Regulation of Gene Expression by Dietary Fat

描述（由申请人提供）：饮食中脂肪的数量和类型一直是公共卫生建议的主题，以预防肥胖、糖尿病和动脉粥样硬化。大量的文献表明，摄入大量的脂肪会导致胰岛素抵抗和II型糖尿病。对于膳食脂肪摄入的非病理性波动如何改变细胞内代谢以及这些信号传导作用如何影响细胞核中的事件，我们知之甚少。在我们对脂肪酸调控基因表达机制的研究过程中，我们发现，在肝脏和原代肝细胞中，多不饱和脂肪和花生四烯酸分别抑制了RNA剪接率。利用缺乏转录调控的葡萄糖-6-磷酸脱氢酶（G6PD）作为一个独特的模型，我们已经产生了一个将这些发现扩展到其他基因的原型。由于超过60%的基因经历选择性剪接，许多基因也受剪接效率变化的调节，这些发现将对确定整个发育过程和多种细胞类型中细胞内表达的蛋白质具有广泛的意义。该应用的中心假设是剪接受调控的基因在外显子中包含剪接调控区域。这些区域包含并置拼接、沉默和增强元素。剪接抑制蛋白与消声器的结合排除了剪接激活蛋白与增强子的结合。多不饱和脂肪酸通过翻译后修饰和/或核丰度调节剪接调节蛋白的活性。G6PD基因外显子12的剪接调控区是我们这些研究的范例。尽管普遍需要调节剪接，但对调节这一过程的细胞内信号知之甚少。在这些研究的过程中，我们将定义细胞内的信号转导途径，通过这些途径，营养物质和营养状况可以改变剪接调节蛋白的活性或丰度。因此，本实验将提供剪接压力调控的新数据，并确定营养物质调控基因表达的新途径。公共卫生相关性：饮食中脂肪的数量和类型一直是预防肥胖、糖尿病和动脉粥样硬化的公共卫生建议的主题。大量的文献表明，摄入大量的脂肪会导致胰岛素抵抗和II型糖尿病。此外，饮食中脂肪的数量和类型可以调节血清胆固醇和甘油三酯的水平，这是动脉粥样硬化的危险因素。该项目将为膳食脂肪调节细胞内代谢的方式提供重要的新数据。

DESCRIPTION (provided by applicant): The amount and type of fat in the diet has been the subject of public health recommendations to prevent obesity, diabetes and atherosclerosis. A considerable body of literature has developed that suggests that eating the majority of calories as fat results in the development of insulin resistance and type II diabetes mellitus. Much less is known about how non-pathological fluctuations in dietary fat intake alter intracellular metabolism and how these signaling actions affect events in the nucleus. In the course of our studies on mechanisms by which fatty acids regulate gene expression, we discovered that the rate of RNA splicing is inhibited in liver and primary hepatocytes by dietary polyunsaturated fat and by arachidonic acid, respectively. Using the glucose-6-phosphate dehydrogenase (G6PD) enzyme, which lacks transcriptional regulation, as a unique model we have generated a prototype for extending these findings to other genes. Because greater than 60% of genes undergo alternative splicing and many are also regulated by changes in splicing efficiency, these findings will have widespread signficance for determining the proteins expressed within cells throughout development and in muliple cell types. The central hypothesis of this application is that genes that under regulated splicing comtain splicing regulatory regions in an exon. These regions contain juxtaposed splicing silencing and enhancing elements. The binding of splicing inhibitory proteins to the silencer exclude the binding of splicing activators proteins to the enhancer. Polyunsaturated fatty acids regulate the activity of the splicing regulatory proteins by posttranslational modification and/or nuclear abundance. The splicing regulatory region of exon 12 of the G6PD gene is our paradigm for these studies. Despite the ubiquitous need for regulated splicing, little is known about the intracellular signals regulating this process. In the course of these studies, we will define intracellular signal transduction pathways by which nutrients and nutritional status can alter the activity or abundance of splicing regulatory proteins. Thus, the experiments in the current proposal will provide new data on regulation of splicing pre se and define a new pathway by which nutrients regulate gene expression. PUBLIC HEALTH RELEVANCE: The amount and type of fat in the diet has been the subject of public health recommendations to prevent obesity, diabetes and atherosclerosis. A considerable body of literature has developed that suggests that eating the majority of calories as fat results in the development of insulin resistance and type II diabetes mellitus. In addition, the amount and type of fat in the diet can regulate the levels of serum cholesterol and triglycerides, risk factors for atherosclerosis. This project will provide important new data on the ways in which dietary fat can regulate intracellular metabolism.