G protein coupling of lipid metabolism in diabetic heart

G蛋白偶联糖尿病心脏脂质代谢

• 批准号: 6591380
• 负责人: ANTHONY JUSTIN MUSLIN
• 金额: $ 34.15万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2007-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6591380
• 关键词: G protein; beta adrenergic receptor; biological signal transduction; diabetic cardiomyopathy; enzyme induction /repression; fatty acid metabolism; gene targeting; guanosinetriphosphatase activating protein; laboratory mouse; lipid metabolism; peroxisome; phospholipase A2; phospholipase C; second messengers

Both Type I and Type II diabetes are accompanied by a profound switch in myocardial substrate utilization form one which utilizes nearly equal amounts of glucose and fatty acid to a state which predominantly employs FA for substrate. G-proteins in he heart have important effects in mediated the electrical and contractile proteins for myocardium which depend, in part, on an appropriate membrane microenvironment to carry out their specific functions. In the diabetic state profound changes in lipid synthesis occur including alterations in phosphatidylinositol (to which Gq is coupled through phospholipase C leading to IP3 generation) and in the content of plasmalogen which have dramatic effects on membrane fluidity and dynamics. During the last fie years substantial evidence has been accrued demonstrating the altered activity and function of the G-protein axis in diabetic myocardium. These include decreases in beta adrenergic receptor number, increases in Gq-protein mass, altered G-protein receptor-effector coupling, increases in PKCepsilon activity and changes in intracellular calcium ion homeostasis. Thus, it seems likely that altered G signaling contributes to, or underlies the propagation of the pathophysiology manifest in the diabetic heart. The primary hypothesis of Project 4 is that diabetic cardiomyopathy develops as a result of abnormal stimulation of Gq and Gi protein- mediated signaling pathways that leads to alterations in intracellular phospholipases, peroxisomal lipid metabolism and lipid second messenger generation. In order to test this model of diabetic cardiomyopathy we will evaluate the functional and biochemical sequelae of increased or decreased G protein-mediated signal transduction in diabetic murine myocardium. In particular, we will determine whether reduced Gq and Gi signaling in the heart inhibits the development of cardiomyopathy in diabetic mice. G protein signaling will be attenuated by use of RGS4, a GTPase activating protein for Gq and Gi family members. The identify of the specific G protein involved will be determined by targeted disruption of individual Galpha subunit genes. In addition, we will evaluate whether increased Gq signaling potentiates the development of diabetic cardiomyopathy. Furthermore, we will determine whether Gq or Gi signal transduction in heart promotes PLA2 activation and changes in lipid metabolism. Finally, we will examine the transduction in heart promotes PLA2 activation and changes in lipid metabolism. Finally, we will examine the physiological role of the sarcolemmal phospholipase cPLA2gamma, in the pathogenesis of diabetic cardiomyopathy and we will determine whether G protein-mediated signaling regulates activation of this phospholipase.

I型和II型糖尿病都伴随着心肌底物利用形式的深刻开关，该开关将几乎相等的葡萄糖和脂肪酸使用到主要利用FA的底物的状态。他心脏中的G蛋白在介导的心肌的电和收缩蛋白中具有重要作用，这部分取决于适当的膜微环境以执行其特定功能。在糖尿病状态下，脂质合成的深刻变化包括磷脂酰肌醇的改变（GQ通过磷脂酶C偶联，导致IP3产生）以及对膜流动性和动态学产生巨大作用的血浆原成剂的含量。在过去的几年中，大量证据证明了G蛋白轴在糖尿病心肌中的活性和功能改变。这些包括β肾上腺素能受体数量的降低，GQ蛋白质质量增加，G蛋白受体效应器偶联改变，PKCepsilon活性的增加以及细胞内钙离子稳态的变化。因此，改变的G信号传导似乎有助于或构成病理生理学在糖尿病心脏中表现出来的传播。项目4的主要假设是，糖尿病心肌病由于对GQ和GI蛋白介导的信号传导途径的异常刺激而发展，从而导致细胞内磷脂酶，过氧化物酶体脂质代谢代谢和Lipid Second Messenger Generation改变。为了测试这种糖尿病心肌病模型，我们将评估糖尿病鼠心肌中G蛋白介导的信号转导增加或减少的功能和生化后遗症。特别是，我们将确定心脏中的GQ和GI信号降低是否抑制糖尿病小鼠心肌病的发展。 G蛋白信号传导将通过使用RGS4（用于GQ和GI家族成员的GTPase激活蛋白质的RGS4）减弱。涉及特定G蛋白的识别将由靶向单个Galpha亚基基因的靶向破坏确定。此外，我们将评估GQ信号的增加是否增强了糖尿病心肌病的发展。此外，我们将确定心脏中的GQ或GI信号转导能否促进PLA2激活和脂质代谢的变化。最后，我们将检查心脏的转导促进PLA2激活和脂质代谢的变化。最后，我们将研究肌膜磷脂酶CPLA2GAMMA的生理作用，在糖尿病心肌病的发病机理中，我们将确定G蛋白介导的信号是否调节这种磷脂酶的激活。