Regulation of Cytoplasmic Lipid Droplet Mobilization in Intestinal Enterocyte

大多数哺乳动物将膳食脂肪作为其主要能量来源。肠道中膳食脂肪的处理在全身能量平衡和生理学中起着至关重要的作用，对身体的其他部位和整个系统产生深远的影响。我对NSERC资助的研究项目的长期愿景是定义管理肠道脂质处理的调节机制，并确定它们如何与系统生物学相结合。膳食脂肪被消化并被肠道吸收细胞（肠上皮细胞）吸收。在肠上皮细胞中，大多数吸收的脂肪被包装成脂蛋白颗粒，从细胞分泌出来，为身体提供能量。一部分膳食脂肪在肠上皮细胞中形成细胞质脂滴（CLD）。CLD是具有多种生物学功能的细胞内细胞器，其异常与细胞应激有关。CLD通过脂解被动员以释放脂肪酸，所述脂肪酸被引导至脂蛋白分泌或其他必需的细胞功能。能够控制CLD动员和分配脂肪酸之间的各种生物需求是必不可少的，以维持局部和全身功能。然而，到目前为止，很少有人知道的CLD动员和代谢命运的调控在肠道肠上皮细胞。在这个为期5年的NSERC资助的项目中，我的短期目标是系统地识别和表征肠道肠细胞中脂质代谢的分子介质。我计划利用我在肠道脂质代谢方面的专业知识和我最近的发现，使用创新和综合方法，1）检查CLD动力学，2）鉴定介导CLD动员的蛋白质和磷脂，3）阐明调节CLD动员的蛋白质的功能作用。实验将在我成功建立的动物模型中进行。CLD将通过成像进行分析。将使用蛋白质组学和脂质组学分析整个肠细胞、细胞内细胞器（CLD、内质网）和分泌产物中的蛋白质和磷脂。候选和新鉴定的蛋白质的作用将在体内用蛋白质抑制剂进行检查。该计划提供了尖端的HQP培训机会，以及丰富的知识环境，以提高我们对生物系统基本方面的理解。这些研究的结果不仅将揭示脂质是如何在多种细胞功能中被运输和分配的，而且还将为减轻细胞压力提供机会。考虑到现代社会面临的营养和环境压力，这种知识的进步可能有助于开发新的应对策略，并改善哺乳动物的整体健康。

Most mammals use dietary fats as their major energy source. Handling of dietary fats in the gut plays crucial roles in whole-body energy homeostasis and physiology, with far-reaching impacts on other parts of the body and the overall system. My long-term vision for an NSERC-funded research program is to define the regulatory mechanisms that govern lipid handling in the gut and to determine how they are integrated with systemic biology. Dietary fats are digested and taken up by gut absorptive cells (enterocytes). In the enterocyte, the majority of absorbed fats are packaged into lipoprotein particles that are secreted from the cells to deliver energy to the body. A portion of the dietary fats form cytoplasmic lipid droplets (CLDs) in the enterocytes. CLDs are intracellular organelles that have diverse biological functions, abnormalities of which are linked to cellular stresses. CLDs are mobilized through lipolysis to release fatty acids that are directed to lipoprotein secretion or other essential cellular functions. Being able to control CLD mobilization and to partition fatty acids among various biological needs is essential for maintaining both local and systemic functions. However, to date, very little is known about the regulation of CLD mobilization and metabolic fates in gut enterocytes. My short-term goal during this 5-year NSERC-funded program is to systemically identify and characterize molecular mediators of lipid metabolism in gut enterocytes. I plan to build upon my strong expertise in gut lipid metabolism and my most recent findings, using innovative and integrative approaches, to 1) examine CLD dynamics, 2) identify proteins and phospholipids that mediate CLD mobilization, and 3) elucidate the functional roles of proteins that regulate CLD mobilization. Experiments will be carried out in an animal model I have successfully established. CLDs will be analyzed with imaging. Proteins and phospholipids in whole enterocytes, intracellular organelles (CLDs, endoplasmic reticulum), and secreted products will be analyzed with proteomics and lipidomics. The role of candidate and newly identified proteins will be examined in vivo with protein inhibitors. This program offers cutting-edge HQP training opportunities, as well as enriching intellectual environment for making discoveries that improve our understanding of a fundamental aspect of biological system. Findings from these studies will not only reveal how lipids are trafficked and partitioned among multiple cellular functions, but also open opportunities for mitigating cellular stresses. Considering the nutritional and environmental stresses faced by modern society, such advancements in knowledge may help develop novel coping strategies and improve the overall wellbeing of mammalian life.