ADAPTIVE REGULATION IN 3T3-L1 ADIPOCYTES

在过去的十年中，取得了重大进展，包括 我们对葡萄糖转运过程的理解，通常是限速 参与葡萄糖代谢。在此期间最重要的两个发现 时期包括作为基础的移位机制 胰岛素刺激的葡萄糖转运与多发性硬化的鉴定 异构体。分解代谢抑制(适应性调节)有 在原核生物中被广泛研究，并被认为是一种重要的 全球监管体系。尽管如此，真核生物的营养控制 直到最近才接受调查，很少有研究集中在 完全依赖于葡萄糖转运蛋白。与3T3-LL脂肪细胞共培养 LINE作为脂肪的模型，我们将探索对 构成葡萄糖转运蛋白，Glut 1。这项提案的目标是 定义通过以下方面的变化来管理传输的机制 葡萄糖可获得性。这一目标将通过解决 遵循特定的目标。首先，我们将描述增强的“基本” 转运活动作为葡萄糖饥饿的函数。我们将测试 假设活性增强是由于Glut 1蛋白升高所致， 在翻译层面上进行监管。其次，我们将定义 饥饿诱导运输下调的机制。我们将测试 假设葡萄糖通过一种途径抑制转运活动 使用代谢抑制剂的蛋白质合成不依赖机制， 亚细胞分离和免疫检测。最后，我们将定义 葡萄糖调节蛋白GRP 78与GLUT 1的关系。 这些独特的研究将检验GRP78延缓过剩1的假设 当转运蛋白被不适当地糖基化时的处理。这将是 通过分析GRP 78和GLUT 1在 葡萄糖缺乏的细胞。总之，这些研究将确定这些机制 脂肪细胞独有的，它可能在体内发挥作用，调节组织结构 对循环中的血糖波动作出反应的运输。

Within the last ten years, significant progress has been made which extends our understanding of the glucose transport process, often the rate-limiting step in glucose metabolism. The two most important discoveries during this period include the translocation mechanism which underlies insulin-stimulated glucose transport and the identification of multiple isoforms. Catabolite repression of metabolism (adaptive regulation) has been widely studied in procaryotes and is recognized as an important and global regulatory system. Despite this, nutrient control in eucaryotes has been under investigation only recently with few studies focusing exclusively on the glucose transporter. With the 3T3-Ll adipocyte cell line as a model for adipose, we will explore the regulation of the constitutive glucose transporter, GLUT 1. The objective of this proposal is to define the mechanisms by which transport is regulated by changes in glucose availability. This objective will be met by addressing the following Specific Aims. First, we will characterize the enhanced 'basal' transport activity as a function of glucose starvation. We will test the hypothesis that enhanced activity is due to elevated GLUT 1 protein, regulated at the translational level. Secondly, we will define the mechanism of down-regulation of starvation-induced transport. We will test the hypothesis that glucose represses transport activity by a protein-synthesis independent mechanism using metabolic inhibitors, subcellular fractionation, and immunodetection. Finally, we will define the relationship between the glucose-regulated protein, GRP 78, and GLUT 1. These unique studies will test the hypothesis that GRP 78 retards GLUT 1 processing when the transporter is inappropriately glycosylated. This will be accomplished by analyzing co-precipitation of GRP 78 and GLUT 1 in glucose-deprived cells. Together, these studies will define the mechanisms unique to adipocytes which may act in vivo to regulate constitutive transport in response to fluctuations in circulating glucose.