Seremwe Mutsa, Schnellmann Rick G, Bollag Wendy B
Charlie Norwood Veterans Administration Medical Center (W.B.B.), Augusta, Georgia 30904; Department of Physiology (M.S., W.B.B.) and Section of Dermatology (W.B.B.), Department of Medicine, Georgia Regents University, Augusta, Georgia 30912; and Department of Drug Discovery and Biomedical Sciences (R.G.S.), Medical University of South Carolina, and Ralph H. Johnson VA Medical Center (R.G.S.), Charleston, South Carolina 29425.
Endocrinology. 2015 Jun;156(6):2138-49. doi: 10.1210/en.2014-1866. Epub 2015 Apr 2.
Aldosterone is a steroid hormone important in the regulation of blood pressure. Aberrant production of aldosterone results in the development and progression of diseases including hypertension and congestive heart failure; therefore, a complete understanding of aldosterone production is important for developing more effective treatments. Angiotensin II (AngII) regulates steroidogenesis, in part through its ability to increase intracellular calcium levels. Calcium can activate calpains, proteases classified as typical or atypical based on the presence or absence of penta-EF-hands, which are involved in various cellular responses. We hypothesized that calpain, in particular calpain-10, is activated by AngII in adrenal glomerulosa cells and underlies aldosterone production. Our studies showed that pan-calpain inhibitors reduced AngII-induced aldosterone production in 2 adrenal glomerulosa cell models, primary bovine zona glomerulosa and human adrenocortical carcinoma (HAC15) cells, as well as CYP11B2 expression in the HAC15 cells. Although AngII induced calpain activation in these cells, typical calpain inhibitors had no effect on AngII-elicited aldosterone production, suggesting a lack of involvement of classical calpains in this process. However, an inhibitor of the atypical calpain, calpain-10, decreased AngII-induced aldosterone production. Consistent with this result, small interfering RNA (siRNA)-mediated knockdown of calpain-10 inhibited aldosterone production and CYP11B2 expression, whereas adenovirus-mediated overexpression of calpain-10 resulted in increased AngII-induced aldosterone production. Our results indicate that AngII-induced activation of calpain-10 in glomerulosa cells underlies aldosterone production and identify calpain-10 or its downstream pathways as potential targets for the development of drug therapies for the treatment of hypertension.
醛固酮是一种对血压调节很重要的类固醇激素。醛固酮的异常产生会导致包括高血压和充血性心力衰竭在内的疾病的发生和发展；因此，全面了解醛固酮的产生对于开发更有效的治疗方法很重要。血管紧张素II（AngII）部分通过其增加细胞内钙水平的能力来调节类固醇生成。钙可以激活钙蛋白酶，根据是否存在五聚体EF手结构将其分类为典型或非典型蛋白酶，这些蛋白酶参与各种细胞反应。我们假设钙蛋白酶，特别是钙蛋白酶-10，在肾上腺球状带细胞中被AngII激活，并参与醛固酮的产生。我们的研究表明，泛钙蛋白酶抑制剂在两种肾上腺球状带细胞模型，即原代牛球状带细胞和人肾上腺皮质癌细胞（HAC15）中，可降低AngII诱导的醛固酮产生，以及HAC15细胞中CYP11B2的表达。尽管AngII在这些细胞中诱导了钙蛋白酶的激活，但典型的钙蛋白酶抑制剂对AngII诱导的醛固酮产生没有影响，这表明经典钙蛋白酶不参与此过程。然而，非典型钙蛋白酶钙蛋白酶-10的抑制剂可降低AngII诱导的醛固酮产生。与这一结果一致，小干扰RNA（siRNA）介导的钙蛋白酶-10敲低抑制了醛固酮产生和CYP11B2表达，而腺病毒介导的钙蛋白酶-10过表达导致AngII诱导的醛固酮产生增加。我们的结果表明，AngII诱导的球状带细胞中钙蛋白酶-10的激活是醛固酮产生的基础，并将钙蛋白酶-10或其下游途径确定为开发高血压药物治疗的潜在靶点。
