Regulation of Gene Expression by Dietary Fat

描述（由申请人提供）：饮食中脂肪的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，摄入大部分热量作为脂肪会导致胰岛素抵抗和II型糖尿病的发展。关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作用如何影响细胞核中的事件，人们知之甚少。在我们研究脂肪酸调节基因表达的机制的过程中，我们发现RNA剪接的速率在肝脏和原代肝细胞中分别被膳食多不饱和脂肪和花生四烯酸抑制。使用葡萄糖-6-磷酸脱氢酶（G6 PD）酶，缺乏转录调控，作为一个独特的模型，我们已经产生了一个原型，将这些发现扩展到其他基因。由于超过60%的基因经历选择性剪接，并且许多基因还受到剪接效率变化的调节，因此这些发现对于确定整个发育过程中细胞内和多种细胞类型中表达的蛋白质具有广泛的意义。本申请的中心假设是，受调控剪接的基因在外显子中含有剪接调控区。这些区域含有并置的剪接沉默和增强元件。剪接抑制蛋白与沉默子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。G6 PD基因外显子12的剪接调控区是我们进行这些研究的范例。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，我们将确定细胞内的信号转导途径，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，本实验将为剪接酶的调控提供新的数据，并确定营养素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，摄入大部分热量作为脂肪会导致胰岛素抵抗和II型糖尿病的发展。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。该项目将提供有关膳食脂肪调节细胞内代谢方式的重要新数据。

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.