Signaling Pathways Regulating the Activity of ChREBP by Glucose

描述（由申请人提供）：项目概述拟议项目的总体目标是更好地了解调节成熟动物脂肪储存的细胞内和细胞外信号。从进化的角度来看，生物体在资源丰富时以脂肪形式储存能量的能力对于其在随后资源稀缺时的生存至关重要。然而，不适当的脂肪储存会导致人类多种代谢问题，包括常见的疾病，如肥胖和2型糖尿病，以及罕见的疾病，如脂肪代谢障碍。碳水化合物反应元件结合蛋白（ChREBP）是最近被鉴定为在碳水化合物转化为脂肪中起关键作用的蛋白质。该因子通过激活脂质合成和储存的细胞程序来响应血清葡萄糖水平的变化，缺乏ChREBP的小鼠表现出脂质和葡萄糖代谢的显著改变。AMP依赖性蛋白激酶（AMPK）是另一种特征明确的蛋白质，可感知细胞内能量和葡萄糖，但似乎以与ChREBP相反的方式发挥作用。我们和其他人以前曾报道过，常用的糖尿病药物二甲双胍依赖于AMPK发挥其对血糖的有益作用。我们希望检验AMPK作为ChREBP的负调节剂发挥直接或间接作用以及葡萄糖摄取升高降低AMPK活性从而规避负调节的假设。本项目的目的是首先确定血清葡萄糖变化诱导的ChREBP的特异性修饰，然后研究这些修饰是否与AMPK的已知活性一致。这些修改将被识别使用质谱技术，一个新兴的技术，我们的实验室已经证明的专业知识。我们还将测试增强或抑制AMPK活性的条件是否会导致细胞内ChREBP的功能变化。然后，我们将测试AMPK功能的遗传破坏，无论是在培养细胞还是在小鼠中，是否会导致ChREBP活性的变化。相关性2型糖尿病和肥胖是日益增长的公共卫生问题，其特征都是脂肪代谢紊乱。控制脂肪合成和储存的特定分子的鉴定将为这些疾病提供新的见解，并可能产生新的治疗药理学靶点。

DESCRIPTION (provided by applicant): Project Summary The overarching goal of the proposed project is to better understand the intracellular and extracellular signals that regulate fat storage in the mature animal. From an evolutionary perspective, the ability of an organism to store energy in the form of fat when resources are plentiful is critical for its survival in ensuing times when resources are scarce. However, inappropriate fat storage can lead to multiple metabolic problems in man, including both common diseases such as obesity and type 2 diabetes as well as rarer disorders such as the lipodystrophies. The carbohydrate response-element binding protein (ChREBP) is a protein recently identified as playing a critical role in conversion of carbohydrate into fats. This factor responds to changes in serum glucose levels by activating cellular programs of lipid synthesis and storage, and mice lacking ChREBP exhibit significant alterations in lipid and glucose metabolism. AMP-dependent protein kinase (AMPK) is another well-characterized protein that senses intracellular energy and glucose but appears to function in a manner opposite to ChREBP. We and others have previously reported that the commonly used diabetes medication metformin relies on AMPK for exerting its beneficial effect on blood glucose. We wish to test the hypothesis that AMPK plays either a direct or indirect role as a negative regulator of ChREBP and that elevation in glucose uptake reduces AMPK activity and thus circumvents the negative regulation. The aims of this proposed project are to first identify the specific modifications on ChREBP induced by changes in serum glucose and then to investigate whether these modifications are consistent with the known activity of AMPK. These modifications will be identified using the technique of mass spectrometry, an emerging technology with which our laboratory has proven expertise. We also will test whether conditions that either enhance or inhibit AMPK activity lead to functional changes in ChREBP within the cell. We will then test whether genetic disruption of AMPK function, both in cultured cells as well as in mice, leads to changes in ChREBP activity. Relevance Type 2 diabetes and obesity are growing public health concerns both characterized by disordered fat metabolism. Identification of the specific molecules controlling fat synthesis and storage will provide new insights into these disorders and may potentially produce novel pharmacologic targets for treatment.