HORMONAL REGULATION OF PHOSPHOINOSITIDE METABOLISM

磷脂酰肌醇代谢的激素调节

• 批准号: 3235638
• 负责人: JOHN N FAIN
• 金额: $ 14.01万
• 依托单位: UNIVERSITY OF TENNESSEE HEALTH SCI CTR
• 依托单位国家: 美国
• 财政年份: 1985
• 资助国家: 美国
• 起止时间: 1985-09-01 至 1991-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3235638
• 关键词: adenosine diphosphate; adenosinetriphosphatase; affinity labeling; alpha adrenergic agent; alpha adrenergic receptor; aluminum; autoradiography; bacterial toxins; binding proteins; calcium transporting ATPase; cell free system; cholera toxin; enterotoxins; enzyme induction /repression; fluorine; gel electrophoresis; glycosylation; guanine nucleotides; guanosinetriphosphatases; high performance liquid chromatography; hormone receptor; hormone regulation /control mechanism; ion exchange chromatography; laboratory mouse; laboratory rabbit; laboratory rat; lipid metabolism; liver cells; liver metabolism; magnesium; membrane proteins; pertussis; phosphatidylinositols; phospholipase C; phospholipids; radiotracer; tissue /cell culture; vasopressins

The aim of these studies is to examine the hormonal regulation of phosphoinositide metabolism in rat hepatocytes and other cells. In liver, alpha-1 catecholamines and vasopressin activate glycogen phosphorylase secondary to an elevation of intracellular calcium and diacylglycerol. The rise in calcium is secondary to formation of inositol 1,4,5 trisphosphate derived from phospholipase C-induced breakdown of phosphatidylinositol 4,5- bisphosphate (PIP2) as is diacylglycerol. It is now clear that phospholipase C activity is regulated by guanine nucleotides. This project focuses on the role of guanine nucleotides in hormone induced breakdown of phosphatidyl-inositol 4,5- bisphosphate. Our long-term goal is isolation of the membrane bound phospholipase C responsible for breakdown of phosphoinositides. The requirement for guanine nucleotides suggests that a guanine nucleotide binding protein, tentatively called Np, may be involved in coupling of hormone-receptor complexes to phospholipase C. Phospholipase C activity will be examined using tritiated PIP2. We will attempt to label Np with GTP analogues and find a toxin that will ADP-ribosylate it, with the eventual aim of isolating this putative guanine nucleotide binding protein. Investigations will continue on the regulation by agonists that stimulate polyphosphoinositide breakdown, of high affinity GTPase activity in hepatocytes and other cell types. We intend to establish the identity of the guanine nucleotide binding protein involved. The inhibition by vasopressin of hepatocyte (Ca2+ Mg2+) ATPase activity will be further investigated in an attempt to elucidate the link, if any, between this effect and phosphoinositide breakdown. This project is primarily a metabolic investigation using biochemical techniques. The studies are done in experimental animals and should provide significant insights into various diseases of metabolism and especially diabetes.

这些研究的目的是检查荷尔蒙调节 大鼠肝细胞及其他细胞中磷酸肌醇代谢的影响 细胞。 在肝脏中，α-1 儿茶酚胺和加压素激活 继发于细胞内糖原磷酸化酶升高 钙和二酰甘油。 钙的升高是继发于 形成肌醇 1,4,5 三磷酸衍生自 磷脂酶 C 诱导的磷脂酰肌醇 4,5- 分解 二磷酸酯 (PIP2) 和二酰甘油一样。 现在已经清楚的是 磷脂酶 C 的活性受鸟嘌呤核苷酸调节。 该项目重点研究鸟嘌呤核苷酸在 激素诱导的磷脂酰肌醇 4,5- 分解 二磷酸盐。 我们的长期目标是膜的隔离 结合磷脂酶 C 负责分解 磷酸肌醇。 鸟嘌呤核苷酸的需要量 表明鸟嘌呤核苷酸结合蛋白暂时 称为 Np，可能参与激素受体的偶联 与磷脂酶 C 形成复合物。磷脂酶 C 的活性将为 使用氚化PIP2进行检查。 我们将尝试用 GTP 类似物并找到一种毒素，可以将其 ADP 核糖基化， 分离这种假定的鸟嘌呤核苷酸的最终目标 结合蛋白。 监管部门将继续调查 刺激多磷酸肌醇分解的激动剂，高 肝细胞和其他细胞类型中的亲和力 GTP 酶活性。 我们 打算确定鸟嘌呤核苷酸结合的身份 涉及蛋白质。 加压素对肝细胞的抑制作用 (Ca2+ Mg2+) ATPase 活性将在 尝试阐明这种效应与 磷酸肌醇分解。 该项目主要是一个 使用生化技术进行代谢研究。 这 研究是在实验动物中进行的，并且应该提供 对各种代谢疾病的重要见解 尤其是糖尿病。