ANDROGEN PRODUCTION IN ADRENARCHE AND PCOS

肾上腺初现和多囊卵巢综合征中雄激素的产生

• 批准号: 6873053
• 负责人: WALTER L. MILLER
• 金额: $ 34.09万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2007-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6873053
• 关键词: androgens; cholesterol; corticosteroids; cortisol; cytochrome P450; dehydroepiandrosterone; enzyme activity; gel mobility shift assay; gene expression; genetic regulation; genetic transcription; lyase; phosphorylation; polycystic ovary syndrome; polymerase chain reaction; posttranslational modifications; steroid 17alpha monooxygenase; steroid biosynthesis; steroid hormone biosynthesis; threonine; tissue /cell culture; western blottings

Adrenarche is the peri-pubertal event when the human adrenal begins to make large amounts of 19-carbon steroids, especially dehydroepiandrosterone (DHEA). Children normally begin adrenarche at about age 8-9 before the onset of puberty. Clinical studies show that early, exaggerated adrenarche maybe an early sign of the polycystic ovary syndrome (PCOS), which affects 3-5 percent of women of reproductive age. PCOS women have increased secretion of C-19 androgens 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 androgen produced in both tissues. P450c17 catalyzes both 17alpha-hydroxylase and 17,20 lyase activities. Each activity requires the donation of a pair of electrons from p450 oxidoreductase (OR). The mechanisms of the tissue-specific expression of P450c17 in the adrenal and gonad are unknown. When expressed in the zona fasciculata, P450c17 catalyzes 17alpha- 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 precursor of androgens and estrogens. At least two factors regulate the 17,20 lyase activity of P450c17 at a post-translational level: the presence of cytochrome b5, which allosterically fosters the interaction of P450cl7 with OR, and serine phosphorylation of P450c17, which increases 17,20 lyase activity by unknown mechanisms. We propose to elucidate the key transcriptional and post-translational mechanisms of regulation of P450c17 by pursuing four specific aims. Aim 1: Identify the factors required for tissue-specific basal transcription of the human p450c17 gene. Aims 2: Identify the kinase(s) responsible for P450c17 phosphorylation. Aim 3: Determine whether the degree of phosphorylation of P450c17 is regulated by dephosphorylation (phosphatases). Aim 4: Determine how P450c17 phosphorylation influences 17,20 lyase activity. Fulfillment of these four aims will greatly 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.

肾上腺初现是青春期前后的事件，此时人类肾上腺开始产生大量 19 碳类固醇，尤其是脱氢表雄酮 (DHEA)。 儿童通常在青春期开始前的 8 至 9 岁左右开始肾上腺初现。临床研究表明，早期、过度的肾上腺功能初现可能是多囊卵巢综合征 (PCOS) 的早期征兆，该综合征影响 3-5% 的育龄妇女。 PCOS 女性的肾上腺和卵巢 C-19 雄激素的分泌增加。 细胞色素 p450c17 的 17,20 裂解酶活性将 17OH 孕烯醇酮转化为 DHEA，这决定了两种组织中产生的雄激素的量。 P450c17 催化 17α-羟化酶和 17,20 裂解酶活性。 每项活动都需要 p450 氧化还原酶 (OR) 捐赠一对电子。 P450c17 在肾上腺和性腺中组织特异性表达的机制尚不清楚。 当在束状带中表达时，P450c17 催化 17α-羟化酶，但很少催化 17,20 裂解酶活性以产生皮质醇。 当它在肾上腺网状带和性腺中表达时，它具有高17,20裂解酶活性，并催化DHEA（雄激素和雌激素的前体）的形成。至少有两个因素在翻译后水平调节 P450c17 的 17,20 裂解酶活性：细胞色素 b5 的存在（其以变构方式促进 P450c17 与 OR 的相互作用）和 P450c17 的丝氨酸磷酸化（其增加 17,20 裂解酶活性）未知的机制。 我们建议通过追求四个具体目标来阐明 P450c17 调控的关键转录和翻译后机制。 目标 1：确定人类 p450c17 基因组织特异性基础转录所需的因子。 目标 2：鉴定负责 P450c17 磷酸化的激酶。 目标 3：确定 P450c17 的磷酸化程度是否受到去磷酸化（磷酸酶）的调节。 目标 4：确定 P450c17 磷酸化如何影响 17,20 裂解酶活性。这四个目标的实现将极大地扩展我们对健康和疾病中雄激素产生调节机制的理解，并为患有多囊卵巢综合症的女性的肾上腺和性腺过量产生雄激素的机制提供新的见解。