone substrates such as SET8, RAG2, and DOT1L [PMID:28169523].","teleology":[{"year":2000,"claim":"Established that SUV39H1 dynamically localizes to centromeres during mitosis and that its two ends carry separable functions, framing a model in which an N-terminal targeting region and a C-terminal catalytic domain coordinate heterochromatin function.","evidence":"Cell-cycle fractionation, immunofluorescence on dicentric/neocentromere chromosomes, and structure-function analysis with truncation mutants in transfected cells","pmids":["10779362","10671371"],"confidence":"High","gaps":["Did not establish the enzymatic mark deposited in vivo","Phosphorylation sites and responsible kinases unmapped"]},{"year":2001,"claim":"Demonstrated genetically that Suv39h enzymes deposit pericentric H3K9 trimethylation and that this mark is essential for genome stability, defining the core biological role.","evidence":"Suv39h double-knockout mice with chromosome instability, tumor risk, and meiotic defects","pmids":["11701123"],"confidence":"High","gaps":["Mechanism of recruitment to pericentric chromatin not resolved","Downstream effectors of instability undefined"]},{"year":2003,"claim":"Showed that SUV39H1-dependent H3K9me3 acts upstream of DNA methylation by recruiting Dnmt3b, and physically connected the histone and DNA methylation machineries via HP1 and DNMT interactions.","evidence":"Genetic epistasis in Suv39h-null ES cells, bisulfite sequencing, co-IP and GST pulldown with Dnmt3a/Dnmt1/HP1β","pmids":["12867029","12711675"],"confidence":"High","gaps":["Stoichiometry and ordering of the histone-DNA methyltransferase complex unresolved","Whether interactions occur simultaneously in one complex untested"]},{"year":2002,"claim":"Linked SUV39H1 to deacetylase-dependent transcriptional repression, identifying an N-terminal repression domain functioning independently of catalysis.","evidence":"Co-IP with HDAC1/2/3 and reporter repression assays sensitive to HDAC inhibition","pmids":["11788710"],"confidence":"Medium","gaps":["Single lab, two methods","Genomic targets of the HDAC-coupled repression not mapped"]},{"year":2004,"claim":"Defined a context-specific recruitment mode in which Suv39h methylates Rb/E2F target promoters selectively in differentiating cells, coupling heterochromatin machinery to cell-fate decisions.","evidence":"ChIP plus siRNA knockdown with differentiation readouts in myoblasts","pmids":["14765126"],"confidence":"Medium","gaps":["Direct recruitment factor at these promoters not identified here","Single lab"]},{"year":2005,"claim":"Resolved the basis of stable heterochromatin tethering, showing the SET domain confers immobile structural binding largely independent of HP1.","evidence":"FRAP and FRET with deletion mutants in living cells","pmids":["16103223"],"confidence":"Medium","gaps":["Molecular partner mediating SET-dependent anchoring not identified","Transient versus stable HP1 contributions only qualitatively defined"]},{"year":2006,"claim":"Extended factor-directed recruitment by showing Suv39h1 binds MyoD and represses muscle gene expression through HMT activity on target chromatin.","evidence":"Co-IP, ChIP, overexpression and siRNA with reporter and differentiation assays","pmids":["16858404"],"confidence":"Medium","gaps":["Single lab","Interplay with the Rb/E2F differentiation pathway not integrated"]},{"year":2007,"claim":"Identified SIRT1 deacetylation at K266 as a direct activating switch for SUV39H1 catalysis, establishing the first PTM control of enzyme activity.","evidence":"Co-IP, in vitro deacetylation, K266 mutagenesis, and SIRT1 loss-of-function","pmids":["18004385"],"confidence":"High","gaps":["Acetyltransferase responsible for K266 acetylation not identified","Quantitative contribution to global H3K9me3 unclear"]},{"year":2007,"claim":"Implicated the SUV39H1/HP1γ/H3K9me3 axis in chromatin-mediated silencing of integrated HIV-1, extending heterochromatin function to viral latency.","evidence":"ChIP, siRNA, and reporter assays in cellular and primary HIV-1 models","pmids":["17245432"],"confidence":"Medium","gaps":["Direct SUV39H1 knockdown reactivation not demonstrated","Single lab"]},{"year":2010,"claim":"Placed SUV39H1 within a co-dependent megacomplex of H3K9 methyltransferases that are mutually stabilized and co-recruited to satellite and gene targets.","evidence":"Co-IP, protein stability in null cells, and ChIP","pmids":["20129054"],"confidence":"Medium","gaps":["Architecture and direct contacts within the megacomplex unresolved","Single lab"]},{"year":2011,"claim":"Showed SIRT1 controls SUV39H1 abundance by blocking MDM2-dependent K87 polyubiquitination, linking enzyme stability to nutrient state.","evidence":"Ubiquitination and stability assays, K87 mutagenesis, and an in vivo calorie restriction model","pmids":["21504832"],"confidence":"High","gaps":["How SIRT1 inhibits MDM2 toward this substrate not detailed","Other E3 contributions not excluded"]},{"year":2012,"claim":"Demonstrated that SUV39H1 methylation dynamics at the centromere are required for proper kinetochore-microtubule attachment and chromosome congression, mechanistically connecting H3K9 methylation to error-free segregation.","evidence":"Centromere-targeted FRET methylation sensors and chaetocin inhibition in living HeLa cells","pmids":["22831836"],"confidence":"Medium","gaps":["Pharmacological inhibitor specificity limits attribution","Link to Aurora B/MCAK pathway correlative"]},{"year":2012,"claim":"Identified Snail as a recruiter of SUV39H1 to the E-cadherin promoter, defining an EMT/metastasis-promoting repression mechanism via SET-SNAG domain interaction.","evidence":"Co-IP with domain mapping, ChIP, knockdown, and in vivo metastasis assays in breast cancer cells","pmids":["22562246"],"confidence":"Medium","gaps":["Single lab","Generality across other EMT transcription factors untested here"]},{"year":2013,"claim":"Discovered SET7/9-mediated methylation of SUV39H1 at K105/K123 as an inhibitory PTM that relaxes heterochromatin under DNA damage, adding a counterbalancing control to SIRT1 activation.","evidence":"Co-IP, mass spectrometry, methylation-specific antibodies, in vitro MTase and MNase sensitivity assays","pmids":["23509280"],"confidence":"High","gaps":["Physiological signals beyond adriamycin not defined","Crosstalk with K266 acetylation not integrated"]},{"year":2013,"claim":"Showed that A-type lamins (and progerin) stabilize SUV39H1, and that Suv39h1 depletion delays senescence and extends lifespan in progeroid mice, tying heterochromatin maintenance to aging.","evidence":"Co-IP, stability assays, genetic depletion with DNA repair, senescence and Zmpste24-/- lifespan readouts","pmids":["23695662"],"confidence":"High","gaps":["Mechanism by which lamin binding blocks degradation not detailed","Relationship to MDM2/CRL4 pathways unresolved"]},{"year":2013,"claim":"Established CRL4B/H2AK119ub as an upstream facilitator of SUV39H1-dependent H3K9me3 and DNA methylation, adding a ubiquitin-dependent chromatin crosstalk layer.","evidence":"Co-IP with SUV39H1/HP1/DNMT3A, ChIP, knockdown, and ubiquitination assays","pmids":["24292684"],"confidence":"Medium","gaps":["Direct versus indirect facilitation not separated","Single lab"]},{"year":2013,"claim":"Dissected the HP1-binding contribution by showing direct Suv39h-HP1 binding is dispensable for pericentric H3K9me3/DNA methylation but needed for full HP1 recruitment and complete heterochromatin features.","evidence":"Reconstitution of ΔN truncation mutants in Suv39h-null ES cells with IF, ChIP and bisulfite sequencing","pmids":["23836914"],"confidence":"Medium","gaps":["Alternative HP1-independent targeting determinant not identified here","Single lab"]},{"year":2014,"claim":"Identified CDK2 phosphorylation at S391 as a cell-cycle switch that evicts Suv39h1 from chromatin in S phase, allowing demethylase access and altered replication timing.","evidence":"In vitro kinase assay, phospho-specific antibodies, synchronized chromatin fractionation, and phospho-mimic mutants","pmids":["24728993"],"confidence":"High","gaps":["Phosphatase reversing S391 not identified","Coordination with other PTMs across the cycle unmapped"]},{"year":2014,"claim":"Mapped the Suv39h-dependent H3K9me3 landscape genome-wide, showing selective silencing of intact LINE/ERV retrotransposons in ES cells.","evidence":"Genome-wide ChIP-seq in Suv39h double-null versus wild-type ES cells with repeat subfamily analysis","pmids":["24981170"],"confidence":"High","gaps":["Determinants of selectivity for intact elements unresolved","Handoff to DNA methylation in committed cells only inferred"]},{"year":2014,"claim":"Extended factor-directed repression to adipogenesis, showing Suv39h1 cooperates with AP-2α and G9a in a sequential H3K9me2-to-me3 pathway at the C/EBPα promoter.","evidence":"Co-IP, ChIP, knockdown and overexpression with differentiation assays","pmids":["24732798"],"confidence":"Medium","gaps":["Single lab","Ordering of AP-2α versus G9a recruitment correlative"]},{"year":2016,"claim":"Defined the two-step allosteric