Understanding the regulation of ER GPATs to control glycerolipid synthesis in disease

项目总结 细胞依赖于脂肪酸来生成细胞膜和储存能量。在细胞内， 脂肪酸通过一系列代谢酶结合到细胞膜上并储存甘油脂。这个 这一过程对人类健康和疾病的重要性突出表现为许多代谢性疾病 以功能失调的脂肪堆积为特征。尽管从脂肪合成甘油脂很重要 酸性细胞动态平衡与人类疾病，对变构机制知之甚少 对这一过程进行调控。 使用CRISPR基因筛查和无偏向脂质组学，Birsoy实验室最近发现了钙调神经磷酸酶B 同源蛋白1(CHP1)作为内质网(ER)甘油脂合成的新调节因子。在这 我们实验室最近发表的一项研究表明，CHP1的缺失严重阻碍了脂肪酸的结合和储存 在哺乳动物细胞和无脊椎动物模型生物中。从机制上讲，我们的实验室证明了CHP1控制 激活甘油脂起始限速酶ER GPAT、GPAT4合成甘油脂 急诊室内的综合。CHP1激活GPAT4的机制是直接的，因为已经发现CHP1 与GPAT4形成络合物。这项工作确定CHP1是为数不多的甘油脂合成调节蛋白之一。 到目前为止所描述的。我们认为，可能存在其他控制脂代谢的调节机制。 这项建议旨在更深入地理解我们在前期工作中发现的新生物学和 发现ER GPAT活性和功能的其他调节因子。在目标1中，我们试图理解 CHP1结合和激活GPAT4的机制。这将提供对翻译后 调节脂类代谢，并指导未来研究类似CHP1的其他机制。在目标2中，我们将 利用我们最近建立的一种新的小鼠模型，在体内研究ER GPAT在体内的动态平衡和 像NASH这样的疾病。在目标3中，我们试图确定管理ER驻地GPAT4的其他机制 通过无偏见的基因筛选和蛋白质组学方法。从基础生物化学到小鼠 建模，该应用程序将解决细胞新陈代谢中突出的基本问题，并理解 这一生物学背景下的复杂疾病正在折磨着人类。本研究提出的创新性研究 申请除了个性化的培训计划外，还将提供严格的博士后培训，为 让我成为一名独立调查员。

PROJECT SUMMARY Cells are dependent on fatty acids for the generation of membranes and the storage of energy. Within the cell, fatty acids incorporate into membrane and storage glycerolipids through a series of metabolic enzymes. The importance of this process to human health and disease is highlighted by the fact that many metabolic diseases are characterized by dysfunctional lipid accumulation. Despite the importance of glycerolipid synthesis from fatty acids cellular homeostasis and human disease, relatively little is known about the allosteric mechanisms that regulate and control this process. Using CRISPR genetic screens and unbiased lipidomics, the Birsoy lab recently identified calcineurin B homologous protein 1 (CHP1) as a novel regulator of endoplasmic reticulum (ER) glycerolipid synthesis. In this recently published study, our lab showed that loss off CHP1 severely blunted fatty acid incorporation and storage in mammalian cells and invertebrate model organisms. Mechanistically, our lab demonstrated that CHP1 controls glycerolipid synthesis by activating the ER GPAT, GPAT4, the initial rate limiting enzyme for glycerolipid synthesis within the ER. The mechanism by which CHP1 activates GPAT4 is direct, as it was found that CHP1 and GPAT4 form a complex. This work identified CHP1 as one of few regulatory proteins of glycerolipid synthesis described to date. We believe other such regulatory mechanisms control lipid metabolism likely exist. This proposal seeks to more deeply understand the novel biology discovered in our preliminary work and discover additional regulators of ER GPAT activity and function. In Aim 1, we seek to understand the precise mechanism by which CHP1 binds and activates GPAT4. This will provide insight into the posttranslational regulation of lipid metabolism and guide future study of other mechanisms analogous to CHP1. In Aim 2, we will utilize a novel mouse model we recently generated to study ER GPAT function in vivo in both homeostasis and disease such as NASH. In Aim 3, we seek to identify additional mechanisms regulating ER resident GPAT4 through unbiased genetic screening and proteomic approaches. Spanning basic biochemistry to mouse modeling, this application will address outstanding fundamental questions in cellular metabolism and understand this biology in the context of complex diseases afflicting humankind. The innovative studies proposed in this application in addition to the personalized training plan, will provide rigorous postdoctoral training that will prepare me to become an independent investigator.