Regulation of de novo lipogenesis through BAD-dependent glucose signaling

通过 BAD 依赖性葡萄糖信号传导调节从头脂肪生成

• 批准号: 8897058
• 负责人: Elizabeth Lane
• 金额: $ 3.52万
• 依托单位: HARVARD MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-01 至 2018-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8897058
• 关键词: Acetates; Acetylation; Active Sites; Acute; Affect; BCL2 gene; BH3 Domain; Binding; Binding Proteins; Biochemical; Carbohydrates; Cells; Charge; Cues; DNA Binding; Data; Disease; Enzymes; Equilibrium; Fasting; Fatty acid glycerol esters; Fructosephosphates; Gene Expression; Genes; Genetic; Glucokinase; Gluconeogenesis; Glucose; Glucose-6-Phosphate; Glycogen; Glycolysis; Hepatic; Hepatocyte; Hormonal; Lead; Learning; Link; Lipids; Liver; Measurement; Mediating; Metabolic; Modification; Molecular; Mus; Non-Insulin-Dependent Diabetes Mellitus; Nuclear Translocation; Nutrient; Obesity; Organ; Pathway interactions; Phosphorylation; Post-Translational Protein Processing; Production; Protein Family; Proteins; Regulation; Response Elements; Role; Serine; Signal Transduction; Testing; Vascular Diseases; activating transcription factor; blood glucose regulation; detection of nutrient; extracellular; feeding; glucose metabolism; glucose production; insight; lead-binding proteins; lipid biosynthesis; liquid chromatography mass spectrometry; new therapeutic target; programs; protein activation; public health relevance; reaction rate; response; small hairpin RNA; transcription factor

 DESCRIPTION (provided by applicant): Regulation of de novo lipogenesis through BAD-dependent glucose signaling The homeostatic balance between hepatic utilization, storage, and production of glucose and fat in fed and fasted states is exquisitely controlled by hormonal and nutrient cues. In the fed state, the liver stores excess glucose first as glycogen then as fat through de novo lipogenesis. How the liver senses glucose to determine its utilization and storage is not fully understood at the molecular level. Emerging evidence indicates that glucose-derived metabolites, including the activity of glucokinase (GK), which catalyzes the first step of hepatic glycolysis, influence de novo lipogenesis by both providing metabolic precursors for lipid synthesis as well as triggering the expression of lipogenic genes. Glucose regulation of de novo lipogenesis is dependent, at least in part, on the Carbohydrate Response Element Binding Protein (ChREBP), a transcription factor that is activated by certain glucose-derived metabolites. My proposed studies test the role of the BCL-2 family protein BAD as an upstream regulator of hepatic glucose signaling and de novo lipogenesis through ChREBP. BAD's modulation of glucose metabolism is mediated by phosphorylation of Ser155, which leads to direct activation of GK. The functional relevance of this interaction is evident from the observations that BAD deficiency or interference with its phosphorylation is associated with reduced hepatic GK activity and glycolysis. I have found that glucose induction of ChREBP activity and lipogenic gene expression is diminished in Bad -/- hepatocytes. These data, together with the known capacity of BAD to activate GK and GK's relevance in ChREBP activation, give rise to the hypothesis that BAD modulates hepatic ChREBP activity and de novo lipogenesis through its ability to regulate GK activity. I will test this hypothesis through the following specific aims: Aim 1 will interrogate the acute and cell autonomous effect of BAD modifications in primary hepatocytes and the attendant changes in GK on stimulation of ChREBP transcriptional activity by glucose. Aim 2 will determine the functional and metabolic correlates of BAD-dependent changes in lipogenic gene expression by biochemical measurement of de novo lipogenesis and glucose-dependent changes in lipid profiles in primary hepatocytes following genetic or pharmacologic modification of BAD. Aim 3 will dissect the mechanistic link between BAD modifications and ChREBP activity by examining alterations in defined post translational modifications of ChREBP in response to glucose, including phosphorylation and acetylation known to modulate ChREBP transcriptional activity. In the fullness of time, these studies will provide an integrated picture of the pathway connecting BAD and GK- dependent glucose metabolism with ChREBP activity and the lipogenic program. Understanding this pathway should yield useful molecular insights into hepatic glucose sensing, nutrient utilization and storage.

 描述（通过应用提供）：通过不良依赖性的葡萄糖信号来调节从头脂肪生成，在肝脏利用，储存，储存和产生FED和禁食状态下的葡萄糖和脂肪之间的稳态平衡完全受荷尔蒙和营养线索的控制。在美联储状态下，肝脏储备首先超过葡萄糖作为糖原，然后通过从头脂肪生成作为脂肪。肝脏如何在分子水平上完全了解葡萄糖以确定其利用和储存。新兴的证据表明，葡萄糖衍生的代谢产物，包括葡萄糖酶（GK）的活性，促成肝糖溶解的第一步，都会通过为脂质合成的代谢前体和脂肪生成基因的表达提供代谢前体来影响从头脂肪生成。从头脂肪生成的葡萄糖调节至少部分取决于碳水化合物反应元件结合蛋白（CHREBP），这是一种转录因子，该转录因子被某些葡萄糖衍生的代谢产物激活。我提出的研究测试了Bcl-2家族蛋白不良的作用，这是通过Chrebp通过CHREBP的肝葡萄糖信号传导和从头脂肪形成的上游调节剂。 BAD的调节葡萄糖代谢是由Ser155的磷酸化介导的，Ser155导致GK的直接激活。这种相互作用的功能相关性是从缺乏或干扰其磷酸化的观察结果证明的，与肝脏GK活性降低和糖酵解的降低有关。我发现，在不良 - / - 肝细胞中，Chrebp活性和脂肪生成基因表达的葡萄糖诱导降低。这些数据以及已知的坏能力激活GK和GK在CHREBP激活中的相关性，引起了这样的假设，即不良调节肝素CHREBP活性和从头脂肪生成，其通过调节GK活性的能力。我将通过以下特定目的检验这一假设：AIM 1将询问原发性肝细胞中不良修饰的急性和细胞自主效应，以及GK中随之而来的葡萄糖转录活性刺激CHREBP转录活性的变化。 AIM 2将通过生化测量遗传学或药理学修饰后，通过生化脂肪生成的生化测量和脂质谱的脂质变化，通过生化脂质发生和葡萄糖依赖性变化来确定脂肪生成基因表达的功能和代谢相关性。 AIM 3将通过检查CHREBP对葡萄糖的响应后的定义后翻译后修饰的变化（包括磷酸化和已知可调节CHREBP转录活性的乙酰化）的变化来剖析不良修饰与Chrebp活性之间的机械联系。在时间的饱满状态下，这些研究将提供连接不良和GK依赖性葡萄糖代谢与Chrebp活性和脂肪生成程序的途径的综合图像。了解该途径应产生有用的分子见解，以介入肝葡萄糖感应，养分利用和储存中。