DEHP-INDUCIBLE CYTOCHROME P450 FORMS IN KIDNEY AND LIVER

DEHP 诱导的细胞色素 P450 在肾脏和肝脏中的形式

• 批准号: 2153429
• 负责人: Richard T. Okita
• 金额: $ 15.37万
• 依托单位: WASHINGTON STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-08-01 至 1998-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2153429
• 关键词: FK506; RNase protection assay; calcium channel blockers; cytochrome P450; diethylhexylphthalate; drug adverse effect; enzyme induction /repression; fatty acid metabolism; gene expression; high performance liquid chromatography; hydroxylation; immunosuppressive; kidney metabolism; kidney pharmacology; laboratory rabbit; laboratory rat; liver metabolism; liver pharmacology; membrane lipids; northern blottings; nuclear runoff assay; peroxidation; phospholipids; scintillation counter; western blottings

Members of the cytochrome P450 4A (CYP4A) subfamily catalyze the omega - or penultimate -hydroxylation of saturated and unsaturated fatty acids and prostaglandins. P450 4A forms are induced by peroxisome proliferators and their induction represents one of the earliest cellular events following exposure to these agents. It is thought that P450 4A induction and formation of oxidized fatty acids may be essential for induction of peroxisomal enzymes. There is considerable interest in the cellular effects of peroxisome proliferators, because these chemicals have been shown to cause hepatic tumors and testicular atrophy in rodents. In addition, 4A forms synthesize products which mediate vasoconstriction of renal vessels and an increase in P450-mediated fatty acid omega- hydroxylase activity is reported prior to the elevation in blood pressure in genetically-bred hypertensive rats. P450 4A forms have been identified in many species and one human 4A form has been sequenced. In rats, three members of the 4A family, 4A1, 4A2, and 4A3 have been identified and form specific oligonucleotide probes and an antibody which recognizes the three forms on western blots have been developed. Certain P450 4A forms exhibit organ specific expression and are regulated by sex hormones. The objectives of this competitive grant renewal are: 1) To localize specific 4A forms in distinct segments of the rat nephron by western blot analysis, because there is considerable uncertainty over the identity of renal forms. The localization of renal 4A forms will be compared in male and female rats because expression of renal 4A forms is sex hormone-dependent; 2) To identify 4A forms which are induced by two immunosuppressive drugs, cyclosporine and FK 506. Cyclosporine is an important therapeutic agent used in transplantation surgery and in treatment of autoimmune diseases, but nephrotoxicity is a major side effect. Studies indicate there is a correlation between induction of fatty acid omega-hydroxylase activity by cyclosporine and "the onset of nephrotoxicity; 3) To examine the mechanisms by which calcium channel blockers suppress induction of hepatic enzymes in DEHP (diethylhexyl phthalate), MEHP (monoethylhexyl phthalate) or clofibrate treated rats or isolated hepatocytes and to examine whether 20-hydroxyeicosatetraenoic acid (20-HETE) and other omega- or penultimate- oxidized fatty acids regulate intracellular calcium concentrations in isolated rat hepatocytes; and 4) To examine the interferon-induced suppression of hepatic 4A forms in phthalate or clofibrate treated rats or isolated hepatocytes. Interferon has been shown to inhibit the induction of P450 4A forms and its suppressive effects on peroxisome fatty acyl CoA oxidase will be examined. The long-term goals of this proposal are to determine the function of P450-mediated fatty acid omega-hydroxylases, its role in peroxisome proliferation, and its physiological function in the kidney.

细胞色素P450 4A（CYP4A）亚家族的成员催化欧米茄 - 或饱和脂肪酸和不饱和脂肪酸的倒数第二羟基化以及 前列腺素。 P450 4A形式由过氧化物酶体增殖物和 它们的诱导代表了以下最早的细胞事件之一 暴露于这些代理商。人们认为P450 4A诱导和 氧化脂肪酸的形成对于诱导可能是必不可少的 过氧化物酶体酶。 细胞引起了极大的兴趣 过氧化物酶体增殖物的作用，因为这些化学物质已经 证明会导致啮齿动物的肝肿瘤和睾丸萎缩。在 另外，4A形成合成产品，介导血管收缩的 肾血管和P450介导的脂肪酸omega-的增加 在血压升高之前，羟化酶活性报道 在遗传性的高血压大鼠中。已经确定了P450 4A表格 在许多物种中，已经对人类4a形式进行了测序。在老鼠中，三个 已经确定并形成了4A家族的成员，4A1、4A2和4A3 特定的寡核苷酸探针和一种识别三种的抗体 已经开发了蛋白质印迹的形式。某些P450 4A表格展示 器官特异性表达，受性激素调节。这 此竞争性授予的目标的目标是：1）本地定位特定的 4A通过蛋白质印迹分析以大鼠肾单位的不同段形式形式， 因为肾脏的身份存在很大的不确定性 表格。将在男性和 雌性大鼠是因为肾脏4a形式的表达是性激素依赖性的。 2）识别由两种免疫抑制药物诱导的4A形式， 环孢素和FK506。环孢菌素是重要的治疗剂 用于移植手术和治疗自身免疫性疾病， 但是肾毒性是主要的副作用。研究表明有一个 通过脂肪酸omega-羟化酶活性诱导的相关性 环孢菌素和“肾毒性的发作； 3）检查 钙通道阻滞剂抑制肝的诱导的机制 DEHP中的酶（苯基己基二乙酸），MEHP（邻苯二甲酸酯） 或锁紧治疗的大鼠或孤立的肝细胞，并检查是否 20-羟基羟基乙烯烯酸（20-HETE）和其他欧米茄或倒数第二 氧化脂肪酸调节细胞内钙浓度 孤立的大鼠肝细胞； 4）检查干扰素诱导的 抑制邻苯二甲酸甲酯或锁紧治疗的大鼠肝4A形式或 孤立的肝细胞。干扰素已显示可抑制诱导 P450 4A形式及其对过氧化物酶体脂肪酰基COA的抑制作用 将检查氧化酶。该提议的长期目标是 确定P450介导的脂肪酸欧米茄羟基酶的功能，ITS 在过氧化物酶体增殖中的作用及其生理功能在 肾。