activation mechanism whereby chromodomain reading of H3K9me3 anchors the enzyme and stimulates catalysis to drive feedback spreading of the mark.","evidence":"Semi-synthetic designer chromatin reconstitution, in vitro MTase assays, chromodomain mutagenesis, cellular validation","pmids":["26807716"],"confidence":"High","gaps":["How spreading is bounded at heterochromatin borders unresolved","Integration with RNA-binding by the same domain not addressed here"]},{"year":2016,"claim":"Revealed a catalysis-independent function in which Suv39h1 binds Ubc9 to promote HP1α sumoylation and seed de novo HP1 targeting.","evidence":"In vitro sumoylation, co-IP, heterochromatin tethering, and Ubc9-binding mutants","pmids":["27426629"],"confidence":"Medium","gaps":["Single lab","Relative contribution versus H3K9me3-driven HP1 recruitment unclear"]},{"year":2017,"claim":"Established that chromatin-associated RNA, including α-satellite/major satellite transcripts, binds the chromodomain to retain SUV39H1 at heterochromatin, defining an RNA-dependent tethering mechanism distinct from H3K9me3 reading.","evidence":"In vitro nucleic acid binding, chromodomain mutagenesis, RNase/RNA-Pol inhibition, RNA-IP, RNA knockdown, native nucleosome purification across three studies","pmids":["28760200","28760199","28760201"],"confidence":"High","gaps":["Whether RNA and H3K9me3 binding are mutually exclusive on the chromodomain unresolved","Role of RNA:DNA hybrids in human SUV39H1 vs paralog not fully separated"]},{"year":2017,"claim":"Showed isoform-selective HP1α/γ interactions reciprocally stabilize Suv39h1 by inhibiting MDM2-dependent K87 ubiquitination, integrating heterochromatin proteins into stress-responsive enzyme turnover.","evidence":"Co-IP, FRAP, stability and ubiquitination assays with isoform-specific knockdown","pmids":["28059589"],"confidence":"Medium","gaps":["Single lab","Mechanism distinguishing HP1β exclusion not detailed"]},{"year":2017,"claim":"Defined SUV39H1 substrate-recognition rules and expanded its substrate repertoire to non-histone proteins including SET8, RAG2 and DOT1L, with functional consequences for H4K20 methylation.","evidence":"Peptide array specificity profiling, in vitro and cellular methylation, and SET8 activity assays","pmids":["28169523"],"confidence":"Medium","gaps":["In vivo significance of each non-histone methylation event not fully established","Single lab"]},{"year":2017,"claim":"Implicated SUV39H/HP1γ in repressing SIRT1 transcription in stressed cardiomyocytes, revealing a feedback loop between the enzyme and its own activator and a role in myocardial injury.","evidence":"ChIP, SUV39H knockout mice, and chaetocin inhibition with cardiac function readouts","pmids":["28361889"],"confidence":"Medium","gaps":["Inhibitor specificity limits attribution","Single lab"]},{"year":2017,"claim":"Showed SUV39H1 methylates the mycobacterial protein HupB to limit bacterial adhesion and survival, extending its activity to host-pathogen interaction.","evidence":"In vitro MTase assay, co-IP, adhesion and intracellular survival assays, mouse infection model","pmids":["29170282"],"confidence":"Medium","gaps":["Single lab","Physiological relevance to human TB control not established"]},{"year":2018,"claim":"Established an evolutionarily conserved automethylation autoinhibition mechanism via crystallography of the S. pombe ortholog, with a corresponding automethylated lysine in human SUV39H2.","evidence":"X-ray crystallography, biochemical MTase assays, mutagenesis, and in vivo heterochromatin analysis in S. pombe","pmids":["30051891"],"confidence":"High","gaps":["Direct demonstration of the autoinhibitory switch in human SUV39H1 not shown","Trigger relieving autoinhibition in vivo unknown"]},{"year":2018,"claim":"Identified SirT6-mediated cysteine monoubiquitination of the PRE-SET domain as a signal that releases Suv39h1 from the IκBα locus to attenuate NF-κB signaling.","evidence":"Co-IP, ubiquitination and ChIP assays with site-directed mutagenesis and NF-κB reporters","pmids":["29317652"],"confidence":"Medium","gaps":["Single lab","Generality beyond the IκBα locus untested"]},{"year":2018,"claim":"Showed CRL4-DCAF13 degrades SUV39H1 to enable H3K9me3 removal and zygotic gene activation during preimplantation development, linking enzyme turnover to embryonic reprogramming.","evidence":"Co-IP, ubiquitination assays, and Dcaf13 knockout mice with embryo arrest and IF readouts","pmids":["30111536"],"confidence":"High","gaps":["How DCAF13 selects SUV39H1 versus other substrates unclear","Relationship to MDM2/CRL4B degradation pathways unresolved"]},{"year":2024,"claim":"Identified UHRF1-deposited H3K18ub as an activating chromatin signal for SUV39H1/H2, mediating H3K9me3 accumulation at CpG island promoters and limiting the antiproliferative effect of DNMT1 inhibition.","evidence":"In vitro MTase assays on H3K18ub nucleosomes, genome-wide ChIP-seq, and UHRF1 disruption in colon cancer cells","pmids":["39631394"],"confidence":"Medium","gaps":["Structural basis of H3K18ub stimulation not resolved","Single lab"]},{"year":2024,"claim":"Demonstrated that SUV39H1 disruption in CAR T cells enhances persistence and antitumor efficacy by preserving memory programs and limiting exhaustion, defining a therapeutic application.","evidence":"CRISPR editing in human CAR T cells with scRNA-seq, scATAC-seq, and in vivo rechallenge models","pmids":["37934007"],"confidence":"Medium","gaps":["Direct chromatin targets driving the exhaustion program not pinpointed","Single lab"]},{"year":null,"claim":"How the multiple, sometimes opposing post-translational modifications and chromatin-derived signals are integrated to set SUV39H1 activity and abundance in a given cellular context remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified quantitative model linking acetylation, methylation, phosphorylation, ubiquitination and automethylation","Structure of human full-length SUV39H1 on a nucleosome not determined","Hierarchy among MDM2, CRL4B, CRL4-DCAF13 and SirT6 degradation inputs undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,1,21,27,29]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[27,28]},{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[23,24,25]},{"term_id":"GO:0042393","term_label":"histone binding","supporting_discovery_ids":[21,25]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[7,9,14,19]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[1,8,16]},{"term_id":"GO:0000228","term_label":"nuclear chromosome","supporting_discovery_ids":[0,1,8,23]},{"term_id":"GO:0005694","term_label":"chromosome","supporting_discovery_ids":[1,2,32]}],"pathway":[{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[0,3,21,23]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[7,9,14,19]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[1,18,32]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[7,9,19,31]}],"complexes":["H3K9 methyltransferase megacomplex (G9a/GLP/SETDB1/Suv39h1)","core HDAC complex (HDAC1/HDAC2/RbAp48/RbAp46)"],"partners":["HP1 (CBX5/CBX1/CBX3)","DNMT3A","DNMT1","SIRT1","MDM2","SETD7","CDK2","G9A"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O43463","full_name":"Histone-lysine N-methyltransferase SUV39H1","aliases":["Histone H3-K9 methyltransferase 1","H3-K9-HMTase 1","Lysine N-methyltransferase 1A","Position-effect variegation 3-9 homolog","Suppressor of variegation 3-9 homolog 1","Su(var)3-9 homolog 1"],"length_aa":412,"mass_kda":47.9,"function":"Histone methyltransferase that specifically mediates trimethylation of 'Lys-9' of histone H3 (H3K9me3) using monomethylated H3 'Lys-9' (H3K9me1) as substrate (PubMed:10949293, PubMed:11242053, PubMed:18004385, PubMed:40440427). Also weakly methylates histone H1 (in vitro) (PubMed:10949293). H3 'Lys-9' trimethylation represents a specific tag for epigenetic transcriptional repression by recruiting HP1 (CBX1, CBX3 and/or CBX5) proteins to methylated histones (PubMed:10949293, PubMed:11242053, PubMed:18004385). Mainly functions in heterochromatin regions, thereby playing a central role in the establishment of constitutive heterochromatin at pericentric and telomere regions (By similarity). H3 'Lys-9' trimethylation is also required to direct DNA methylation at pericentric repeats (By similarity). SUV39H1 is targeted to histone H3 via its interaction with RB1 and is involved in many processes, such as repression of MYOD1-stimulated differentiation, regulation of the control switch for exiting the cell cycle and entering differentiation, repression by the PML-RARA fusion protein, BMP-induced repression, repression of switch recombination to IgA and regulation of telomere length (PubMed:11484059, PubMed:14765126, PubMed:16449642, PubMed:16818776, PubMed:16858404, PubMed:30111536). Involved in the maintenance of H3K9me3 mark following DNA replication, when histone marks are diluted: HP1 recognizes the preexisting H3K9me3 mark and serves as a platform to recruit SUV39H1 to modify the adjacent newly incorporated histones (PubMed:10949293, PubMed:11242053, PubMed:40440427). Component