Liang Faquan, Kapoun Ann M, Lam Andrew, Damm Debby L, Quan Diana, O'Connell Maile, Protter Andrew A
Scios Inc., 6500 Paseo Padre Parkway, Fremont, California 94555, USA.
Endocrinology. 2007 Aug;148(8):3722-9. doi: 10.1210/en.2006-1599. Epub 2007 May 3.
In this study, we demonstrate that B-type natriuretic peptide (BNP) opposed angiotensin II (Ang II)-stimulated de novo cholesterol biosynthesis, cellular cholesterol uptake, cholesterol transfer to the inner mitochondrial membrane, and steroidogenesis, which are required for biosynthesis of steroid hormones such as aldosterone and cortisol in primary human adrenocortical cells. BNP dose-dependently stimulated intracellular cGMP production with an EC(50) of 11 nm, implying that human adrenocortical cells express the guanylyl cyclase A receptor. cDNA microarray and real-time RT-PCR analyses revealed that BNP inhibited Ang II-stimulated genes related to cholesterol biosynthesis (acetoacetyl coenzyme A thiolase, HMG coenzyme A synthase 1, HMG coenzyme A reductase, isopentenyl-diphosphate Delta-isomerase, lanosterol synthase, sterol-4C-methyl oxidase, and emopamil binding protein/sterol isomerase), cholesterol uptake from circulating lipoproteins (scavenger receptor class B type I and low-density lipoprotein receptor), cholesterol transfer to the inner mitochondrial membrane (steroidogenic acute regulatory protein), and steroidogenesis (ferredoxin 1,3beta-hydroxysteroid dehydrogenase, glutathione transferase A3, CYP19A1, CYP11B1, and CYP11B2). Consistent with the microarray and real-time PCR results, BNP also blocked Ang II-induced binding of (125)I-labeled low-density lipoprotein and (125)I-labeled high-density lipoprotein to human adrenocortical cells. Furthermore, BNP markedly inhibited Ang II-stimulated release of estradiol, aldosterone, and cortisol from cultured primary human adrenocortical cells. These findings demonstrate that BNP opposes Ang II-induced steroidogenesis via multiple steps from cholesterol supply and transfer to the final formation of steroid hormones. This study provides new insights into the cellular mechanisms by which BNP modulates Ang II-induced steroidogenesis in the adrenal gland.
在本研究中，我们证明B型利钠肽（BNP）可对抗血管紧张素II（Ang II）刺激的从头胆固醇生物合成、细胞胆固醇摄取、胆固醇向内线粒体膜的转运以及类固醇生成，而这些过程是原代人肾上腺皮质细胞中醛固酮和皮质醇等类固醇激素生物合成所必需的。BNP以剂量依赖的方式刺激细胞内cGMP生成，其半数有效浓度（EC50）为11 nM，这意味着人肾上腺皮质细胞表达鸟苷酸环化酶A受体。cDNA微阵列和实时逆转录聚合酶链反应（RT-PCR）分析显示，BNP抑制与胆固醇生物合成相关的Ang II刺激基因（乙酰乙酰辅酶A硫解酶、HMG辅酶A合酶1、HMG辅酶A还原酶、异戊烯二磷酸δ-异构酶、羊毛甾醇合酶、甾醇4C-甲基氧化酶和埃莫帕米结合蛋白/甾醇异构酶）、从循环脂蛋白摄取胆固醇（B类I型清道夫受体和低密度脂蛋白受体）、胆固醇向内线粒体膜的转运（类固醇生成急性调节蛋白）以及类固醇生成（铁氧化还原蛋白1、3β-羟基类固醇脱氢酶、谷胱甘肽转移酶A3、CYP19A1、CYP11B1和CYP11B2）。与微阵列和实时PCR结果一致，BNP还阻断了Ang II诱导的125I标记的低密度脂蛋白和125I标记的高密度脂蛋白与人肾上腺皮质细胞的结合。此外，BNP显著抑制Ang II刺激的原代人肾上腺皮质细胞培养物中雌二醇、醛固酮和皮质醇的释放。这些发现表明，BNP通过从胆固醇供应和转运到类固醇激素最终形成的多个步骤对抗Ang II诱导的类固醇生成。本研究为BNP调节肾上腺中Ang II诱导的类固醇生成的细胞机制提供了新的见解。
