DEHP-INDUCIBLE CYTOCHROME P450 FORMS IN KIDNEY AND LIVER

细胞色素P450 4A(CyP4A)亚家族成员催化omega- 或者是饱和和不饱和脂肪酸的倒数第二次羟基化 前列腺素。P450 4A形式是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 暴露在这些毒剂中。据认为，P450 4A诱导和 氧化脂肪酸的形成可能是诱导 过氧化物酶。有相当大的兴趣在细胞 过氧化物体增殖物的影响，因为这些化学物质已经 可导致啮齿类动物的肝脏肿瘤和睾丸萎缩。在……里面 此外，4A形成合成产物，介导血管收缩。 肾血管和P450介导的脂肪酸omega增加- 羟基酶活性是在血压升高之前报告的。 在基因培育的高血压大鼠身上。P450 4A表格已确定 在许多物种和一个人类中，4A形式已经被测序。在老鼠身上，有三个 4A家族、4A1、4A2和4A3的成员已经被确认并形成 特异性寡核苷酸探针和识别这三种基因的抗体 西方墨迹上的表格已经开发出来了。某些P450 4A表格展示 器官特异性表达，受性激素调节。这个 此次竞争性授权续订的目标是：1)本地化特定的 免疫印迹分析显示，4A在大鼠肾单位的不同节段形成， 因为肾脏的身份还存在相当大的不确定性 表格。将比较男性和男性肾脏4A型的定位。 雌性大鼠因为肾脏4A形式的表达是性激素依赖性的； 2)鉴定由两种免疫抑制药诱导的4A形式， 环孢素和FK 506。环孢素是一种重要的治疗药物 用于移植手术和治疗自身免疫性疾病， 但肾毒性是一个主要的副作用。研究表明，有一种 黄曲霉毒素对脂肪酸欧米伽羟基酶活性诱导的相关性 环孢素与“肾毒性的发病”；3)检查 钙通道阻滞剂抑制肝损伤诱导的机制 邻苯二甲酸二乙基己酯、邻苯二甲酸单乙基己酯中的酶 或氯贝特处理的大鼠或分离的肝细胞，并检查 20-羟基二十碳四烯酸(20-HETE)和其他欧米茄-或倒数第二个- 氧化脂肪酸调节细胞内钙离子浓度 分离大鼠肝细胞；4)检测干扰素诱导的 邻苯二甲酸酯或氯贝特对大鼠肝脏4A形态的抑制作用 分离的肝细胞。干扰素已被证明可以抑制这种诱导 P450 4A构型及其对过氧酶体脂肪酰辅酶A的抑制作用 将检测氧化物酶。这项提议的长期目标是 测定P450介导的脂肪酸欧米伽羟基酶的功能，其 过氧化物酶体增殖中的作用及其在细胞内的生理功能 肾脏。

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.