Spatial determinants in lipid metabolic organization at the sub-organelle level

项目总结/摘要 为了适应代谢信号和生存压力，如营养饥饿，细胞储存高- 能量脂质在专门的细胞器称为脂滴（LDs），出现在 内质网（ER），细胞的代谢中心。最近的研究表明， LD在细胞生理学中起着许多作用，但它们如何在功能上标记为 具体任务不明确。事实上，ER网络本身执行许多蜂窝网络。 功能，但这种功能的多样性是如何实现机械尚不清楚。的 这项资助的目的是剖析LD的分子机制， ER网络在亚细胞器水平上实现功能多样性。资本化 根据已发表的和初步的数据，我们发现LD具有独特的表面蛋白质组 其为单细胞内的LD提供功能特异性。此外，我们发现， 细胞器间接触位点定义了ER子域，在细胞器中具有特定的作用。 甲羟戊酸代谢的区室化。在这里，我概述了三个方向， 使LD和ER功能区室化的机制解剖成为可能： 1)在方向1，我们将利用酵母遗传学，生物化学和代谢 解剖以解剖酵母ER-溶酶体如何接触（称为核-泡 连接，NVJ）作为ER亚结构域和“代谢平台”， 划分甲羟戊酸代谢，促进代谢重塑 在葡萄糖饥饿期间。 2)在方向2，我们将利用一个大规模的屏幕来剖析LD是如何 用特定的蛋白质标记，使细胞内的独特作用。 3)在方向3中，我们将利用最先进的冷冻FIB-SEM成像来解剖如何 LD内的脂质相变选择性地重塑LD表面蛋白质组，并且 最终影响LD功能和LD细胞器间接触部位。 总的来说，这些方向将提供深入了解新的细胞组织 使LD和ER网络能够实现功能划分的原则， 劳动他们还将表征甾醇的脂质相变特性， 促进肥胖症、心脏病和动脉粥样硬化的疾病病理。

Project Summary/Abstract To adapt to metabolic cues and survive stresses like nutrient starvation, cells store high- energy lipids in specialized organelles called lipid droplets (LDs) that emerge from the endoplasmic reticulum (ER), the metabolic center of cells. Recent studies reveal that LDs serve many roles in cell physiology, but how they are functionally ear-marked for specific tasks is unclear. Indeed, the ER network itself executes numerous cellular functions, but how this functional diversity is mechanistically achieved is unclear. The purpose of this grant is to dissect the molecular mechanisms by which LDs and the ER network achieve functional diversity at the sub-organelle level. Capitalizing on published and preliminary data, we find that LDs exhibit unique surface proteomes that provide functional specificity for LDs within single cells. Furthermore, we find that inter-organelle contact sites define ER sub-domains with specific roles in the compartmentalization of mevalonate metabolism. Here, I outline three directions that enable the mechanistic dissection of LD and ER functional compartmentalization: 1) In direction 1, we will leverage yeast genetics, biochemistry, and metabolic dissection to dissect how yeast ER-lysosome contacts (called nucleus-vacuole junctions, NVJs) serve as ER sub-domains and “metabolic platforms” that spatially compartmentalize mevalonate metabolism, and promote metabolic remodeling during glucose starvation. 2) In direction 2, we will capitalize on a large-scale screen to dissect how LDs are labeled with specific proteins to enable unique roles within cells. 3) In direction 3, we will utilize state-of-the-art cryo-FIB-SEM imaging to dissect how lipid phase transitions within LDs selectively remodel the LD surface proteome, and ultimately influence LD function and LD inter-organelle contact sites. Collectively, these directions will provide insights into new cellular organizational principles that enable to LDs and the ER network to achieve a functional division-of- labor. They will also characterize lipid phase transition properties of sterols, which promote disease pathologies in obesity, heart disease, and atherosclerosis.