Novel Pathways for Triglyceride Storage and Adipogenesis

脂肪组织在脂质代谢和维持能量平衡中起着核心作用。 脂肪细胞发育或功能的失调有助于代谢性疾病的发病机制 包括肥胖、糖尿病和动脉粥样硬化。本项目的长期目标是了解 控制脂肪细胞分化和功能的分子途径，这是整个 这是PPG的主题。最终，这些途径的阐明预计将概述新的机会， 人类代谢疾病的治疗干预。 第一个具体目标是确定参与甘油三酯的新转录因子的功能 存储.我们利用高通量筛选方法来鉴定刺激脂质过氧化的新基因， 脂肪形成的细胞培养模型中的积累。我们最初的重点将是TLE 3，一个转录 辅阻遏物，以前没有公认的链接到脂质代谢。TLE 3优先表达于 在肥胖/糖尿病的鼠模型中上调，在脂肪营养不良的小鼠模型中下调。 Lipinl-/-小鼠。我们推测TLE 3通过直接调节脂肪细胞基因表达发挥作用， 并且TLE 3活性的改变可能导致胰岛素抵抗和/或肥胖。我们建议：（a） 鉴定TLE 3的靶基因，（B）以检验TLE 3作为脂肪调节的辅因子的假设 转录因子，（c）确定TLE 3在体内代谢中的作用，和（d）检验假设 TLE 3和lipins在控制脂肪细胞基因表达中起协同作用。 第二个具体目的是确定小分子调节剂的作用机制， 脂肪生成我们已经利用高通量筛选来鉴定新的小分子脂质诱导剂， 积累，包括一种化合物，骆驼蓬碱，调节整个PPARy/lipin的表达， 体内1/GPIHBP 1轴。此外，去氢骆驼蓬碱在小鼠中具有抗糖尿病活性，验证了我们的方法作为 新的策略，为鉴定药理学调节剂的代谢。我们假设， 小分子改变脂肪形成程序的分子机制将导致识别 新的信号通路。我们建议：（a）绘制介导小分子活性的顺式作用元件， （B）鉴定小分子对脂肪形成作用的介质，（c）测试 PPARy表达的小分子调节剂包含一类新的药理学调节剂的假设 体内脂质和葡萄糖代谢的调节剂，（d）确定骆驼蓬碱调节的机制 GPIHBP 1表达，以及（e）检查Aim 1中阐明的转录途径之间的串扰 和Aim 2中表征的小分子信号传导途径。

Adipose tissue plays a central role in lipid metabolism and the maintenance of energy homeostasis. Dysregulation of adipocyte development or function contributes to the pathogenesis of metabolic diseases including obesity, diabetes and atherosclerosis. The long-term goal of this Project is to understand the molecular pathways that control adipocyte differentiation and function, a goal which central to the overall theme of this PPG. Ultimately, elucidation of such pathways is expected to outline new opportunities for therapeutic intervention in human metabolic disease. The first Specific Aim is to define the function of novel transcription factors involved in triglyceride storage. We have utilized a high throughput screening approach to identify new genes that stimulate lipid accumulation in cell culture models of adipogenesis. Our initial focus will be on TLE3, a transcriptional corepressor with no previously recognized link to lipid metabolism. TLE3 is preferentially expressed in adipose tissue, is upregulated in murine models of obesity/diabetes, and is downregulated in lipodystrophic Lipinl-/- mice. We hypothesize that TLE3 acts through the direct regulation of adipocyte gene expression and that alterations in TLE3 activity may contribute to insulin resistance and/or obesity. We propose: (a) to identify target genes for TLE3, (b) to test the hypothesis that TLE3 serves as a cofactor for adipomodulatory transcription factors, (c) to determine the role of TLE3 in metabolism in vivo, and (d) to test the hypothesis that TLE3 and lipins cooperate in the control of adipocyte gene expression. The second Specific Aim is to identify the mechanism of action of small molecule regulators of adipogenesis. We have utilized high throughput screening to identify new small molecule inducers of lipid accumulation, including one compound, harmine, that regulates expression of the entire PPARy/lipin- 1/GPIHBP1 axis in vivo. Moreover, harmine has anti-diabetic activity in mice, validating our approach as a new strategy for the identification pharamcologic regulators of metabolism. We hypothesize that defining the molecular mechanism by which small molecules alter the adipogenic program will lead to the identification of new signaling pathways. We propose to: (a) map the cis-acting elements that mediate the activity of small molecules on the PPARy promoter, (b) identify mediators of small molecule action on adipogenesis, (c) test the hypothesis that small molecule regulators of PPARy expression comprise a novel class of pharmacologic regulators of lipid and glucose metabolism in vivo, (d) determine the mechanism whereby harmine regulates GPIHBP1 expression, and (e) to examine crosstalk between transcriptional pathways elucidated in Aim 1 and small molecule signaling pathways characterized in Aim 2.