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个碳雄激素均通过顺序17-衍生出21碳类固醇 - 细胞色素P450C17（CYP17A1）的羟化酶和17,20-裂解酶活性。这 通过选择性刺激17,20-酶反应的复杂化学性质，最多可刺激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，显然涉及从B5转移的电子，我们的数据认为B5 变构激活CYP17A1的17,20-溶酶活性。我们已经确定了 B5的特定区域对于刺激17,20-裂解活性至关重要，并且已显示 这种刺激的大小依赖于底物。我们现在建议 阐明B5对17,20-裂解活性的作用机理，并比较 B5-CYP17A1与B5作用的机械和结构特征 其他P450介导的反应。 在AIM 1中，我们将确定关键保留的空间和电子要求 在CYP17A1和B5上刺激17,20-裂解活性。在AIM 2中，我们将 推断出使用B5增强的17,20-裂解反应的微观步骤 快速稳态的状态动力学实验。在AIM 3中，我们将确定是否相同 B5的表面对于刺激17,20-裂解活性很重要，也调节了活动 其他细胞色素P450以及是否适用于这些原理 其他反应。在AIM 4中，我们将设计B5的固体形式，该形式也刺激17,20-- 裂解酶活性，为CYP17A1-B5复合物的未来结构研究奠定了基础。 因此，我们将系统地定义B5对CYP17A1的作用机理， 通过 针对CYP17A1-B5相互作用。 涉及雄激素过量生产的疾病（例如多囊卵巢 综合征）和需要雄激素的疾病（例如前列腺癌）可能是 通过抑制雄激素合成治疗。当前可用的代理是 次优。通过定义酶17-羟化酶/17,20-酶如何使 雄激素，我们希望建立新的方法来治疗雄激素 人类疾病。我们还将确定这些原则是否适用于其他类似的 代谢药物的酶。抑制雄激素合成是当前对前列腺等人类疾病的治疗 癌症和多囊卵巢综合征。这种方法是次优的。通过定义如何 负责酶合成这些雄激素的酶，我们希望建立新的 治疗方法。我们的研究将适用于代谢药物的其他酶。