of the eNoSC (energy-dependent nucleolar silencing) complex, a complex that mediates silencing of rDNA in response to intracellular energy status and acts by recruiting histone-modifying enzymes (PubMed:18485871). The eNoSC complex is able to sense the energy status of cell: upon glucose starvation, elevation of NAD(+)/NADP(+) ratio activates SIRT1, leading to histone H3 deacetylation followed by dimethylation of H3 at 'Lys-9' (H3K9me2) by SUV39H1 and the formation of silent chromatin in the rDNA locus (PubMed:18485871). Recruited by the large PER complex to the E-box elements of the circadian target genes such as PER2 itself or PER1, contributes to the conversion of local chromatin to a heterochromatin-like repressive state through H3 'Lys-9' trimethylation (By similarity) (Microbial infection) Plays a role in defense against mycobacterial infections. Methylates M.tuberculosis HupB on 'Lys-140', probably methylates HupB of M.bovis also. Methylation has an inhibitory effect on mycobacterial growth in the host. Macrophages expressing about 60% SUV39H1 are slightly more susceptible to M.bovis or M.tuberculosis infection. Chaetocin (an inhibitor of this enzyme) increases macrophage survival of M.tuberculosis. This protein inhibits biofilm formation by M.tuberculosis via 'Lys-140' trimethylation","subcellular_location":"Cytoplasmic vesicle, phagosome lumen; Cell membrane","url":"https://www.uniprot.org/uniprotkb/O43463/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SUV39H1","classification":"Not Classified","n_dependent_lines":13,"n_total_lines":1208,"dependency_fraction":0.01076158940397351},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"HMGN5","stoichiometry":0.2},{"gene":"NUMA1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/SUV39H1","total_profiled":1310},"omim":[{"mim_id":"620921","title":"ZINC FINGER PROTEIN 512; ZNF512","url":"https://www.omim.org/entry/620921"},{"mim_id":"617886","title":"ZINC FINGER PROTEIN 512B; ZNF512B","url":"https://www.omim.org/entry/617886"},{"mim_id":"616196","title":"DDB1- AND CUL4-ASSOCIATED FACTOR 13; DCAF13","url":"https://www.omim.org/entry/616196"},{"mim_id":"615818","title":"RIBOSOMAL RNA PROCESSING 8; RRP8","url":"https://www.omim.org/entry/615818"},{"mim_id":"615052","title":"ANKYRIN REPEAT- AND SOCS BOX-CONTAINING PROTEIN 7; ASB7","url":"https://www.omim.org/entry/615052"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/SUV39H1"},"hgnc":{"alias_symbol":["KMT1A"],"prev_symbol":["SUV39H"]},"alphafold":{"accession":"O43463","domains":[{"cath_id":"2.40.50.40","chopping":"43-135","consensus_level":"high","plddt":93.9669,"start":43,"end":135},{"cath_id":"2.170.270.10","chopping":"143-370","consensus_level":"high","plddt":94.049,"start":143,"end":370}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O43463","model_url":"https://alphafold.ebi.ac.uk/files/AF-O43463-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O43463-F1-predicted_aligned_error_v6.png","plddt_mean":88.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SUV39H1","jax_strain_url":"https://www.jax.org/strain/search?query=SUV39H1"},"sequence":{"accession":"O43463","fasta_url":"https://rest.uniprot.org/uniprotkb/O43463.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O43463/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O43463"}},"corpus_meta":[{"pmid":"11701123","id":"PMC_11701123","title":"Loss of the Suv39h histone methyltransferases impairs mammalian heterochromatin and genome stability.","date":"2001","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/11701123","citation_count":1404,"is_preprint":false},{"pmid":"12867029","id":"PMC_12867029","title":"Suv39h-mediated histone H3 lysine 9 methylation directs DNA methylation to major satellite repeats at pericentric heterochromatin.","date":"2003","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/12867029","citation_count":955,"is_preprint":false},{"pmid":"12711675","id":"PMC_12711675","title":"The DNA methyltransferases associate with HP1 and the SUV39H1 histone methyltransferase.","date":"2003","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/12711675","citation_count":571,"is_preprint":false},{"pmid":"18004385","id":"PMC_18004385","title":"SIRT1 regulates the histone methyl-transferase SUV39H1 during heterochromatin 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pericentric heterochromatin; Suv39h-deficient mice display impaired viability, chromosomal instabilities, increased tumor risk, and perturbed chromosome interactions during male meiosis, establishing a crucial role for pericentric H3-K9 methylation in protecting genome stability.\",\n      \"method\": \"Suv39h double-knockout mice; immunofluorescence; chromosome analysis\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic loss-of-function in mice with multiple defined cellular and organismal phenotypes, replicated across multiple assays\",\n      \"pmids\": [\"11701123\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"SUV39H1 transiently accumulates at centromeric positions during prometaphase and dissociates at the meta-to-anaphase transition; overexpression of full-length SUV39H1 induces severe mitotic defects and chromosome segregation errors and disperses the focal G2-specific distribution of phosphorylated histone H3 at serine 10; these properties depend on the C-terminal SET domain, while the N-terminal chromo domain plus first 44 amino acids direct specific accumulation at heterochromatin. The M31 (HP1β) interaction surface maps to the first 44 N-terminal amino acids.\",\n      \"method\": \"Structure-function analysis with deletion/truncation mutants in transfected cells; immunofluorescence; mitotic progression assays\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — systematic structure-function analysis with multiple defined mutants and multiple orthogonal cellular readouts\",\n      \"pmids\": [\"10779362\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"SUV39H1 selectively associates with the active centromere of a dicentric chromosome and with neocentromeres during prometaphase, and is a phosphoprotein; two additional phosphorylated isoforms appear specifically in mitotic extracts at serine and to a lesser degree threonine residues, while steady-state protein levels remain constant during the cell cycle.\",\n      \"method\": \"Cell-cycle fractionation; immunofluorescence on dicentric/neocentromere chromosomes; phosphopeptide analysis\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization experiments and biochemical detection of phosphorylation, single lab, multiple methods\",\n      \"pmids\": [\"10671371\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Suv39h-mediated H3K9 trimethylation at pericentric heterochromatin is required to direct Dnmt3b-dependent DNA methylation to major satellite repeats; in Suv39h double-null ES cells, Dnmt3b fails to localize to heterochromatic foci and displays altered DNA methylation at pericentric satellite repeats. Conversely, H3K9 trimethylation at pericentric heterochromatin is not impaired in Dnmt-deficient ES cells. Physical interaction between Dnmt3b and HP1α is also demonstrated.\",\n      \"method\": \"Suv39h double-null mouse ES cells; immunofluorescence; bisulfite sequencing; co-immunoprecipitation\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis in null cells, multiple orthogonal methods, clearly ordered pathway\",\n      \"pmids\": [\"12867029\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"SUV39H1 physically interacts with Dnmt3a (via Dnmt3a's PHD-like motif), with Dnmt1, and with HP1β both in vitro (GST pulldown) and in vivo (co-IP); SUV39H1 can purify DNA methyltransferase activity from nuclear extracts; HP1β also directly binds Dnmt1 and Dnmt3a, establishing a direct connection between the histone methylation and DNA methylation machineries.\",\n      \"method\": \"Co-immunoprecipitation (endogenous and transfected); GST pulldown; histone methyltransferase activity assay on nuclear extracts\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — reciprocal co-IP plus in vitro pulldown plus enzymatic assay, single lab, multiple methods\",\n      \"pmids\": [\"12711675\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"SUV39H1 physically interacts with HDAC1, HDAC2, and HDAC3 by co-immunoprecipitation; the N-terminal portion of SUV39H1 (not requiring its catalytic SET domain) constitutes a transcriptional repression domain that binds the core HDAC complex (HDAC1, HDAC2, RbAp48, RbAp46); repression of a heterologous promoter by SUV39H1 is dependent on histone deacetylase activity.\",\n      \"method\": \"Co-immunoprecipitation; reporter gene repression assay; HDAC inhibitor treatment\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP plus functional repression assay, single lab, two methods\",\n      \"pmids\": [\"11788710\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"The chromo shadow domain of HP1α directly interacts with the N-terminal 39 amino acid stretch of SUV39H1; a self-interaction (dimerization) of HP1α through its chromo shadow domain is required for this direct binding; a consensus peptide that disrupts chromo shadow domain dimerization also inhibits HP1α–SUV39H1 interaction.