Lipid Metabolism in Fat Cells

肥胖是一个主要的健康问题，易患2型糖尿病和其他严重疾病。一个更 全面了解脂肪细胞中脂肪合成如何调节对于指导合理的 开发治疗肥胖及其并发症的新方法。在上一个资助期，我们 证明中链脂肪酸（辛酸）刺激β-氧化和抑制甘油三酯 在脂肪细胞中的合成，模仿禁食的一些代谢作用。类似的抗脂肪生成作用 已经在用TNF α处理的脂肪细胞中发现。我们证明了三种压力源，禁食 体内、辛酸和体外TNF α诱导许多相同的细胞应答。这些包括 活性氧化物质（ROS）的产生增加，MAP-激酶（MARK）和AMP- 活化的蛋白激酶（AMPK）和核转录因子PPARgamma的表达降低 和相关的脂肪生成基因。根据这些发现，我们计划使用这三个压力源来操纵 脂肪细胞中的脂肪生成来剖析调节机制。我们假设关键信号（ROS或 ROS非依赖性）是β-氧化增加的结果。 应激反应激酶，其抑制PPARgamma，减弱脂肪必需基因的表达， 合成.为了验证这一假设，我们提出了以下具体目标：（1）确定ROS是否是 对调节脂肪生成至关重要;（2）测试β-氧化的变化是否产生关键信号， 导致PPARgamma失活;和（3）确定PPARgamma是否是信号 收敛，控制应激诱导的抗脂肪生成作用，什么是PPARgamma的机制 失活，以及哪些代谢基因对胁迫操作最敏感。每个目标都将是 细胞生物学和分子生物学的综合应用， 结合代谢和生物化学方法，使用培养鼠和人脂肪细胞作为 以及啮齿动物模型。总之，这些研究将为压力诱导的调节提供新的见解。 脂肪细胞中的脂肪生成，调节能量平衡的潜在重要途径。

Obesity is a major health problem that predisposes to type 2 diabetes and other serious conditions. A more complete understanding of how fat synthesis is regulated in adipocytes is critical to guide rational development of new approaches for treating obesity and its complications. In the last grant period, we demonstrated that medium-chain fatty acids (octanoate) stimulate beta-oxidation and inhibit triglyceride synthesis in adipocytes, mimicking some of the metabolic effects of fasting. Analogous anti-lipogenic effects have been found in adipocytes treated with TNFalpha. We demonstrated that the three stressors,fasting in vivo, octanoate, and TNFalpha in vitro, induce many of the same cellular responses. These include increased generation of reactive oxidative species (ROS), activation of MAP-kinases (MARK) and AMP- activated protein kinase (AMPK), and decreased expression of the nuclear transcription factor PPARgamma and associated lipogenic genes. In light of these findings, we plan to use these three stressorsto manipulate lipogenesis in adipocytes to dissect mechanisms of regulation. We hypothesize that critical signals (ROS or ROS-independent) are generatedas a result of increased beta-oxidation.These signaling molecules activate stress-responsive kinases, which inactivate PPARgamma,attenuating expression of genes necessary for fat synthesis. To test this hypothesis, we propose the following specific aims: (1) to determine whether ROS is crucial for regulation of lipogenesis; (2) to test if changes in beta-oxidation generate critical signals that cause inactivation of PPARgamma; and (3) to determine if PPARgamma is the point at which signals converge that control stress-induced anti-lipogenic effects, what is the mechanism of PPARgamma inactivation, and which metabolic genes are most sensitive to the stress manipulation. Each aim will be addressed with comprehensive and integratedapplication of cell biology and molecular biology in combination with metabolic and biochemical approaches, using culture murine and human adipocytes as well as rodent models. Together, these studies will provide new insights into the stress-induced regulation of lipogenesis in adipocytes, a potentially important avenue for modulating energy balance.