Aldosterone suppresses insulin signaling via the downregulation of insulin receptor substrate-1 in vascular smooth muscle cells
Aldosterone suppresses insulin signaling via the downregulation of insulin receptor substrate-1 in vascular smooth muscle cells
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DOI：
10.1161/hypertensionaha.107.093955
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发表时间：
2007-10-01
期刊：
影响因子：
8.3
通讯作者：
Kohno, Masakazu
中科院分区：
文献类型：
--
作者：
Hitomi, Hirofumi;Kiyomoto, Hideyasu;Kohno, Masakazu
临床报告表明，原发性醛固酮增多症患者通常存在糖耐量受损；然而醛固酮与胰岛素信号通路之间的关系尚未阐明。在本研究中，我们检测了醛固酮治疗对大鼠血管平滑肌细胞中胰岛素受体底物-1 表达和胰岛素信号通路（包括 Akt 磷酸化和葡萄糖摄取）的影响。分别使用抗胰岛素受体底物-1 和磷酸化 Akt 抗体通过蛋白质印迹分析测定胰岛素受体底物-1 蛋白表达和 Akt 磷酸化。使用 3 H 标记的 2-脱氧-D-葡萄糖摄取评估葡萄糖代谢。醛固酮 (1-100 nmol/L) 剂量依赖性地降低胰岛素受体底物 1 蛋白表达，并在 18 小时达到峰值 (n = 4)。选择性盐皮质激素受体拮抗剂依普利酮（10 μmol/L；n = 4）治疗可显着减弱醛固酮诱导的胰岛素受体底物-1 降解。此外，Src 抑制剂 PP1（20 μmol/L；n = 4）可阻止降解。使用抗氧化剂、N-乙酰半胱氨酸 (10 mmol/L) 或依布硒啉 (40 μmol/L) 治疗也可减弱醛固酮诱导的胰岛素受体底物 1 降解 (n = 4)。此外，蛋白酶体抑制剂MG132（1μmol/L）可防止胰岛素受体底物1降解（n = 4）。醛固酮治疗消除了胰岛素诱导的 Akt 磷酸化（100 nmol/L；5 分钟；n = 4）。此外，醛固酮预处理使胰岛素刺激（100 nmol/L；60 分钟；n = 4）的葡萄糖摄取减少了 50%，而依普利酮（10 μmol/L；n = 4）则逆转了这一现象。这些数据表明，醛固酮通过血管平滑肌细胞中蛋白酶体依赖性降解的 Src 和活性氧刺激来降低胰岛素受体底物 1 的表达；因此，醛固酮可能通过氧化应激参与血管胰岛素抵抗的发病机制。
Clinical reports indicate that patients with primary aldosteronism commonly have impaired glucose tolerance; however, the relationship between aldosterone and insulin signaling pathway has not been clarified. In this study, we examined the effects of aldosterone treatment on insulin receptor substrate-1 expression and insulin signaling pathway including Akt phosphorylation and glucose uptake in rat vascular smooth muscle cells. Insulin receptor substrate-1 protein expression and Akt phosphorylation were determined by Western blot analysis with anti-insulin receptor substrate-1 and phosphorylated-Akt antibodies, respectively. Glucose metabolism was evaluated using 3H-labeled 2-deoxy-D-glucose uptake. Aldosterone (1-100 nmol/L) dose-dependently decreased insulin receptor substrate-1 protein expression with a peak at 18 hours (n = 4). Aldosterone-induced degradation of insulin receptor substrate-1 was markedly attenuated by treatment with the selective mineralocorticoid receptor antagonist eplerenone (10 mu mol/L; n = 4). Furthermore, degradation was blocked by the Src inhibitor PP1 (20 mu mol/L; n = 4). Treatment with antioxidants, N-acetylcysteine (10 mmol/L), or ebselen (40 mu mol/L) also attenuated aldosterone-induced insulin receptor substrate-1 degradation (n = 4). In addition, proteasome inhibitor MG132 (1 mu mol/L) prevented insulin receptor substrate-1 degradation (n = 4). Aldosterone treatment abolished insulin-induced Akt phosphorylation (100 nmol/L; 5 minutes; n = 4). Furthermore, aldosterone pretreatment decreased insulin-stimulated (100 nmol/L; 60 minutes; n = 4) glucose uptake by 50%, which was reversed by eplerenone (10 mu mol/L; n = 4). These data indicate that aldosterone decreases insulin receptor substrate-1 expression via Src and reactive oxygen species stimulation by proteasome-dependent degradation in vascular smooth muscle cells; thus, aldosterone may be involved in the pathogenesis of vascular insulin resistance via oxidative stress.