\",\n      \"method\": \"Yeast two-hybrid; GST pulldown; interaction-disrupting peptide; point mutagenesis (IY165/168EE)\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with mutagenesis, single lab\",\n      \"pmids\": [\"12565857\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Suv39h mediates H3K9 methylation at Rb/E2F target promoters specifically in differentiating (but not cycling) cells; siRNA knockdown of Suv39h prevents H3K9 methylation and subsequent repression of S-phase gene promoters in differentiating myoblasts, and Suv39h-depleted myoblasts fail to express muscle differentiation markers.\",\n      \"method\": \"Chromatin immunoprecipitation; siRNA knockdown; gene expression analysis in cycling vs. differentiating cells\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP plus RNAi loss-of-function with defined phenotypic readout, single lab\",\n      \"pmids\": [\"14765126\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"A substantial population of SUV39H1 is immobile at pericentromeric heterochromatin (FRAP analysis); the SET domain mediates this stable, structural binding to heterochromatin; recruitment of SUV39H1 to heterochromatin is at least partly independent of HP1; HP1 transiently interacts with SUV39H1 at heterochromatin (FRET).\",\n      \"method\": \"FRAP (fluorescence recovery after photobleaching); FRET; deletion mutant analysis in living cells\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — live-cell imaging with functional domain mapping, single lab, multiple methods\",\n      \"pmids\": [\"16103223\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Suv39h1 interacts with MyoD in proliferating muscle cells and its HMT activity is associated with the MyoD complex on the chromatin regulatory regions of the myogenin gene, correlating with H3K9 methylation; increased Suv39h1 represses MyoD-dependent muscle gene expression in a manner requiring both its HMT activity and its association with MyoD; siRNA-mediated abrogation of Suv39h1 activates muscle gene expression by MyoD.\",\n      \"method\": \"Co-immunoprecipitation; chromatin immunoprecipitation; overexpression; siRNA knockdown; reporter assays\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP plus co-IP plus loss-of-function RNAi with defined phenotypic readout, single lab\",\n      \"pmids\": [\"16858404\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"SIRT1 directly interacts with SUV39H1, recruits it, and deacetylates SUV39H1 at lysine 266 within its catalytic SET domain; acetylation at K266 inhibits SUV39H1 activity; SIRT1-mediated deacetylation independently contributes to elevated SUV39H1 H3K9me3 methyltransferase activity and increased H3K9me3 levels; loss of SIRT1 greatly reduces SUV39H1-dependent H3K9me3 and impairs HP1 localization.\",\n      \"method\": \"Co-immunoprecipitation; in vitro deacetylation assay; site-directed mutagenesis (K266); immunofluorescence; SIRT1 knockdown/knockout\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro biochemical assay plus site-directed mutagenesis plus cellular loss-of-function, multiple orthogonal methods\",\n      \"pmids\": [\"18004385\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Suv39H1, HP1γ, and H3K9 trimethylation are reversibly associated with the integrated HIV-1 promoter in a transcription-dependent manner and play a major role in chromatin-mediated repression of HIV-1 gene expression and post-integration latency; knockdown of HP1γ (not SUV39H1 directly) by RNA interference reactivated HIV-1 in multiple cellular models including PBMCs from HIV-1-infected donors.\",\n      \"method\": \"Chromatin immunoprecipitation; siRNA knockdown; reporter assays; primary cell models\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP plus RNAi with functional viral reactivation readout, single lab\",\n      \"pmids\": [\"17245432\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"A subset of H3K9 methyltransferases — G9a, GLP, SETDB1, and Suv39h1 — co-exist in the same megacomplex; in Suv39h or G9a null cells, the remaining HKMTs are destabilized at the protein level, indicating interdependence; all four HKMTs are recruited to major satellite repeats and to multiple G9a target genes, where they functionally cooperate.\",\n      \"method\": \"Co-immunoprecipitation; protein stability in null cells; chromatin immunoprecipitation\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP plus genetic epistasis (null cells) plus ChIP, single lab\",\n      \"pmids\": [\"20129054\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"SirT1 controls global levels of Suv39h1 by increasing its protein half-life through inhibition of MDM2-dependent polyubiquitination of Suv39h1 at lysine 87; SirT1 upregulation (e.g., under calorie restriction) increases Suv39h1 protein levels in vivo; this mechanism regulates Suv39h1 turnover at constitutive heterochromatin and ensures genome integrity.\",\n      \"method\": \"Protein stability assays; ubiquitination assays; site-directed mutagenesis (K87); co-immunoprecipitation; in vivo calorie restriction model\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — biochemical ubiquitination assay plus mutagenesis plus in vivo model, multiple orthogonal methods\",\n      \"pmids\": [\"21504832\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Snail interacts with Suv39H1 via the SNAG domain of Snail and the SET domain of Suv39H1; Snail recruits Suv39H1 to the E-cadherin promoter, leading to H3K9me3 and DNA methylation-based transcriptional repression; knockdown of Suv39H1 restores E-cadherin expression and inhibits cell migration, invasion, and metastasis of basal-like breast cancer cells.\",\n      \"method\": \"Co-immunoprecipitation; chromatin immunoprecipitation; siRNA knockdown; domain mapping; cell migration/invasion assays; in vivo metastasis assay\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP with domain mapping plus ChIP plus functional knockdown assays, single lab\",\n      \"pmids\": [\"22562246\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"SET7/9 interacts with SUV39H1 (via the chromodomain-containing region of SUV39H1) in response to adriamycin treatment; SET7/9 methylates SUV39H1 at lysines 105 and 123 (confirmed by mass spectrometry and specific antibodies); this methylation dramatically downregulates SUV39H1 methyltransferase activity, reduces H3K9me3 at heterochromatin, causes heterochromatin relaxation (increased satellite repeat transcription, increased MNase sensitivity), genome instability, and inhibits cell proliferation.\",\n      \"method\": \"Co-immunoprecipitation; GST pulldown; mass spectrometry; western blot with methylation-specific antibodies; in vitro methyltransferase assay; MNase sensitivity assay; immunofluorescence\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro enzymatic assay plus MS identification of modification sites plus multiple cellular functional assays, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"23509280\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"A-type lamins interact with SUV39H1; prelamin A/progerin exhibits enhanced binding capacity to SUV39H1 compared to mature lamin A, protecting SUV39H1 from proteasomal degradation and consequently increasing H3K9me3 levels; depletion of Suv39h1 reduces H3K9me3, restores DNA repair capacity, delays senescence in progeroid cells, and extends lifespan of Zmpste24−/− mice by ~60%.\",\n      \"method\": \"Co-immunoprecipitation; protein stability assays; siRNA/genetic Suv39h1 depletion; DNA repair assays; mouse lifespan analysis\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — co-IP plus protein stability plus genetic KO rescue with multiple phenotypic readouts including in vivo lifespan\",\n      \"pmids\": [\"23695662\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"CRL4B (containing CUL4B) associates with SUV39H1, HP1, and DNMT3A; CRL4B, through catalyzing H2AK119 monoubiquitination, facilitates SUV39H1-dependent H3K9 trimethylation and DNA methylation; depletion of CUL4B results in loss of H3K9me3 and DNA methylation at target gene promoters.\",\n      \"method\": \"Co-immunoprecipitation; chromatin immunoprecipitation; siRNA knockdown; ubiquitination assays\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP plus ChIP plus loss-of-function, single lab\",\n      \"pmids\": [\"24292684\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"CDK2 directly phosphorylates Suv39H1 at Ser391; phosphorylation levels oscillate during the cell cycle, peaking at S phase; CDK2-mediated phosphorylation at Ser391 causes preferential dissociation of Suv39H1 from chromatin, enhances occupancy of JMJD2A histone demethylase on heterochromatin, alters inactive histone marks, and phospho-mimic Suv39H1 induces early replication of heterochromatin.