DEVELOPMENTAL REGULATION OF CYTOPLASMIC LIPID DROPLET SYNTHESIS

细胞质脂滴合成的发育调控

• 批准号: 7018032
• 负责人: James Lewis McManaman
• 金额: $ 23.42万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2010-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7018032
• 关键词: cell component structure /function; cholesterol esters; cytoplasm; endoplasmic reticulum; enzyme activity; gene expression; genetic models; genetically modified animals; hormone regulation /control mechanism; laboratory mouse; lipid biosynthesis; lipids; mammary epithelium; model design /development; organ culture; polymerase chain reaction; pregnancy; protein protein interaction; reproductive development; triglycerides

In mammary epithelial cells cytoplasmic lipid droplets that are formed and secreted into milk provide essential fatty acids and cholesterol for membrane synthesis and a large percentage of neonatal calories. Since the mammary gland is one of the most active lipogenic organs of the body it provides an ideal model system to understand the cellular and molecular processes involved in lipid droplet formation. The overall goal of this project is to define how lipids, triglycerides and cholesterol esters, synthesized in the endoplasmic reticulum, are packaged into cytoplasmic lipid droplets. The PAT family (Perilipin, Adipophilin, TIP47) of lipid droplet associated proteins and caveolins have been shown to play an essential role in the formation, stabilization and metabolism of lipid droplets in other tissues. In the mammary gland this process is developmentally coordinated and regulated by the hormones of pregnancy. We hypothesize that the endoplasmic reticulum of mammary alveolar epithelial cells undergoes structural alterations during pregnancy resulting in the formation of specific lipid droplet assembly domains that contain the enzymes of lipid synthesis as well as the proteins necessary for lipid droplet assembly. In Specific Aim 1 we use morphological techniques to define the temporal alterations in the structure of the endoplasmic reticulum during lipid droplet formation. These changes will be correlated with expression of lipid synthetic enzymes and lipid synthesis in Specific Aim 2. The expression levels of candidate genes will be altered in Specific Aim 3 to develop a precise molecular model for the interactions of proteins involved in formation of lipid droplets. These experiments are designed to identify the structural and biochemical processes involved in formation of lipid droplets and to provide a framework for understanding the role of hormones in this process. The unique aspect of this proposal is the hypothesis that CLD form within specialized domains in the ER containing all the synthetic machinery. If this hypothesis is correct it will substantially alter our current understanding of the cell biological mechanisms involved in the initiation of CLD formation.

在乳腺上皮细胞中，形成并分泌到牛奶中的细胞质脂质液滴为膜合成提供必需的脂肪酸和胆固醇，并提供很大一部分新生儿卡路里的卡路里。由于乳腺是人体最活跃的脂肪源器官之一，因此它提供了理想的模型系统，以了解脂质液滴形成所涉及的细胞和分子过程。该项目的总体目标是定义脂质如何， 在内质网中合成的甘油三酸酯和胆固醇酯被包装成细胞质脂质液滴。脂质液滴相关蛋白和小窝蛋白的PAT家族（Peripin，脂肪素，TIP47）在其他组织中脂质滴的形成，稳定和代谢中起着至关重要的作用。在乳腺中，这个过程在发育中是由怀孕的激素进行了协调和调节的。我们假设乳腺上皮细胞的内质网发生结构改变 在怀孕期间，导致形成了包含脂质合成酶以及脂质液滴组装所需的蛋白质的特定脂质液滴组装结构域。在特定的目标1中，我们使用形态学技术来定义脂质液滴形成过程中内质网的结构的时间变化。这些变化将与特定目标2中脂质合成酶和脂质合成的表达相关。在特定目标3中，候选基因的表达水平将改变，以开发出一种精确的分子模型，以使蛋白质相互作用涉及脂质液滴的形成。这些实验旨在确定与脂质液滴形成有关的结构和生化过程，并提供一个框架，以了解激素在此过程中的作用。该提案的独特方面是假设CLD在ER中包含所有合成机械的专用域中形成。如果该假设是正确的，它将大大改变我们当前对CLD形成涉及的细胞生物学机制的理解。