Dehydroepiandrosterone Sulfate (DHEAS) Stimulates the First Step in the Biosynthesis of Steroid Hormones
Dehydroepiandrosterone Sulfate (DHEAS) Stimulates the First Step in the Biosynthesis of Steroid Hormones
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DOI：
10.1371/journal.pone.0089727
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发表时间：
2014-02-21
期刊：
影响因子：
3.7
通讯作者：
Bernhardt, Rita
中科院分区：
文献类型：
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作者：
Neunzig, Jens;Bernhardt, Rita
硫酸脱氢表雄酮 (DHEAS) 是人体中最丰富的循环类固醇，在 20 岁至 30 岁之间浓度最高，但随着年龄的增长而显着下降。许多有益的功能都归因于 DHEAS。然而，关于多年来 DHEAS 摄入量的长期研究非常缺乏，并且迄今为止还缺少对 DHEAS 作用的分子研究。在本研究中，在重建的体外系统中分析了 DHEAS 在类固醇激素生物合成第一步和限速步骤中的作用，该系统由纯化的 CYP11A1、肾上腺素还蛋白和肾上腺素还素还原酶组成。 DHEAS 将胆固醇的转化提高了 26%。对 DHEAS 作用机制的详细分析表明，胆固醇与 CYP11A1 的结合亲和力增加，并增强了与电子转移伙伴肾上腺素的相互作用。差异光谱显示，在不添加和添加DHEAS的情况下，CYP11A1和胆固醇的K-d值分别为40+/-2.7μM和24.8+/-0.5μM。为了确定 CYP11A1 和肾上腺氧还蛋白的 K-d 值，进行了表面等离振子共振测量，证明 K-d 值为 3.0 +/- 0.35 nM（含胆固醇），添加胆固醇和 DHEAS 时为 2.4 +/- 0.05 nM。动力学实验表明，在 DHEAS 存在下，CYP11A1 具有较低的 K-m 和较高的 k(cat) 值，导致催化效率提高 75%。这些发现表明，DHEAS 在分子水平上影响类固醇激素的生物合成，导致孕烯醇酮的形成增加。
Dehydroepiandrosterone sulfate (DHEAS) is the most abundant circulating steroid in human, with the highest concentrations between age 20 and 30, but displaying a significant decrease with age. Many beneficial functions are ascribed to DHEAS. Nevertheless, long-term studies are very scarce concerning the intake of DHEAS over several years, and molecular investigations on DHEAS action are missing so far. In this study, the role of DHEAS on the first and rate-limiting step of steroid hormone biosynthesis was analyzed in a reconstituted in vitro system, consisting of purified CYP11A1, adrenodoxin and adrenodoxin reductase. DHEAS enhances the conversion of cholesterol by 26%. Detailed analyses of the mechanism of DHEAS action revealed increased binding affinity of cholesterol to CYP11A1 and enforced interaction with the electron transfer partner, adrenodoxin. Difference spectroscopy showed K-d-values of 40 +/- 2.7 mu M and 24.8 +/- 0.5 mu M for CYP11A1 and cholesterol without and with addition of DHEAS, respectively. To determine the K-d-value for CYP11A1 and adrenodoxin, surface plasmon resonance measurements were performed, demonstrating a K-d-value of 3.0 +/- 0.35 nM (with cholesterol) and of 2.4 +/- 0.05 nM when cholesterol and DHEAS were added. Kinetic experiments showed a lower K-m and a higher k(cat) value for CYP11A1 in the presence of DHEAS leading to an increase of the catalytic efficiency by 75%. These findings indicate that DHEAS affects steroid hormone biosynthesis on a molecular level resulting in an increased formation of pregnenolone.