Developmental Regulation of Cytoplasmic Lipid Droplet Synthesis

细胞质脂滴合成的发育调控

• 批准号: 8511744
• 负责人: Steven M Anderson
• 金额: $ 18.65万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8511744
• 关键词: AKT1 gene; Acyl Coenzyme A; Adenoviruses; Adipose tissue; Affect; Alveolar; Apical; Binding; Biochemical; Calories; Capsid Proteins; Cell Culture Techniques; Cell membrane; Cells; Complex; Data; Defect; Development; Dissection; Doctor of Philosophy; Endoplasmic Reticulum; Enzymes; Epithelial Cells; Essential Fatty Acids; Failure; Goals; Growth; Hormones; Human; Impairment; Infant; Instruction; Knockout Mice; Knowledge; Laboratories; Lactation; Lipase; Lipids; Lipolysis; Liquid substance; Mammary gland; Mediating; Membrane; MicroRNAs; Milk; Modeling; Molecular; Mus; Mutation; Neonatal; Newborn Infant; Nutritional; Organ; Phase; Physiological; Play; Pregnancy; Process; Production; Property; Proteins; Publishing; Reaction; Regulation; Research Design; Role; Signal Pathway; Signal Transduction; Signaling Molecule; Surface; System; Techniques; Testing; Tissues; Transgenic Mice; Transgenic Organisms; Triglyceride Metabolism; Triglycerides; adipophilin; base; density; diacylglycerol O-acyltransferase; lipid metabolism; mammary gland development; meetings; membrane synthesis; mutant; nutrition; promoter; research study

Milk is a complex fluid capable of sustaining the total nutrition of the human infant for 6 months or longer. To meet the caloric and nutritional demands of newborns, mammary epithelial cells synthesize and secrete large quantifies of triglyceride (TAG) into milk during lactation. Milk lipids originate from protein-coated triglyceride droplets (CLD), which are synthesized at the endoplasmic reticulum (ER) and transported to the apical plasma membrane where they are secreted by a unique membrane envelopment process. Several lines of evidence indicate that CLD production by milk secreting cells is developmentally regulated, and that it is induced during differentiation of the mammary gland into a secretory organ by sequential activation of processes that inhibit TAG lipolysis and stimulate TAG synthesis. Disruption of CLD induction has significant physiological consequences including impaired glandular development and lactation failure. The long-term objectives of our laboratory are to elucidate the molecular and cellular mechanisms underlying regulation CLD development in differentiating milk secreting cells, and how impairment of CLD development interferes with mammary gland differentiation. Our studies indicate that TAG lipolysis is mediated by adipose triglyceride lipase (ATGL), and that inhibition of ATGL lipolysis by the CLD coat protein adipophilin (ADPH) is responsible for initiating CLD production during the initial phase of mammary gland differentiation. Subsequent CLD accumulation is hypothesized to depend on AKTI dependent activation of TAG synthesis through a mechanism that involves modulation of the activity of acyl-CoA:diacylglycerol acyltransferase-1 (DGAT1), the enzyme responsible for synthesizing TAG. We propose to test these hypotheses by determining the specific contributions of ADPH inhibition of TAG lipolysis and DGAT1 dependent TAG synthesis to CLD development in the differentiating mouse mammary gland, and to define the specific physiological roles of AKTI activity in regulating this process. Because lipid synthesis in the mammary gland is robust and developmentally regulated by well defined promoter systems, and mammary epithelial cells can be manipulated by transgenic and adenoviral techniques, the proposed studies offer an excellent opportunity to understand molecular interactions involved in TAG synthesis and storage that may have applicability in other cells and tissues. RELEVANCE (See instructions): Milk lipids, mainly triglcyerides, supply the majority of the calories for neonatal growth and the essential fatty acids needed for neonatal membrane synthesis and the synthesis of bioactive lipid signalling molecules. Disrupting mammary gland triglyceride metabolism impairs milk lipid precursor formation and inhibits glandular differentiation producing lactation failure. This proposal focuses on understanding how milk lipid formation is regulated and the role of this process in mammary aland development.

牛奶是一种复杂的液体，能够维持人类婴儿6个月或更长时间的全部营养。到 满足新生儿的热量和营养需求，乳腺上皮细胞合成和分泌 在泌乳期间，大量甘油三酯（TAG）进入乳汁。牛奶脂质来源于蛋白质涂层 甘油三酯液滴（CLD），其在内质网（ER）处合成并运输至 它们通过独特的膜分泌过程分泌到顶端质膜。几 一系列证据表明，乳汁分泌细胞产生CLD是发育调节的， 它是在乳腺分化为分泌器官的过程中，通过连续激活 抑制TAG脂解和刺激TAG合成的过程。CLD诱导的中断具有显著的 生理后果，包括腺体发育受损和泌乳失败。长期 我们实验室的目标是阐明调控的分子和细胞机制 CLD在分化的乳汁分泌细胞中的发展，以及CLD发展的损害如何干扰 乳腺分化。我们的研究表明TAG脂解是由脂肪介导的， 甘油三酯脂肪酶（ATGL），且CLD外壳蛋白亲脂蛋白（ADPH）对ATGL脂解抑制作用是 负责在乳腺分化的初始阶段启动CLD产生。 假设随后的CLD蓄积依赖于TAG合成的AKTI依赖性激活 通过调节酰基辅酶A：二酰基甘油酰基转移酶-1的活性 （DGAT 1），负责合成TAG的酶。我们建议通过以下方式来检验这些假设： 确定ADPH抑制TAG脂解和DGAT 1依赖性TAG的特异性贡献 在分化中的小鼠乳腺中CLD发育的特异性合成，并定义特异性的 AKTI活性在调节这一过程中的生理作用。因为乳腺中的脂质合成 是稳健的，并由明确的启动子系统进行发育调控，乳腺上皮细胞可以 通过转基因和腺病毒技术操作，拟议的研究提供了一个极好的机会， 了解TAG合成和储存中涉及的分子相互作用， 其他细胞和组织。 相关性（参见说明）： 乳脂质，主要是甘油三酯，提供新生儿生长所需的大部分热量， 新生儿膜合成和生物活性脂质信号分子合成所需的酸。 破坏乳腺甘油三酯代谢会损害乳脂质前体的形成， 腺体分化导致泌乳失败。这项建议的重点是了解如何牛奶脂质 的形成是受调节的，这一过程在乳腺和发育中的作用。