Project description:The MLL gene is a common target of chromosomal translocations found in human leukemia. MLL-fusion leukemias are consistently poor prognosis. One of the most common translocation partners is AF9 (a.k.a. MLLT3). MLL-AF9 recruits DOT1L, a histone 3 lysine 79 methyltransferase (H3K79me1/me2/me3), leading to aberrant gene transcription. We show that DOT1L has three AF9 binding sites, and present the NMR solution structure of a DOT1L-AF9 complex. We generated structure-guided point mutations with graded effects on recruitment of DOT1L to MLL-AF9. ChIP-Seq analyses of H3K79me2 and H3K79me3 show that graded reduction of the DOT1L interaction with MLL-AF9 results in selective losses in H3K79me2 and me3 marks at MLL-AF9 target genes. Furthermore, the degree of DOT1L recruitment defines the level of MLL-AF9 hematopoietic transformation. Hematopoietic progenitor cells isolated from mouse bone marrow were transduced with retrovirus expressing either wildtype MLL-AF9 (WT), mutants, MLL-AF9 (D544R) and MLL-AF9 (D546R). ChIP-Seq analyses were performed on these wildtype and mutant cells using H3K79me2 and H3K79me3 antibodies. 3 samples corresponding to ChIP-Seq with H3K79me2 antibody: 1) MLL-AF9 (WT) 2) MLL-AF9 (D544R) 3) MLL-AF9 (D546R) 3 Samples Corresponding to ChIP-Seq with H3K79me3 antibody: 4) MLL-AF9 (WT) 5) MLL-AF9 (D544R) 6) MLL-AF9 (D546R)
Project description:DOT1L-catalyzed H3K79 methylation is a hallmark of actively transcribed genes and has been extensively studied in developmental and disease contexts. While DOT1L inhibition has emerged as a promising therapeutic strategy in cancer, its role in pro-atherogenic endothelial inflammation remains unclear. To investigate this, we utilized an in vivo partial carotid artery ligation model and observed increased DOT1L expression and H3K79me3 level. Consistently, in vitro studies employing a 3D-printed human coronary artery model and TNF-α stimulation corroborated these results, showing elevated DOT1L expression and H3K79me3 deposition, while levels of H3K79me and me2 remained unchanged. Further analyses identified key DotCom complex components, AF10 and AF9 (upregulated) and AF17 (downregulated), as contributors to the enhanced H3K79me3 landscape. CUT&RUN sequencing showed prominent H3K79me3 enrichment at the RELA (NF-κB p65) promoter, corresponding with increased NF-κB p65 expression and activation. Notably, inhibition/knockdown of the methyltransferase DOT1L or overexpression of the demethylase FBXL10 significantly reduced H3K79me3 levels, thereby suppressing NF-κB p65 expression and attenuating endothelial inflammation, independent of canonical NF-κB p65 activation. These findings establish DOT1L-mediated H3K79me3 as a crucial epigenetic regulator of endothelial inflammation, highlighting a potential therapeutic avenue for mitigating NF-κB p65-driven pro-atherogenic endothelial dysfunction.
Project description:This study describes the epigenetic profiling of the novel interactors of H3K4me3, H3K36me3 or H3K9me3. The interactors were ChIP-Seq profiled by their GFP tag in stably transfected HeLa (Kyoto) cells. The interactors include GATAD1, Sgf29, BAP18, TRRAP, PHF8, N-PAC and LRWD1 (including replicates), as well as an GFP ChIP-Seq profile on non-transfected HeLa cells (negative control). Also included are the profiles of the histone modifications themselves (H3K4me3, H3K27me3, H3K9me3, H3K36me3, H3K9/14Ac and H3K79me3)
Project description:The glycolytic enzyme, pyruvate kinase Pyk1 maintains telomere heterochromatin by phosphorylating histone H3T11 (H3pT11), which promotes SIR (silent information regulator) complex binding at telomeres and prevents autophagy-mediated Sir2 degradation. However, the exact action mechanism of H3pT11 is poorly understood. Here, we identify Dot1-catalyzed H3K79 tri-methylation (H3K79me3) as the downstream effector of H3pT11 and uncover how this histone crosstalk regulates autophagy and telomere silencing. Mechanistically, Pyk1-catalyzed H3pT11 directly reduces the binding of Dot1 to chromatin and inhibits Dot1-catalyzed H3K79me3, which leads to transcriptional repression of autophagy genes and reduced autophagy. Despite the antagonism between H3pT11 and H3K79me3, they synergically promote the binding of SIR complex at telomeres to maintain telomere silencing. Furthermore, we identify Reb1 as a telomere-associated factor that recruits Pyk1-containing SESAME (Serine-responsive SAM-containing Metabolic Enzyme) complex to telomere regions to phosphorylate H3T11 and prevent the invasion of H3K79me3 from euchromatin into heterochromatin to maintain telomere silencing. Together, these results uncover a novel histone crosstalk and provide insights into dynamic regulation of silent heterochromatin and autophagy in response to cell metabolism.
Project description:The glycolytic enzyme, pyruvate kinase Pyk1 maintains telomere heterochromatin by phosphorylating histone H3T11 (H3pT11), which promotes SIR (silent information regulator) complex binding at telomeres and prevents autophagy-mediated Sir2 degradation. However, the exact action mechanism of H3pT11 is poorly understood. Here, we identify Dot1-catalyzed H3K79 tri-methylation (H3K79me3) as the downstream effector of H3pT11 and uncover how this histone crosstalk regulates autophagy and telomere silencing. Mechanistically, Pyk1-catalyzed H3pT11 directly reduces the binding of Dot1 to chromatin and inhibits Dot1-catalyzed H3K79me3, which leads to transcriptional repression of autophagy genes and reduced autophagy. Despite the antagonism between H3pT11 and H3K79me3, they synergically promote the binding of SIR complex at telomeres to maintain telomere silencing. Furthermore, we identify Reb1 as a telomere-associated factor that recruits Pyk1-containing SESAME (Serine-responsive SAM-containing Metabolic Enzyme) complex to telomere regions to phosphorylate H3T11 and prevent the invasion of H3K79me3 from euchromatin into heterochromatin to maintain telomere silencing. Together, these results uncover a novel histone crosstalk and provide insights into dynamic regulation of silent heterochromatin and autophagy in response to cell metabolism.
Project description:The glycolytic enzyme, pyruvate kinase Pyk1 maintains telomere heterochromatin by phosphorylating histone H3T11 (H3pT11), which promotes SIR (silent information regulator) complex binding at telomeres and prevents autophagy-mediated Sir2 degradation. However, the exact action mechanism of H3pT11 is poorly understood. Here, we identify Dot1-catalyzed H3K79 tri-methylation (H3K79me3) as the downstream effector of H3pT11 and uncover how this histone crosstalk regulates autophagy and telomere silencing. Mechanistically, Pyk1-catalyzed H3pT11 directly reduces the binding of Dot1 to chromatin and inhibits Dot1-catalyzed H3K79me3, which leads to transcriptional repression of autophagy genes and reduced autophagy. Despite the antagonism between H3pT11 and H3K79me3, they synergically promote the binding of SIR complex at telomeres to maintain telomere silencing. Furthermore, we identify Reb1 as a telomere-associated factor that recruits Pyk1-containing SESAME (Serine-responsive SAM-containing Metabolic Enzyme) complex to telomere regions to phosphorylate H3T11 and prevent the invasion of H3K79me3 from euchromatin into heterochromatin to maintain telomere silencing. Together, these results uncover a novel histone crosstalk and provide insights into dynamic regulation of silent heterochromatin and autophagy in response to cell metabolism.