\",\n      \"method\": \"In vitro kinase assay; phospho-specific antibodies; cell cycle synchronization; chromatin fractionation; overexpression of phospho-mimic/phospho-defective mutants; replication timing assay\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro kinase assay plus mutagenesis plus cell-cycle-synchronized chromatin fractionation, single lab, multiple methods\",\n      \"pmids\": [\"24728993\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Suv39h1 enhances AP-2α-mediated transcriptional repression of C/EBPα during adipogenesis; Suv39h1 interacts with AP-2α and with G9a; G9a mediates H3K9me2 at the C/EBPα promoter, providing the substrate for Suv39h1-mediated H3K9me3; knockdown of Suv39h1 increases C/EBPα expression and promotes adipogenesis, while Suv39h1 overexpression impairs adipocyte differentiation.\",\n      \"method\": \"Co-immunoprecipitation; chromatin immunoprecipitation; siRNA knockdown; overexpression; differentiation assays\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP plus ChIP with sequential H3K9me2/me3 pathway dissection, single lab\",\n      \"pmids\": [\"24732798\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Suv39h-dependent H3K9me3 selectively accumulates at intact (full-length) LINE elements and ERVs (~8,150 intact LINEs/ERVs) covering ~5% of the ES cell epigenome; transcriptional repression of intact LINEs and ERVs is differentially regulated by Suv39h and other chromatin modifiers in ES cells but governed by DNA methylation in committed cells.\",\n      \"method\": \"Genome-wide ChIP sequencing in Suv39h double-null vs. wild-type mouse ES cells; bioinformatic repeat subfamily analysis\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genome-wide ChIP-seq in genetic null cells with rigorous bioinformatic analysis\",\n      \"pmids\": [\"24981170\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Suv39h1 operates through a two-step allosteric activation switch: (1) H3K9me3 recognition by its chromodomain anchors the enzyme to chromatin, (2) this anchoring allosterically promotes methyltransferase activity, enabling positive feedback spreading of H3K9me2/3 over heterochromatic regions; this mechanism was confirmed in cells using chromodomain mutants.\",\n      \"method\": \"Semi-synthetic 'designer chromatin' reconstitution with chemically defined nucleosomal substrates; in vitro methyltransferase assay; mutagenesis of chromodomain; cellular confirmation\",\n      \"journal\": \"Nature chemical biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — fully reconstituted in vitro system with designer chromatin plus mutagenesis plus cellular validation\",\n      \"pmids\": [\"26807716\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Suv39h1 promotes HP1α sumoylation both in vitro and in vivo through a region (aa1-167) distinct from its catalytic KMT domain that mediates binding to Ubc9; tethering this 1-167 domain to pericentric heterochromatin accelerates de novo targeting of HP1α to these domains; mutants unable to bind Ubc9 lack this activity.\",\n      \"method\": \"In vitro sumoylation assay; co-immunoprecipitation; tethering assay; mutagenesis\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro sumoylation assay plus cellular tethering experiment plus mutagenesis, single lab\",\n      \"pmids\": [\"27426629\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Chromatin-associated RNA (encoded partly by α-satellite sequences, retained in cis) contributes to stable association of SUV39H1 with constitutive heterochromatin; purified SUV39H1 directly binds nucleic acids through its chromodomain; nucleic acid-binding mutants of SUV39H1 and RNase treatment or RNA polymerase inhibition destabilize SUV39H1 association with chromatin in mitotic and interphase cells and cause heterochromatin function defects.\",\n      \"method\": \"In vitro nucleic acid binding assay (purified protein); chromodomain mutagenesis; RNase treatment of cells; RNA polymerase inhibition; live-cell imaging; chromatin fractionation\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro binding reconstitution plus mutagenesis plus multiple cellular perturbations, multiple orthogonal methods\",\n      \"pmids\": [\"28760200\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Suv39h2 (paralog) contains an N-terminal basic domain that facilitates retention at mitotic chromatin and provides additional affinity for major satellite repeat RNA; Suv39h1 (and Suv39h2) exclusively associate with poly-nucleosomes purified from mouse ES cells; this association is attenuated by RNaseH and entirely lost by RNaseA, indicating RNA:DNA hybrid-dependent and RNA-dependent chromatin association respectively; major satellite repeat transcripts have secondary structures favoring RNA:DNA hybrid formation.\",\n      \"method\": \"Native nucleosome purification; RNase treatment; EMSA; structural analysis of RNA\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — biochemical reconstitution with nucleosomes plus enzymatic dissection, single lab, multiple methods\",\n      \"pmids\": [\"28760199\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Suv39h1's chromodomain binds nucleic acids (higher affinity for RNA than DNA) independently of H3K9me3 recognition; Suv39h1 binds major satellite RNAs in vivo; knockdown of major satellite RNAs reduces Suv39h1 retention at pericentromere; both nucleic acid-binding and H3K9me-binding activities of Suv39h1's chromodomain are required for pericentric heterochromatin assembly.\",\n      \"method\": \"EMSA with purified chromodomain; RNA immunoprecipitation in vivo; RNA knockdown; chromodomain mutagenesis; immunofluorescence\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro binding assay plus mutagenesis plus in vivo RNA-IP and RNA knockdown, multiple orthogonal methods\",\n      \"pmids\": [\"28760201\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"SUV39H cooperates with HP1γ to catalyze H3K9 trimethylation on the SIRT1 promoter, thereby repressing SIRT1 transcription in cardiomyocytes under ischemic/oxidative stress; SUV39H knockout mice are protected from myocardial infarction, and SUV39H inhibition attenuates cardiac injury following MI; SUV39H augments intracellular ROS levels in a SIRT1-dependent manner.\",\n      \"method\": \"Chromatin immunoprecipitation; SUV39H knockout mice; pharmacological inhibition (chaetocin); gene expression analysis; cardiac function measurement\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO plus ChIP plus pharmacological inhibition with defined molecular mechanism, single lab\",\n      \"pmids\": [\"28361889\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"SUV39H1 substrate specificity requires recognition of H3 residues between K4 and G12, with highly specific readout of R8; SUV39H1 methylates non-histone substrates including RAG2, SET8, and DOT1L in cells; methylation of SET8 allosterically stimulates its H4K20 monomethylation activity, connecting SUV39H1 to increased H4K20me3; methylation of RAG2 alters its subnuclear localization.\",\n      \"method\": \"Peptide array substrate specificity profiling; in vitro methyltransferase assay at protein level; cellular methylation confirmation; functional activity assay for SET8\",\n      \"journal\": \"ACS chemical biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro enzymatic assay plus cellular validation, single lab, multiple substrates\",\n      \"pmids\": [\"28169523\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"SUV39H1 methylates the mycobacterial histone-like protein HupB; this trimethylation reduces the cell adhesion capability of mycobacteria and reduces mycobacterial survival inside host cells and biofilm formation; SUV39H1 associates with mycobacterial bacilli during infection.\",\n      \"method\": \"In vitro methyltransferase assay; co-immunoprecipitation; bacterial adhesion assays; intracellular survival assays; mouse infection model\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro enzymatic assay plus cellular and in vivo functional assays, single lab\",\n      \"pmids\": [\"29170282\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Automethylation of specific lysines in an internal loop of Clr4 (the S. pombe ortholog of SUV39H) inhibits catalytic activity by blocking the H3K9 substrate-binding pocket; automethylation promotes a conformational switch that enhances H3K9me activity; mutations disrupting this regulation lead to aberrant H3K9me and epigenetic instability; a corresponding lysine in human SUV39H2 is also automethylated, suggesting conserved mechanism.\",\n      \"method\": \"X-ray crystallography; biochemical methyltransferase assays; mutagenesis; in vivo heterochromatin analysis in S. pombe\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure plus biochemical reconstitution plus mutagenesis plus in vivo validation, multiple orthogonal methods\",\n      \"pmids\": [\"30051891\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"SirT6 binds to Suv39h1 and induces monoubiquitination of conserved cysteines in the PRE-SET domain of Suv39h1; following NF-κB signaling activation, Suv39h1 is released from the IκBα locus; SirT6-mediated cysteine monoubiquitination of Suv39h1 attenuates NF-κB pathway activity through IκBα upregulation.