HORMONAL REGULATION OF PHOSPHOINOSITIDE METABOLISM

磷脂酰肌醇代谢的激素调节

• 批准号: 3235634
• 负责人: JOHN N FAIN
• 金额: $ 14.7万
• 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/3235634
• 关键词: adenosine diphosphate; adenosinetriphosphatase; affinity labeling; alpha adrenergic agent; aluminum; autoradiography; bacterial toxins; cell free system; cholera toxin; enterotoxins; enzyme induction /repression; fluorine; gel electrophoresis; guanine nucleotides; guanosine triphosphate; high performance liquid chromatography; hormone regulation /control mechanism; ion exchange chromatography; lipid metabolism; liver cells; liver metabolism; magnesium; 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激素调节 大鼠肝细胞中的磷酸肌醇代谢和其他 细胞。 在肝脏中，α-1儿茶酚胺和加压素激活 继发于细胞内升高的糖原磷酸化酶 钙和二酰基甘油。 钙的升高是继发的 肌醇1,4,5三磷酸的形成 磷脂酶C诱导的磷脂酰肌醇4,5-的分解 双磷酸（PIP2）和二酰基甘油也是。 现在很明显 磷脂酶C活性受鸟嘌呤核苷酸调节。 该项目着重于鸟嘌呤核苷酸在 激素诱导的磷脂酰肌醇4,5-的分解 双磷酸盐。 我们的长期目标是隔离膜 结合磷脂酶C负责分解 磷酸肌醇。 鸟嘌呤核苷酸的需求 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 磷脂酶C.磷脂酶C活性将是 使用Tritied Pip2检查。 我们将尝试将NP标记 GTP类似物并找到一种将其ADP-核糖基化的毒素，并使用 隔离这种推定的鸟嘌呤核苷酸的最终目的 结合蛋白。 调查将继续对 激动剂刺激高磷酸肌醇分解，高 肝细胞和其他细胞类型中的亲和力GTPase活性。 我们 打算建立鸟嘌呤核苷酸结合的身份 涉及蛋白质。 肝细胞加压素的抑制作用 （Ca2+ Mg2+）ATPase活性将进一步研究 试图在此效果之间阐明链接（如果有） 磷酸肌醇分解。 这个项目主要是 使用生化技术的代谢研究。 这 研究是在实验动物中进行的，应提供 对各种新陈代谢疾病的重要见解和 特别是糖尿病。