Role of calmodulin-dependent protein kinase II in the acute stimulation of aldosterone production.
Role of calmodulin-dependent protein kinase II in the acute stimulation of aldosterone production.
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钙调蛋白依赖性蛋白激酶 II 在急性刺激醛固酮产生中的作用。
DOI：
10.1016/0960-0760(96)00052-0
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Rainey,WE
中科院分区：
文献类型：
--
作者：
Pezzi,V;Clark,BJ;Ando,S;Stocco,DM;Rainey,WE
肾上腺皮质细胞中的急性醛固酮产生高度依赖于钙（Ca 2+）和钙调素（CaM）的激活。为了确定钙调素依赖性蛋白激酶II（CaM激酶II）在人肾上腺醛固酮产生中的作用，检测了KN 93（一种特异性CaM激酶II抑制剂）对人肾上腺皮质H295 R细胞的作用。KN 93呈浓度依赖性地抑制醛固酮刺激、血管紧张素II（Ang II）和钾离子（K+）的产生，IC_（50）分别为0.9 μ M和0.5 μ M。用钙通道激活剂Bay K 8644（Bay K）（1 μ M）处理也可刺激醛固酮产生。KN 93以浓度依赖性方式抑制这种产生，IC 50为1 - 3 μ M。KN 93（0.3 - 3 μ M）或钙调蛋白抑制剂calmidazolium（0.03 - 0.3 μ M）对22 R-羟基胆固醇（22 R-OHChol）刺激醛固酮生成无抑制作用。由于22R-OHChol是细胞色素P450胆固醇侧链裂解酶（P450SCC）的底物，不需要主动转运到线粒体，因此这些结果表明KN 93不直接抑制P450SCC或导致醛固酮合成的后续步骤。为了进一步研究KN93作用的位点，我们研究了其对类固醇生成急性调节（StAR）蛋白的激动剂诱导的作用，该蛋白最近被证明调节胆固醇从线粒体外膜到线粒体内膜的运动。Ang II或Bay K对H295 R细胞中StAR蛋白的诱导作用不受KN 93的影响，KN 93的浓度可阻断60 - 80%的类固醇合成。这些结果表明CaM激酶II在Ang II和K+刺激醛固酮产生中发挥直接作用，并支持CaM激酶II可能参与胆固醇动员至线粒体过程的假设。
Acute aldosterone production in adrenocortical cells is highly dependent on calcium (Ca2+) and calmodulin (CaM) activation. To determine the role of calmodulin-dependent protein kinase II (CaM kinase II) in human adrenal aldosterone production, the action of KN93 (a specific CaM kinase II inhibitor) on human adrenocortical H295R cells was examined. The stimulation of aldosterone, production by angiotensin II (Ang II) and potassium (K+) were inhibited by KN93 in a concentration-dependent manner with an IC50of ∼ 0.9 and ∼ 0.5 μM, respectively. Aldosterone production was also stimulated by treatment with the calcium channel activator Bay K 8644 (Bay K) (1 μM). This production was inhibited in a concentration-dependent manner by KN93 with an IC50of between 1 and 3 μM. No inhibition by KN93 (0.3–3 μM) or by the calmodulin inhibitor calmidazolium (0.03–0.3 μM) was observed for 22R-hydroxycholesterol (22R-OHChol) stimulation of aldosterone production. Because 22R-OHChol is a substrate for the cytochrome P450 cholesterol side-chain cleavage enzyme (P450scc) and does not require active transport to the mitochondria, these results indicate that KN93 does not directly inhibit P450scc or later steps leading to aldosterone synthesis. To investigate the site of KN93 action further we examined its effect on agonists induction of steroidogenic acute regulatory (StAR) protein, which was recently shown to regulate the movement of cholesterol from the outer to the inner mitochondrial membranes. Induction of StAR protein in H295R cells by Ang II, or Bay K was not affected by co-treatment with KN93 at concentration which blocked steroidogenesis by 60–80%. These results indicate a direct role of CaM kinase II in Ang II and K+simulation of aldosterone production and support the hypothesis that CaM kinase II may be involved in the process of cholesterol mobilization to the mitochondria.