Project description:In order to understand the role of H3K79me2 and DOT1L during CNS development, we analysed neural stem cells after pharmacological inhibition of DOT1L (5 µM SGC0946). To identify target genes of DOT1L in the cortex, we determined the transcriptome of cortical progenitor cells derived from E14.5 NMRI mice after interference with DOT1L activity for three days in vitro (DIV3). Therefore, three independent experiments were performed (ctrl1 – inh1, ctrl2 – inh2, ctrl3 – inh3).
Project description:Disruptor of telomeric silencing 1-like (DOT1L) expression is elevated in many cancer types including ovarian cancer. Therefore, we analyzed the role of DOT1L in ovarian cancer. Pharmacological inhibition of DOT1L expression in ovarian cancer cell lines resulted in decreased proliferation, and increased cell death.
Project description:Disruptor of telomeric silencing 1-like (DOT1L) is the specific and sole methyltransferase for H3K79. However, the role of Dot1l in T cells is not well determined. Here, used CD4-Cre/Dot1lflox/flox mice to specifically delete DOT1L in T cells. The genes characteristics were determined by RNA array and compared to wild type cells. We used microarrays to detail the global gene expression in Dot1l knockout and wild type CD8+ T cells.
Project description:Many repetitive DNA elements are packaged in heterochromatin, but depend on occasional transcription to maintain long-term silencing. The factors that promote transcription of repeat elements in heterochromatin are largely unknown. Here, we show that DOT1L, a histone methyltransferase that modifies lysine 79 of histone H3 (H3K79), is required for transcription of major satellite repeats to maintain pericentromeric heterochromatin (PCH), and that this function is essential for preimplantation development. DOT1L is a transcriptional activator at single-copy genes but does not have a known role in repeat element transcription. We show that H3K79me3 is specifically enriched at repetitive elements, that loss of DOT1L compromises pericentromeric major satellite transcription, and that this function depends on interaction between DOT1L and the chromatin remodeler SMARCA5. DOT1L inhibition causes chromosome breaks and cell cycle defects, and leads to embryonic lethality. Together, our findings uncover a vital new role for DOT1L in transcriptional activation of heterochromatic repeats.
Project description:To identify whether Dot1l or Npm1 were enriched in MERVL directly, we performed Dot1l and Npm1 ChIP-seq in wildtype ESCs. We conclude that Dot1l and Npm1 binding were enriched on MERVL-int region, suggesting a direct regulatory role of Dot1l and Npm1 on MERVL expression.
Project description:DOT1L, the only H3K79 methyltransferase in human cells and a homolog of the yeast Dot1, normally forms a complex with AF10, AF17 and ENL/AF9, is dysregulated in most of the cases of mixed lineage leukemia (MLL) and is believed to regulate transcriptional elongation without much evidence. Here we show that the depletion of DOT1L reduced the global occupancy without affecting the traveling ratio or the elongation rate of Pol II, suggesting it not a major player in elongation. An examination of general transcription factors (GTFs) binding revealed globally reduced TBP and TFIIA occupancies near promoters after DOT1L loss, pointing to a role in transcriptional initiation. Proteomic studies uncovered that DOT1L regulates transcriptional initiation likely by facilitating the recruitment of TFIID. Moreover, we found that ENL also regulates transcriptional initiation and that DOT1L stimulates H2B monoubiquitination by limiting the recruitment of human SAGA complex. These results advanced current understanding of epigenetic regulation of transcriptional initiation and roles of DOT1L complex in MLL.
Project description:Spermatogonial stem cells undergo both self-renewal to maintain the stem cell population and differentiation to produce mature sperm. These processes are controlled by both stem cell-intrinsic and external niche factors. DOT1L, the sole H3K79 methyltransferase, is dispensable for mouse embryonic stem cell self-renewal but instead functions as a barrier to somatic cell reprogramming. Here we show that DOT1L is required for spermatogonial stem cell self-renewal. Mice lacking DOT1L in the germ cells show a failure in the maintenance of spermatogonial stem cells without a block in spermatogenic cell differentiation and thus a progressive loss of germ cells, leading to a Sertoli-cell-only syndrome. Chemical inhibition of DOT1L in cultured stem cells reduces the spermatogonial stem cell activity after transplantation. RNA-seq analysis reveals downregulation of Hoxc cluster genes in DOT1L-inhibited spermatogonia stem cells. Single cell RNA-seq analysis demonstrates that inhibition of DOT1L sequesters spermatogonial stem cells in a primitive state and prevents them from transitioning to a progenitor state. These results identify a new function for DOT1L in adult stem cells and provides a paradigm for regulation of spermatogonial stem cell self-renewal. Self-renewal of spermatogonial stem cells is vital to life-long production of male gametes and thus fertility. However, the underlying mechanisms remain enigmatic. Here, we show that DOT1L, the sole H3K79 methyltransferase, is required for spermatogonial stem cell self-renewal. Mice lacking DOT1L fail to maintain spermatogonial stem cells, characterized by a sequential loss of germ cells from spermatogonia to spermatids and ultimately a Sertoli-cell-only syndrome. Inhibition of DOT1L reduces the stem cell activity after transplantation, prevents spermatogonial stem cells from transitioning to a progenitor state, and sequesters them in a primitive state. Furthermore, DOT1L promotes expression of the fate-determining HoxC transcription factors in spermatogonial stem cells. Our findings identify an essential function for DOT1L in adult stem cells and provide an epigenetic paradigm for regulation of spermatogonial stem cells.
Project description:Osteoclasts are absorptive cells and play a critical role in homeostatic bone remodeling and pathological bone resorption. Emerging evidence suggests an important role for epigenetic regulation of osteoclastogenesis. In this study, we investigated the role of DOT1L, which regulates gene expression epigenetically by histone H3K79 methylation during osteoclast formation. DOT1L and H3K79me2 levels were upregulated during osteoclast differentiation. Small molecule inhibitor- (EPZ5676 or EPZ004777) or short hairpin RNA-mediated reduction in DOT1L expression promoted osteoclast differentiation and resorption. DOT1L inhibition also increased osteoclast area and accelerated bone mass reduction in a mouse ovariectomy (OVX) model of osteoporosis. DOT1L inhibitors did not alter osteoblast differentiation in vitro and in vivo. Proteomics data, together with bioinformatics analysis, revealed that DOT1L inhibition altered reactive oxygen species (ROS) generation, autophagy activation, and cell fusion-related protein expression. ROS generation increased, and autophagy activation and cell migration ability enhancement were verified subsequently by flow cytometry and transwell migration assays. DOT1L inhibition increased NFATc1 nuclear translocation and NF-κB activation and strengthend osteoclast fusion and expression of resorption-related protein CD9, and MMP9 in osteoclasts derived from RAW264.7. Our findings support a new mechanism of DOT1L-mediated H3K79me2 epigenetic regulation of osteoclast differentiation, implicating DOT1L as a new therapeutic target for osteoclast dysregulation-induced disease.