\",\n      \"method\": \"Co-immunoprecipitation; ubiquitination assay; chromatin immunoprecipitation; site-directed mutagenesis; NF-κB reporter assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP plus ChIP plus ubiquitination assay with mutagenesis, single lab\",\n      \"pmids\": [\"29317652\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"CRL4-DCAF13 E3 ubiquitin ligase targets SUV39H1 for polyubiquitination and proteasomal degradation; Dcaf13 knockout embryos are arrested at the 8–16 cell stage with high levels of H3K9me3; DCAF13-mediated SUV39H1 degradation facilitates H3K9me3 removal and zygotic gene expression during preimplantation development.\",\n      \"method\": \"Co-immunoprecipitation; ubiquitination assays; Dcaf13 knockout mice; embryo arrest phenotype; immunofluorescence\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with defined developmental arrest phenotype plus biochemical ubiquitination assay, multiple methods\",\n      \"pmids\": [\"30111536\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"SUV39H1 orchestrates temporal dynamics of H3K9 methylation at the centromere during chromosome segregation; inhibition of SUV39H1 methylation dynamics perturbs chromosome congression, causes a brief increase in Aurora B kinase activity, enrichment of MCAK at centromeres, kinetochore-microtubule destabilization, reduced tension across sister kinetochores, and chromosome misalignment.\",\n      \"method\": \"FRET-based methylation sensors targeted to centromeres in living HeLa cells; immunofluorescence; pharmacological SUV39H1 inhibition (chaetocin)\",\n      \"journal\": \"Journal of molecular cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — live-cell FRET sensors plus pharmacological perturbation, single lab\",\n      \"pmids\": [\"22831836\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"N-terminally truncated Suv39h1 (ΔN, HP1-binding defective) introduced into Suv39h-deficient ES cells recovers pericentric H3K9me3 and Dnmt3a/3b accumulation and DNA methylation at pericentromeres, but only marginally restores HP1 accumulation; Suv39h-HP1 direct binding is dispensable for pericentric H3K9me3 and DNA methylation but is required for full HP1 recruitment and complete heterochromatin features (ATRX association, H4K20me3).\",\n      \"method\": \"Reconstitution of truncation mutants in Suv39h-null ES cells; immunofluorescence; ChIP; bisulfite sequencing\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic reconstitution with defined mutants in null cells, multiple readouts, single lab\",\n      \"pmids\": [\"23836914\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"HP1α and HP1γ (but not HP1β) preferentially interact in vivo with Suv39h1 and regulate its dynamics and stability at heterochromatin by inhibiting MDM2-dependent Suv39h1-K87 polyubiquitination; reciprocally, Suv39h1 increases HP1α stability; loss of HP1α and γ inhibits stress-induced upregulation of Suv39h1 and H3K9me3; Suv39h1 deficiency abrogates stress-dependent upregulation of HP1α and γ.\",\n      \"method\": \"Co-immunoprecipitation; FRAP; protein stability assays; ubiquitination assays; isoform-specific knockdown\",\n      \"journal\": \"Epigenetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple co-IPs plus protein stability assays plus FRAP, single lab\",\n      \"pmids\": [\"28059589\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"H3K18ub (catalyzed by UHRF1) enhances SUV39H1/H2 methyltransferase activity; disrupting H3K18ub-dependent SUV39H1/H2 activity prevents H3K9me3 accumulation at CpG island promoters following DNMT1 inhibition and enhances transcriptional activating and antiproliferative effects of DNMT1 inhibition.\",\n      \"method\": \"Genome-wide ChIP-seq; in vitro methyltransferase activity assay with H3K18ub nucleosomes; genetic disruption of UHRF1; colon cancer cell models\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro enzymatic assay plus genome-wide ChIP-seq plus genetic perturbation, single lab\",\n      \"pmids\": [\"39631394\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Genetic disruption of SUV39H1 in CAR T cells enhances early expansion, long-term persistence, and antitumor efficacy in leukemia and prostate cancer models; SUV39H1-edited CAR T cells show improved memory transcription factor accessibility, reduced inhibitory receptor expression, and reduced exhaustion upon multiple tumor rechallenges.\",\n      \"method\": \"Genetic CRISPR editing of SUV39H1 in human CAR T cells; scRNA-seq; scATAC-seq; in vivo tumor rechallenge models\",\n      \"journal\": \"Cancer discovery\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic loss-of-function with scRNA-seq/scATAC-seq profiling plus in vivo tumor models, single lab\",\n      \"pmids\": [\"37934007\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SUV39H1 (KMT1A) is an H3K9-specific histone methyltransferase whose SET domain catalyzes di- and trimethylation of H3K9 to establish constitutive and facultative heterochromatin; its activity is regulated by multiple PTMs (SIRT1-mediated deacetylation at K266 activates it, SET7/9-mediated methylation at K105/K123 inhibits it, CDK2-mediated phosphorylation at S391 releases it from chromatin, and MDM2-dependent polyubiquitination at K87 targets it for degradation); it is stably tethered to pericentric heterochromatin through its SET domain and through chromodomain-mediated binding of both H3K9me3 and chromatin-associated RNA (including major satellite/α-satellite transcripts); it interacts directly with HP1 proteins (via its N-terminal 39 residues), HDACs, DNMT3a/Dnmt3b, and numerous transcription factors (Rb/E2F, Snail, MyoD, RUNX1, EVI1, CIITA, and others) to repress gene expression; it also methylates non-histone substrates including RAG2, SET8, and DOT1L; its H3K9me3 mark directs Dnmt3b-dependent DNA methylation to pericentric satellite repeats, silences intact LINE retrotransposons in ES cells, and is required for genome stability and faithful chromosome segregation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SUV39H1 is a SET-domain histone methyltransferase that establishes constitutive heterochromatin by trimethylating histone H3 at lysine 9 (H3K9me3) at pericentric regions, an activity required to protect genome stability and ensure faithful chromosome segregation [#0, #1]. Its substrate engagement depends on recognition of H3 residues flanking K9, with strict readout of R8 [#27]. Stable tethering to heterochromatin is achieved through two complementary modules: the SET domain mediates structural, near-immobile binding to pericentric chromatin, while the chromodomain recognizes both pre-existing H3K9me3 and chromatin-associated RNA, including major satellite/\\u03b1-satellite transcripts that retain the enzyme in cis [#8, #21, #23, #25]. Chromodomain-based H3K9me3 reading also drives a two-step allosteric activation switch, anchoring the enzyme and stimulating catalysis to spread H3K9me2/3 by positive feedback [#21]. SUV39H1-deposited H3K9me3 in turn directs Dnmt3b-dependent DNA methylation to pericentric satellite repeats and silences intact LINE/ERV retrotransposons in ES cells, with the histone and DNA methylation machineries physically bridged through direct interactions with DNMT3a, DNMT1, and HP1 proteins [#3, #4, #20]. SUV39H1 functions within a larger H3K9 methyltransferase network (G9a, GLP, SETDB1) whose members are mutually stabilized and co-recruited to satellite repeats [#12], and it cooperates with HP1 both by binding via its N-terminal residues and by promoting HP1\\u03b1 sumoylation to seed de novo HP1 targeting [#6, #22, #33]. Beyond bulk heterochromatin, it is recruited by sequence-specific transcription factors\\u2014including the Rb/E2F axis in differentiating myoblasts, MyoD, AP-2\\u03b1, and Snail\\u2014to deposit repressive H3K9me3 at defined promoters governing cell differentiation, EMT, and metastasis [#7, #9, #14, #19]. Its activity is tightly controlled by post-translational modification: SIRT1-mediated deacetylation at K266 activates the enzyme and stabilizes it by blocking MDM2-dependent K87 polyubiquitination, SET7/9-mediated methylation at K105/K123 inhibits it, CDK2 phosphorylation at S391 releases it from chromatin during S phase, and conserved automethylation autoinhibits catalysis [#10, #13, #15, #18, #29]. SUV39H1 additionally methylates non-histone substrates such as SET8, RAG2, and DOT1L [#27].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Established that SUV39H1 dynamically localizes to centromeres during mitosis and that its two ends carry separable functions, framing a model in which an N-terminal targeting region and a C-terminal catalytic domain coordinate heterochromatin function.