Regulation of P450c17 Lyase Activity in Adrenache

肾上腺素中 P450c17 裂解酶活性的调节

• 批准号: 6669423
• 负责人: QING DONG
• 金额: $ 12.18万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-30 至 2008-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6669423
• 关键词: Escherichia coli; SDS polyacrylamide gel electrophoresis; adrenal glands; complementary DNA; cytochrome P450; dehydroepiandrosterone; enzyme activity; gonads; hormone biosynthesis; hormone regulation /control mechanism; lyase; oxidoreductase; phosphoprotein phosphatase; phosphorylation; polycystic ovary syndrome; polymerase chain reaction; pregnenolone; protein kinase; steroid 7alpha hydroxylase; thin layer chromatography; transfection; western blottings; yeast two hybrid system

DESCRIPTION (provided by applicant): Adrenarche is the peri-pubertal event that occurs when the human adrenal begins to make large amounts of 19-carbon androgen precursors, especially dehydroepiandrosterone (DHEA). Children normally begin adrenarche at about age 8-9, before the onset of puberty. Clinical studies show that early, exaggerated adrenarche may be an early sign of the polycystic ovary syndrome (PCOS), which affects 3-5% of women of reproductive age. PCOS women have increased secretion of C-19 steroids from both the adrenals and ovaries. The conversion of 17OH pregnenolone to DHEA by the 17,20 lyase activity of cytochrome P450c17 determines the amount of C-19 steroid produced in both tissues. P450c17 catalyzes both 17a-hydroxylase and 17,20 lyase activities. When expressed in the zona fasciculata, P450c17 catalyzes 17(t-hydroxylase but very little 17,20 lyase activity to produce cortisol. When it is expressed in the adrenal zona reticularis and in the gonad, it has high 17,20 lyase activity and catalyzes the formation of DHEA. The ratio of hydroxylase to lyase activities is not constant, but is regulated at the post-translational level, at least in part by serine/threonine phosphorylation. Phosphorylation of P450c17 preferentially increases lyase activity. Dephosphorylation of P450c17 by protein phosphatase PP2A inhibits lyase activity without affecting 17a-hydroxylase activity. Thus, I hypothesize that the phosphorylation by protein kinase and dephosphorylation by protein phosphatase of P450c17 are two physiologically important pathways in regulating human adrenal androgen production. I propose to test this hypothesis by pursuing four specific aims. Aim 1: Identify the specific phosphorylated serine and threonine residues on P450c17 critical for 17,20 lyase activity. Aim 2: Determine whether phosphorylation of serine residues influences association with P450 oxidoreductase and/or cytochrome b5. Aim 3: Identify the kinase(s) responsible for P450c17 phosphorylation. Aim 4: Define the regulatory subunit(s) of phosphatase PP2A responsible for dephosphorylation of P450c17. Fulfillment of these four aims will expand our understanding of the mechanisms by which androgen production is regulated in both health and disease and should provide novel insights into the mechanisms by which the adrenals and gonads of women with PCOS overproduce androgens.

描述（由申请人提供）： 肾上腺素是当人肾上腺开始制造大量19碳雄激素前体，尤其是脱氢表雄酮（DHEA）时发生的肾上腺周期事件。儿童通常在青春期发作之前大约在8-9岁左右开始肾上腺素。临床研究表明，早期，夸张的肾上腺素结构可能是多囊卵巢综合征（PCOS）的早期迹象，这会影响3-5％的生殖年龄妇女。 PCOS妇女增加了肾上腺和卵巢中C-19的类固醇的分泌。通过17,20个细胞色素P450C17的17,20裂解酶活性，将17OH妊娠的转化为DHEA决定了两种组织中产生的C-19类固醇的量。 P450C17催化17A-羟化酶和17,20个裂解酶活性。 When expressed in the zona fasciculata, P450c17 catalyzes 17(t-hydroxylase but very little 17,20 lyase activity to produce cortisol. When it is expressed in the adrenal zona reticularis and in the gonad, it has high 17,20 lyase activity and catalyzes the formation of DHEA. The ratio of hydroxylase to lyase activities is not constant, but is regulated at the翻译后，至少部分是由丝氨酸/苏氨酸磷酸化的，P450C17的磷酸化优先增加了裂解液的活性。 p450c17的蛋白质磷酸酶是调节人肾上腺雄激素产生的两个重要途径。 /或细胞色素B5。 PCOS过量生产雄激素的妇女的肾上腺肾上腺和性腺的机制。