Activation of androgen biosynthesis and drug metabolism by cytochrome b5

细胞色素 b5 激活雄激素生物合成和药物代谢

• 批准号: 8438169
• 负责人: RICHARD J. AUCHUS
• 金额: $ 24.81万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-30 至 2013-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8438169
• 关键词: Activation; androgen; biosynthesis; drug; metabolism

All 19-carbon androgens derive from 21-carbon steroids via sequential 17¿- hydroxylase and 17,20-lyase activities of cytochrome P450c17 (CYP17A1). The complex chemistry of the 17,20-lyase reaction is selectively stimulated up to 10-fold by cytochrome b5 (b5). In contrast to the interactions of b5 with some other cytochromes P450, which apparently involve electron transfer from b5, our data argue that b5 allosterically activates the 17,20-lyase activity of CYP17A1. We have identified a specific region of b5 that is critical for stimulation of 17,20-lyase activity and have shown that the magnitude of this stimulation is substrate-dependent. We now propose to elucidate the mechanism of action of b5 on 17,20-lyase activity and to compare the mechanistic and structural features of the b5-CYP17A1 interaction with b5 action on other P450-mediated reactions. In Aim 1, we will determine the steric and electronic requirements of key residues on CYP17A1 and b5 necessary to stimulate 17,20-lyase activity. In Aim 2, we will deduce the microscopic steps of the 17,20-lyase reaction that are enhanced by b5 using rapid and pre-steady state kinetics experiments. In Aim 3, we will determine if the same surface of b5 important for stimulating 17,20-lyase activity also modulates the activities of other cytochromes P450 and whether the same mechanistic principles apply to these other reactions. In Aim 4, we will engineer soluble forms of b5 that also stimulate 17,20- lyase activity, setting the stage for future structural studies of the CYP17A1-b5 complex. We thus will systematically define the mechanism of action of b5 on CYP17A1, potentially identifying novel approaches for suppressing androgen production, by targeting the CYP17A1-b5 interaction. Diseases that involve androgen overproduction (such as polycystic ovary syndrome) and diseases that require androgens (such as prostate cancer) can be treated by inhibition of androgen synthesis. Currently available agents are suboptimal. By defining how the enzyme 17-hydroxylase/17,20-lyase makes androgens, we hope to establish new approaches to treating androgen-dependent human diseases. We will also determine if these principles apply to other similar enzymes that metabolize drugs. Inhibition of androgen synthesis is the current treatment of human diseases like prostate cancer and polycystic ovary syndrome. This approach is suboptimal. By defining how the enzyme responsible synthesizes these androgens, we hope to establish new approaches to treatment. Our study will apply to other enzymes that metabolize drugs.

所有 19 碳雄激素均通过连续 17¿ 衍生自 21 碳类固醇- 细胞色素 P450c17 (CYP17A1) 的羟化酶和 17,20-裂解酶活性。 17,20-裂解酶反应的复杂化学反应被选择性地刺激高达 10 倍 细胞色素 b5 (b5) 与 b5 与其他一些细胞色素的相互作用相反。 P450，显然涉及 b5 的电子转移，我们的数据表明 b5 变构激活 CYP17A1 的 17,20-裂解酶活性。 b5 的特定区域对于刺激 17,20-裂解酶活性至关重要，并且已表明 我们现在建议这种刺激的强度取决于底物。 阐明 b5 对 17,20-裂合酶活性的作用机制并比较 b5-CYP17A1 与 b5 作用的相互作用的机制和结构特征 其他 P450 介导的反应。 在目标 1 中，我们将确定关键残基的空间和电子要求 在目标 2 中，我们将刺激 17,20-裂解酶活性所必需的 CYP17A1 和 b5。 使用 b5 推导出 17,20-裂解酶反应的微观步骤 在目标 3 中，我们将确定快速和预稳态动力学实验是否相同。 b5 表面对于刺激 17,20-裂解酶活性很重要，也调节该活性 其他细胞色素 P450 的作用以及相同的机械原理是否适用于这些 在目标 4 中，我们将设计可溶形式的 b5，它也能刺激 17,20-。 裂解酶活性，为 CYP17A1-b5 复合物的未来结构研究奠定基础。 因此，我们将有意定义 b5 对 CYP17A1 的作用机制， 潜在地确定抑制雄激素产生的新方法，通过 靶向 CYP17A1-b5 相互作用。 涉及雄激素过量产生的疾病（例如多囊卵巢 综合征）和需要雄激素的疾病（例如前列腺癌）可以 目前可用的药物是通过抑制雄激素合成来治疗的。 通过定义酶 17-羟化酶/17,20-裂解酶如何产生。 雄激素，我们希望建立治疗雄激素依赖性的新方法 我们还将确定这些原则是否适用于其他类似的疾病。 抑制雄激素合成是目前治疗前列腺等人类疾病的方法。 通过定义如何治疗癌症和多囊卵巢综合症。 负责合成这些雄激素的酶，我们希望建立新的 我们的研究将适用于代谢药物的其他酶。