\",\n      \"evidence\": \"Cell-cycle fractionation, immunofluorescence on dicentric/neocentromere chromosomes, and structure-function analysis with truncation mutants in transfected cells\",\n      \"pmids\": [\"10779362\", \"10671371\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not establish the enzymatic mark deposited in vivo\", \"Phosphorylation sites and responsible kinases unmapped\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Demonstrated genetically that Suv39h enzymes deposit pericentric H3K9 trimethylation and that this mark is essential for genome stability, defining the core biological role.\",\n      \"evidence\": \"Suv39h double-knockout mice with chromosome instability, tumor risk, and meiotic defects\",\n      \"pmids\": [\"11701123\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of recruitment to pericentric chromatin not resolved\", \"Downstream effectors of instability undefined\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Showed that SUV39H1-dependent H3K9me3 acts upstream of DNA methylation by recruiting Dnmt3b, and physically connected the histone and DNA methylation machineries via HP1 and DNMT interactions.\",\n      \"evidence\": \"Genetic epistasis in Suv39h-null ES cells, bisulfite sequencing, co-IP and GST pulldown with Dnmt3a/Dnmt1/HP1\\u03b2\",\n      \"pmids\": [\"12867029\", \"12711675\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry and ordering of the histone-DNA methyltransferase complex unresolved\", \"Whether interactions occur simultaneously in one complex untested\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Linked SUV39H1 to deacetylase-dependent transcriptional repression, identifying an N-terminal repression domain functioning independently of catalysis.\",\n      \"evidence\": \"Co-IP with HDAC1/2/3 and reporter repression assays sensitive to HDAC inhibition\",\n      \"pmids\": [\"11788710\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab, two methods\", \"Genomic targets of the HDAC-coupled repression not mapped\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Defined a context-specific recruitment mode in which Suv39h methylates Rb/E2F target promoters selectively in differentiating cells, coupling heterochromatin machinery to cell-fate decisions.\",\n      \"evidence\": \"ChIP plus siRNA knockdown with differentiation readouts in myoblasts\",\n      \"pmids\": [\"14765126\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct recruitment factor at these promoters not identified here\", \"Single lab\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Resolved the basis of stable heterochromatin tethering, showing the SET domain confers immobile structural binding largely independent of HP1.\",\n      \"evidence\": \"FRAP and FRET with deletion mutants in living cells\",\n      \"pmids\": [\"16103223\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular partner mediating SET-dependent anchoring not identified\", \"Transient versus stable HP1 contributions only qualitatively defined\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Extended factor-directed recruitment by showing Suv39h1 binds MyoD and represses muscle gene expression through HMT activity on target chromatin.\",\n      \"evidence\": \"Co-IP, ChIP, overexpression and siRNA with reporter and differentiation assays\",\n      \"pmids\": [\"16858404\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Interplay with the Rb/E2F differentiation pathway not integrated\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Identified SIRT1 deacetylation at K266 as a direct activating switch for SUV39H1 catalysis, establishing the first PTM control of enzyme activity.\",\n      \"evidence\": \"Co-IP, in vitro deacetylation, K266 mutagenesis, and SIRT1 loss-of-function\",\n      \"pmids\": [\"18004385\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Acetyltransferase responsible for K266 acetylation not identified\", \"Quantitative contribution to global H3K9me3 unclear\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Implicated the SUV39H1/HP1\\u03b3/H3K9me3 axis in chromatin-mediated silencing of integrated HIV-1, extending heterochromatin function to viral latency.\",\n      \"evidence\": \"ChIP, siRNA, and reporter assays in cellular and primary HIV-1 models\",\n      \"pmids\": [\"17245432\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct SUV39H1 knockdown reactivation not demonstrated\", \"Single lab\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Placed SUV39H1 within a co-dependent megacomplex of H3K9 methyltransferases that are mutually stabilized and co-recruited to satellite and gene targets.\",\n      \"evidence\": \"Co-IP, protein stability in null cells, and ChIP\",\n      \"pmids\": [\"20129054\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Architecture and direct contacts within the megacomplex unresolved\", \"Single lab\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Showed SIRT1 controls SUV39H1 abundance by blocking MDM2-dependent K87 polyubiquitination, linking enzyme stability to nutrient state.\",\n      \"evidence\": \"Ubiquitination and stability assays, K87 mutagenesis, and an in vivo calorie restriction model\",\n      \"pmids\": [\"21504832\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How SIRT1 inhibits MDM2 toward this substrate not detailed\", \"Other E3 contributions not excluded\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Demonstrated that SUV39H1 methylation dynamics at the centromere are required for proper kinetochore-microtubule attachment and chromosome congression, mechanistically connecting H3K9 methylation to error-free segregation.\",\n      \"evidence\": \"Centromere-targeted FRET methylation sensors and chaetocin inhibition in living HeLa cells\",\n      \"pmids\": [\"22831836\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Pharmacological inhibitor specificity limits attribution\", \"Link to Aurora B/MCAK pathway correlative\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identified Snail as a recruiter of SUV39H1 to the E-cadherin promoter, defining an EMT/metastasis-promoting repression mechanism via SET-SNAG domain interaction.\",\n      \"evidence\": \"Co-IP with domain mapping, ChIP, knockdown, and in vivo metastasis assays in breast cancer cells\",\n      \"pmids\": [\"22562246\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Generality across other EMT transcription factors untested here\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Discovered SET7/9-mediated methylation of SUV39H1 at K105/K123 as an inhibitory PTM that relaxes heterochromatin under DNA damage, adding a counterbalancing control to SIRT1 activation.\",\n      \"evidence\": \"Co-IP, mass spectrometry, methylation-specific antibodies, in vitro MTase and MNase sensitivity assays\",\n      \"pmids\": [\"23509280\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological signals beyond adriamycin not defined\", \"Crosstalk with K266 acetylation not integrated\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Showed that A-type lamins (and progerin) stabilize SUV39H1, and that Suv39h1 depletion delays senescence and extends lifespan in progeroid mice, tying heterochromatin maintenance to aging.\",\n      \"evidence\": \"Co-IP, stability assays, genetic depletion with DNA repair, senescence and Zmpste24-/- lifespan readouts\",\n      \"pmids\": [\"23695662\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which lamin binding blocks degradation not detailed\", \"Relationship to MDM2/CRL4 pathways unresolved\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Established CRL4B/H2AK119ub as an upstream facilitator of SUV39H1-dependent H3K9me3 and DNA methylation, adding a ubiquitin-dependent chromatin crosstalk layer.\",\n      \"evidence\": \"Co-IP with SUV39H1/HP1/DNMT3A, ChIP, knockdown, and ubiquitination assays\",\n      \"pmids\": [\"24292684\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct versus indirect facilitation not separated\", \"Single lab\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Dissected the HP1-binding contribution by showing direct Suv39h-HP1 binding is dispensable for pericentric H3K9me3/DNA methylation but needed for full HP1 recruitment and complete heterochromatin features.\",\n      \"evidence\": \"Reconstitution of \\u0394N truncation mutants in Suv39h-null ES cells with IF, ChIP and bisulfite sequencing\",\n      \"pmids\": [\"23836914\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Alternative HP1-independent targeting determinant not identified here\", \"Single lab\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Identified CDK2 phosphorylation at S391 as a cell-cycle switch that evicts Suv39h1 from chromatin in S phase, allowing demethylase access and altered replication timing.\",\n      \"evidence\": \"In vitro kinase assay, phospho-specific antibodies, synchronized chromatin fractionation, and phospho-mimic mutants\",\n      \"pmids\": [\"24728993\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Phosphatase reversing S391 not identified\", \"Coordination with other PTMs across the cycle unmapped\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Mapped the Suv39h-dependent H3K9me3 landscape genome-wide, showing selective silencing of intact LINE/ERV retrotransposons in ES cells.