Mechanisms of Lipid Droplet Protein Targeting

项目摘要 细胞代谢能量以中性脂质的形式储存，特别是三酰基甘油（TG），其 包装在细胞质脂滴（LD）中。LD的过度积累发生在 许多疾病，包括肥胖、2型糖尿病、动脉粥样硬化和代谢综合征。此外，LD 在一些感染中起关键作用，包括丙型肝炎病毒和衣原体，通过促进一些复制， 病原体 尽管它们在人类健康和疾病中起着重要作用，但令人惊讶的是，人们对LD的了解甚少。LD包括 被磷脂单层包围的疏水核心。LD的大多数功能，包括TG合成， TG储存和能量动员由这些表面蛋白执行和调节。如何将这些 然而，蛋白质特异性地靶向LD仍然不清楚。在细胞器中，LD是独特的 因为它们的表面在疏水相（LD核）和水相（ 细胞质），因此不能容纳具有球状结构域的典型跨膜蛋白。 因此，蛋白质靶向LD必须涉及独特的机制。 在这个项目中，我们将确定蛋白质是如何特异性地靶向LD表面的。我们将 研究包括GPAT 4和其他甘油三酯酶如何重新定位于LD，使其能够生长。在 此外，我们将确定如何两亲性螺旋含有蛋白质，包括限速 磷脂酰胆碱酶CTP：磷酸胆碱胞苷酰转移酶（CCT），特异性靶向于 从胞质溶胶中分离LD表面以促进扩增。对于项目的每个部分，我们将使用尖端的 生物物理学，生物化学，细胞生物学，蛋白质组学和计算技术，并验证我们的发现， 不同的模型系统，如果蝇和哺乳动物细胞。虽然这里提出的研究是 基本上，确定驱动脂滴蛋白靶向的基本细胞机制将 然而，促进治疗策略的发展，以对抗肥胖症，代谢性疾病， 病毒感染，以及推动进一步研究这些细胞器的细胞生物学。

Project Summary Cellular metabolic energy is stored in the form of neutral lipids, particularly triacylglycerols (TGs), which are packaged in cytoplasmic lipid droplets (LDs). Excessive accumulation of LDs occurs during the progression of many diseases, including obesity, type 2 diabetes, atherosclerosis and metabolic syndrome. In addition, LDs play a key role in some infections, including hepatitis C virus and chlamydia, by facilitating replication of some pathogens. Despite their important role in human health and disease, surprisingly little is known about LDs. LDs consist of a hydrophobic core surrounded by a phospholipid monolayer. Most functions of LDs, including TG synthesis, TG storage, and energy mobilization, are executed and regulated by these surface proteins. How these proteins are specifically targeted to LDs, however, remains unclear. Among organelles, LDs are unique because their surface is at the interface of a hydrophobic phase (the LD core) and an aqueous phase (the cytoplasm) and thus are unable to accommodate typical transmembrane proteins with globular domains. Therefore, the targeting of proteins to LDs must involve unique mechanisms. In this project, we will determine how proteins are specifically targeted to the surface of LDs. We will investigate how triglyceride enzymes including GPAT4 and others re-localize to LDs, enabling their growth. In addition, we will determine how amphipathic helix-containing proteins, including the rate-limiting phosphatidylcholine enzyme CTP:phosphocholine cytidylyltransferase (CCT), are specifically targeted to the surface of LDs from the cytosol to facilitate expansion. For each part of the project, we will use cutting-edge biophysics, biochemistry, cell biology, proteomics and computational techniques and validate our findings in different model systems such as Drosophila and mammalian cells. Although the research proposed here is basic, the determination of the fundamental cellular mechanisms that drives lipid droplet protein targeting will nevertheless facilitate the development of therapeutic strategies to combat obesity, metabolic diseases and viral infections, as well as propel further research into the cell biology of these organelles.