Project description:Sirt6, the NAD+-dependent deacetylase, has been described to deacetylate H3K9, H3K18, and H3K56. However, analysis of the acetylation status revealed that loss of Sirt6 caused a massive increase of histone H3K56ac levels but no detectable change of histone H3K9ac and H3K18ac, indicating that SIRT6 is the dominant deacetylase for H3K56ac in muscle stem cells (MuSCs). Further, we investigate genome-wide H3K56ac profiling in the absence of Sirt6 in MuSCs and mouse embryonic stem cells (mESCs) using high throughput sequencing (ChIP-seq).
Project description:Sirt6, the NAD+-dependent deacetylase, has been described to deacetylate H3K9, H3K18, and H3K56. However, analysis of the acetylation status revealed that loss of Sirt6 caused a massive increase of histone H3K56ac levels but no detectable change of histone H3K9ac and H3K18ac, indicating that SIRT6 is the dominant deacetylase for H3K56ac in muscle stem cells (MuSCs). Further, we investigate genome-wide H3K56ac profiling in the absence of Sirt6 in MuSCs and mouse embryonic stem cells (mESCs) using high throughput sequencing (ChIP-seq).
Project description:Sirt6, the NAD+-dependent deacetylase, has been described to deacetylate H3K9, H3K18, and H3K56. However, analysis of the acetylation status revealed that loss of Sirt6 caused a massive increase of histone H3K56ac levels but no detectable change of histone H3K9ac and H3K18ac, indicating that SIRT6 is the dominant deacetylase for H3K56ac in muscle stem cells (MuSCs). Further, we investigate genome transposase-accessible chromatin in the absence of Sirt6 in MuSCs using high throughput sequencing (ATAC-seq).
Project description:Chromatin remodeling proteins are frequently dysregulated in human cancer, yet little is known about how they control tumorigenesis. Here, we uncover an epigenetic program mediated by the NAD+-dependent histone deacetylase Sirtuin 6 (SIRT6) that is critical for suppression of pancreatic ductal adenocarcinoma (PDAC), one of the most lethal malignancies. SIRT6 inactivation accelerates PDAC progression and metastasis via upregulation of Lin28b, a negative regulator of the let-7 microRNA. SIRT6 loss results in histone hyperacetylation at the Lin28b promoter, Myc recruitment, and pronounced induction of Lin28b and downstream let-7 target genes, HMGA2, IGF2BP1 and IGF2BP3. This epigenetic program defines a distinct subset representing 30-40% of human PDAC, characterized by poor prognosis and an exquisite dependence on Lin28b for tumor growth. Thus, we identify SIRT6 as an important PDAC tumor suppressor, and uncover the Lin28b pathway as a potential therapeutic target in a molecularlydefined PDAC subset. ChIP-Seq experiments to examine H3K56ac histone modifications in murine PDAC cells that are Sirt6 wild type (WT), Sirt6 knock-out (KO), and Sirt6 KO cells engineered to express Sirt6 WT (Sirt6 KO + Sirt6 WT Restored).
Project description:In this study, Pax7-Cre mediated inactivation of Sirt6 in mdx mice resulted in profound improvement of the mdx phenotype at the functional level. To study the underlying molecular mechanisms we performed RNA-seq of MuSCs from control, mdx and Sirt6mKO/mdx mice.
Project description:Purpose: The complete understanding of how genetic and epigenetic components control beta cell differentiation and function is key to the discovery of novel therapeutic approaches to prevent beta cell dysfunction and failure in the progression of type 2 diabetes. Our goal was to elucidate the role of histone deacetylase SIRT6 in beta-cell development and homeostasis. Methods: The Sirt6 endocrine progenitor cell conditional knockout (EKO) and beta-cell-specific knockout (BKO) mice were generated using the Cre-loxP system. Mice were assayed for islet morphology, glucose tolerance, glucose-stimulated insulin secretion, and susceptibility to streptozotocin. Transcriptional regulatory functions of SIRT6 in primary islets were evaluated by RNA-seq analysis. RT-qPCR and immunoblot were used to verify and investigate the gene expression changes. Chromatin occupancies of SIRT6, H3K9Ac, H3K56Ac, and active RNA Polymerase II were evaluated by chromatin immunoprecipitation. Results: Deletion of Sirt6 in pancreatic endocrine progenitor cells did not affect endocrine morphology, beta cell mass, or insulin production, but did result in glucose intolerance and defective glucose-stimulated insulin secretion in mice. Conditional deletion of Sirt6 in adult beta cells reproduced the insulin secretion defect. Loss of Sirt6 resulted in aberrant upregulation of TXNIP. SIRT6 deficiency led to increased accumulations of H3K9Ac, H3K56Ac, and active RNA polymerase II at the promoter region of Txnip. SIRT6-deficient beta cells exhibited a time-dependent increase of H3K9Ac, H3K56Ac, and TXNIP levels. Furthermore, beta-cell-specific SIRT6 deficient mice showed increased sensitivity to streptozotocin. Conclusions: Our results reveal that SIRT6 suppresses Txnip expression in beta-cells via deacetylation of histone H3 and plays a critical role in maintaining beta-cell function and viability. Agents that preserve SIRT6 activity may be beneficial for preventing the progression of type 2 diabetes.
Project description:Pericentric heterochromatin silencing at mammalian centromeres is essential for mitotic fidelity and genomic stability. Defective pericentric silencing is observed in senescent cells, aging tissues, and mammalian tumors, but the underlying mechanisms and functional consequences of these defects are unclear. Here, we uncover a pivotal role of the human SIRT6 enzyme in pericentric transcriptional silencing, and this function protects against mitotic defects, genomic instability, and cellular senescence. At pericentric heterochromatin, SIRT6 promotes deacetylation of a new substrate, histone H3 lysine K18 (H3K18), and inactivation of SIRT6 in cells leads to H3K18 hyperacetylation and aberrant accumulation of pericentric transcripts. Strikingly, RNAi-depletion of these transcripts rescues the mitotic and senescence phenotypes of SIRT6-deficient cells. Together, our findings reveal a new function for SIRT6 and H3K18Ac regulation at heterochromatin, and demonstrate the pathogenic role of de-regulated pericentric transcription in aging- and cancer- related cellular dysfunction. H3K18ac, H3K9ac, H3K9me3, H3K56ac and Input ChIP-seq for U2OS cell