\",\n      \"evidence\": \"Genome-wide ChIP-seq in Suv39h double-null versus wild-type ES cells with repeat subfamily analysis\",\n      \"pmids\": [\"24981170\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Determinants of selectivity for intact elements unresolved\", \"Handoff to DNA methylation in committed cells only inferred\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Extended factor-directed repression to adipogenesis, showing Suv39h1 cooperates with AP-2\\u03b1 and G9a in a sequential H3K9me2-to-me3 pathway at the C/EBP\\u03b1 promoter.\",\n      \"evidence\": \"Co-IP, ChIP, knockdown and overexpression with differentiation assays\",\n      \"pmids\": [\"24732798\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Ordering of AP-2\\u03b1 versus G9a recruitment correlative\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Defined the two-step allosteric activation mechanism whereby chromodomain reading of H3K9me3 anchors the enzyme and stimulates catalysis to drive feedback spreading of the mark.\",\n      \"evidence\": \"Semi-synthetic designer chromatin reconstitution, in vitro MTase assays, chromodomain mutagenesis, cellular validation\",\n      \"pmids\": [\"26807716\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How spreading is bounded at heterochromatin borders unresolved\", \"Integration with RNA-binding by the same domain not addressed here\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Revealed a catalysis-independent function in which Suv39h1 binds Ubc9 to promote HP1\\u03b1 sumoylation and seed de novo HP1 targeting.\",\n      \"evidence\": \"In vitro sumoylation, co-IP, heterochromatin tethering, and Ubc9-binding mutants\",\n      \"pmids\": [\"27426629\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Relative contribution versus H3K9me3-driven HP1 recruitment unclear\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Established that chromatin-associated RNA, including \\u03b1-satellite/major satellite transcripts, binds the chromodomain to retain SUV39H1 at heterochromatin, defining an RNA-dependent tethering mechanism distinct from H3K9me3 reading.\",\n      \"evidence\": \"In vitro nucleic acid binding, chromodomain mutagenesis, RNase/RNA-Pol inhibition, RNA-IP, RNA knockdown, native nucleosome purification across three studies\",\n      \"pmids\": [\"28760200\", \"28760199\", \"28760201\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether RNA and H3K9me3 binding are mutually exclusive on the chromodomain unresolved\", \"Role of RNA:DNA hybrids in human SUV39H1 vs paralog not fully separated\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Showed isoform-selective HP1\\u03b1/\\u03b3 interactions reciprocally stabilize Suv39h1 by inhibiting MDM2-dependent K87 ubiquitination, integrating heterochromatin proteins into stress-responsive enzyme turnover.\",\n      \"evidence\": \"Co-IP, FRAP, stability and ubiquitination assays with isoform-specific knockdown\",\n      \"pmids\": [\"28059589\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Mechanism distinguishing HP1\\u03b2 exclusion not detailed\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Defined SUV39H1 substrate-recognition rules and expanded its substrate repertoire to non-histone proteins including SET8, RAG2 and DOT1L, with functional consequences for H4K20 methylation.\",\n      \"evidence\": \"Peptide array specificity profiling, in vitro and cellular methylation, and SET8 activity assays\",\n      \"pmids\": [\"28169523\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo significance of each non-histone methylation event not fully established\", \"Single lab\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Implicated SUV39H/HP1\\u03b3 in repressing SIRT1 transcription in stressed cardiomyocytes, revealing a feedback loop between the enzyme and its own activator and a role in myocardial injury.\",\n      \"evidence\": \"ChIP, SUV39H knockout mice, and chaetocin inhibition with cardiac function readouts\",\n      \"pmids\": [\"28361889\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Inhibitor specificity limits attribution\", \"Single lab\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Showed SUV39H1 methylates the mycobacterial protein HupB to limit bacterial adhesion and survival, extending its activity to host-pathogen interaction.\",\n      \"evidence\": \"In vitro MTase assay, co-IP, adhesion and intracellular survival assays, mouse infection model\",\n      \"pmids\": [\"29170282\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Physiological relevance to human TB control not established\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Established an evolutionarily conserved automethylation autoinhibition mechanism via crystallography of the S. pombe ortholog, with a corresponding automethylated lysine in human SUV39H2.\",\n      \"evidence\": \"X-ray crystallography, biochemical MTase assays, mutagenesis, and in vivo heterochromatin analysis in S. pombe\",\n      \"pmids\": [\"30051891\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct demonstration of the autoinhibitory switch in human SUV39H1 not shown\", \"Trigger relieving autoinhibition in vivo unknown\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identified SirT6-mediated cysteine monoubiquitination of the PRE-SET domain as a signal that releases Suv39h1 from the I\\u03baB\\u03b1 locus to attenuate NF-\\u03baB signaling.\",\n      \"evidence\": \"Co-IP, ubiquitination and ChIP assays with site-directed mutagenesis and NF-\\u03baB reporters\",\n      \"pmids\": [\"29317652\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Generality beyond the I\\u03baB\\u03b1 locus untested\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Showed CRL4-DCAF13 degrades SUV39H1 to enable H3K9me3 removal and zygotic gene activation during preimplantation development, linking enzyme turnover to embryonic reprogramming.\",\n      \"evidence\": \"Co-IP, ubiquitination assays, and Dcaf13 knockout mice with embryo arrest and IF readouts\",\n      \"pmids\": [\"30111536\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How DCAF13 selects SUV39H1 versus other substrates unclear\", \"Relationship to MDM2/CRL4B degradation pathways unresolved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identified UHRF1-deposited H3K18ub as an activating chromatin signal for SUV39H1/H2, mediating H3K9me3 accumulation at CpG island promoters and limiting the antiproliferative effect of DNMT1 inhibition.\",\n      \"evidence\": \"In vitro MTase assays on H3K18ub nucleosomes, genome-wide ChIP-seq, and UHRF1 disruption in colon cancer cells\",\n      \"pmids\": [\"39631394\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural basis of H3K18ub stimulation not resolved\", \"Single lab\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Demonstrated that SUV39H1 disruption in CAR T cells enhances persistence and antitumor efficacy by preserving memory programs and limiting exhaustion, defining a therapeutic application.\",\n      \"evidence\": \"CRISPR editing in human CAR T cells with scRNA-seq, scATAC-seq, and in vivo rechallenge models\",\n      \"pmids\": [\"37934007\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct chromatin targets driving the exhaustion program not pinpointed\", \"Single lab\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the multiple, sometimes opposing post-translational modifications and chromatin-derived signals are integrated to set SUV39H1 activity and abundance in a given cellular context remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified quantitative model linking acetylation, methylation, phosphorylation, ubiquitination and automethylation\", \"Structure of human full-length SUV39H1 on a nucleosome not determined\", \"Hierarchy among MDM2, CRL4B, CRL4-DCAF13 and SirT6 degradation inputs undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 1, 21, 27, 29]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [27, 28]},\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [23, 24, 25]},\n      {\"term_id\": \"GO:0042393\", \"supporting_discovery_ids\": [21, 25]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [7, 9, 14, 19]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [1, 8, 16]},\n      {\"term_id\": \"GO:0000228\", \"supporting_discovery_ids\": [0, 1, 8, 23]},\n      {\"term_id\": \"GO:0005694\", \"supporting_discovery_ids\": [1, 2, 32]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [0, 3, 21, 23]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [7, 9, 14, 19]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [1, 18, 32]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [7, 9, 19, 31]}\n    ],\n    \"complexes\": [\n      \"H3K9 methyltransferase megacomplex (G9a/GLP/SETDB1/Suv39h1)\",\n      \"core HDAC complex (HDAC1/HDAC2/RbAp48/RbAp46)\"\n    ],\n    \"partners\": [\n      \"HP1 (CBX5/CBX1/CBX3)\",\n      \"DNMT3A\",\n      \"DNMT1\",\n      \"SIRT1\",\n      \"MDM2\",\n      \"SETD7\",\n      \"CDK2\",\n      \"G9a\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":9,"faith_total":9,"faith_pct":100.0}}