Epigenetic Regulation of Adipogenesis

脂肪生成的表观遗传调控

• 批准号: 8349932
• 负责人: Kai Ge
• 金额: $ 58.72万
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8349932
• 关键词: Acetylation; Biological Assay; CCAAT-Enhancer-Binding Protein-alpha; Cell Differentiation process; Cells; Defect; Disease; Ectopic Expression; Enzymes; Epigenetic Process; Fatty acid glycerol esters; Functional RNA; Gene Activation; Gene Expression; Generations; Genes; Histone Acetylation; Histone H3; Histones; Ligands; Lipodystrophy; Lysine; Methylation; Methyltransferase; Non-Insulin-Dependent Diabetes Mellitus; Nuclear Receptors; Obesity; PPAR gamma; Phase; Play; Regulation; Role; Signal Transduction; Site; activating transcription factor; beta catenin; chromatin remodeling; gene repression; histone acetyltransferase; histone modification; inhibitor/antagonist; lipid biosynthesis; member; mutant; prevent; promoter; transcription factor

Specific Aim 1: examine the change of histone modifications on PPARgamma promoter in the early phase of adipogenesis. By ChIP assays, we have observed robust change of multiple histone acetylation and methylation on PPARgamma promoter in the early phase of adipogenesis. Specific Aim 2: investigate the functional significance of the histone modification change on PPARgamma promoter by depleting the responsible enzymes.We show recently that histone H3K27 methyltransferase Ezh2 represses Wnt genes to facilitate adipogenesis. Specifically, we show Ezh2 and its H3K27 methyltransferase activity are required for adipogenesis. Ezh2 directly represses Wnt1, -6, -10a, and -10b genes in preadipocytes and during adipogenesis. Deletion of Ezh2 eliminates H3K27me3 on Wnt promoters and derepresses Wnt expression, which leads to activation of Wnt/beta-catenin signaling and inhibition of adipogenesis. Ectopic expression of the wild-type (WT) Ezh2, but not the enzymatically inactive F667I mutant, prevents the loss of H3K27me3 and the defects in adipogenesis in Ezh2(-/-) preadipocytes. The adipogenesis defects in Ezh2(-/-) cells can be rescued by expression of adipogenic transcription factors PPARgamma, C/EBPalpha, or inhibitors of Wnt/beta-catenin signaling. Interestingly, Ezh2(-/-) cells show marked increase of H3K27 acetylation globally as well as on Wnt promoters. These results indicate that H3K27 methyltransferase Ezh2 directly represses Wnt genes to facilitate adipogenesis and suggest that acetylation and trimethylation on H3K27 play opposing roles in regulating Wnt expression (Wang L. et al., Proc Natl Acad Sci U S A (107): 7317-22, 2010). Specific Aim 3: investigate the roles of other epigenetic mechanisms, in particular chromatin remodeling and non-coding RNAs, in regulation of PPARgamma expression and adipogenesis.

具体目标1：检查在脂肪生成的早期阶段，对PPARGAMMA启动子的组蛋白修饰的变化。通过CHIP分析，我们已经观察到在脂肪生成的早期阶段，多种组蛋白乙酰化和甲基化对ppargamma启动子的稳健变化。 具体目标2：研究组蛋白修饰变化对PPARGAMMA启动子的功能意义。我们最近表明，组蛋白H3K27甲基转移酶EZH2抑制WNT基因以促进脂肪生成。具体而言，我们表明EZH2及其H3K27甲基转移酶活性是脂肪形成所必需的。 EZH2直接抑制前膜细胞和脂肪形成期间的Wnt1，-6，-10a和-10b基因。 EZH2的缺失消除了Wnt启动子上的H3K27Me3和Wnt表达，这导致Wnt/beta-catenin信号传导激活并抑制脂肪形成。野生型（WT）EZH2的异位表达，但不能防止酶非活性F667i突变体，可以防止H3K27me3的损失和EZH2（ - / - ）preadipocytes中脂肪形成的缺陷。 EZH2（ - / - ）细胞中的脂肪形成缺陷可以通过表达脂肪生成转录因子PPARGAMMA，C/EBPALPHA或WNT/beta-catenin信号传导的抑制剂来挽救。有趣的是，EZH2（ - / - ）细胞在全球和WNT启动子上显示出H3K27乙酰化的明显增加。这些结果表明，H3K27甲基转移酶EZH2直接抑制Wnt基因以促进脂肪生成，并表明H3K27对H3K27的乙酰化和三甲基化在调节Wnt表达中起着相反的作用（Wang L.等，Proc Natl Acad Sci U S（107）：7317-22，2010年）。 具体目标3：研究其他表观遗传机制的作用，特别是染色质重塑和非编码RNA，在调节ppargamma表达和脂肪形成中的作用。