Development of Secretory Mechanisms During Lactogenesis

这个项目将集中在乳腺上皮细胞从妊娠到哺乳的第二阶段从怀孕到哺乳过程中观察到的胞外和脂肪分泌途径的分子变化。我们的主要假设是，驻留高尔基体和细胞质脂滴(CLD)蛋白的一部分的差异表达和/或翻译后修饰允许高尔基体和细胞质脂滴(CLD)的扩增和CLDs的变化，为广泛的乳蛋白和脂肪分泌做准备。一项无偏见的全球蛋白质组学分析(2D-凝胶电泳法/质谱仪)将在泌乳过程中的多个时间点进行，以确定内源蛋白和新蛋白的差异表达/修饰序列，从而导致高尔基体扩张和脂肪分泌。在从怀孕到哺乳的过渡过程中，将有一组精选的这些蛋白质的功能特征。对一种新的高尔基体基质样蛋白RLP30的初步研究使我们得出了目前的假设，即高尔基体基质的重塑在细胞器扩张中起着至关重要的作用。脂类分泌的机制涉及黄嘌呤氧化还原酶(XOR)、丁咯菲林(Btn)、脂肪细胞分化相关蛋白(ADRP)和膜上相关的硫醇氧化酶之间的相互作用。这些相互作用将在分子和功能水平上进行研究，蛋白质组学将用于鉴定脂质分泌过程的其他成分。这些方法将为未来对乳汁分泌的研究建立基本框架。

This project will focus on the molecular changes in exocytic and lipid secretory pathways observed to be functionally up-regulated during the Stage II transition from pregnancy from pregnancy to lactation in mammary epithelial cells. Our major hypothesis is that differential expression and/or post-translational modifications of a subset of resident of resident Golgi and cytoplasmic lipid droplet (CLD) proteins allow for the amplification of the Golgi and changes in the CLDs in preparation for extensive milk protein and lipid secretion. An unbiased global proteomics analysis (2D-gel electrophoresis/mass spectrometry) will be carried out a multiple time points during lactogenesis to identify the sequence in which endogenous and novel proteins are differentially expressed/modified resulting in Golgi expansion and lipid secretion. A select group of these proteins will be functionally characterized during the transition from pregnancy to lactation. Preliminary studies on RLP30, a novel Golgi matrix-like protein have led us to our current hypothesis that remodeling of the Golgi matrix plays a crucial role in organellar expansion. The mechanism of lipid secretion prosed involves interactions among xanthine oxidoreductase (XOR), butyrophilin (Btn), adipocyte differentiation related protein (ADRP), and a membrane associated thiol-oxidase. These interactions will be investigated at molecular and functional levels and proteomics will be used to identify additional components of the lipid secretion process. These approaches will establish the fundamental framework for future studies of milk secretion.