Department of Pharmacology, Aging-Associated Vascular Disease Research Center, College of Medicine, Yeungnam University, Daegu 705-717, Republic of Korea.
Biochem Biophys Res Commun. 2012 Sep 7;425(4):866-72. doi: 10.1016/j.bbrc.2012.07.165. Epub 2012 Aug 7.
Atherosclerosis is a chronic inflammation of the coronary arteries. Vascular smooth muscle cells (VSMCs) stimulated by cytokines and chemokines accelerate the inflammatory response and migrate to the injured endothelium during the progression of atherosclerosis. Activation of AMP activated protein kinase (AMPK), a key sensor maintaining metabolic homeostasis, suppresses the inflammatory response. However, how AMPK regulates the inflammatory response is poorly understood. To identify the mechanism of this response, we focused on phosphatase and tensin homolog (PTEN), which is a negative regulator of inflammation. We investigated that activation of AMPK-induced PTEN expression and suppression of the inflammatory response through the AMPK-PTEN pathway in VSMCs. We treated with the well-known AMPK activator metformin to induce PTEN expression. PTEN was induced by metformin (2mM) and inhibited by compound C (10 μM) and AMPK siRNA. Tumor necrosis factor-alpha (TNF-α) was used to induce inflammation. The inflammatory response was confirmed by cyclooxygenase (COX)-2, inducible nitric oxide synthase (iNOS) expression, and activation of nuclear factor (NF)-κB. Metformin suppressed COX-2 and iNOS mRNA and protein expression dose dependently. Treatment with compound C and bpv (pic) in the presence of metformin, iNOS and COX-2 protein expression increased. NF-κB activation decreased in response to metformin and was restored by inhibiting AMPK and PTEN. Inhibiting AMPK and PTEN restored ROS levels stimulated with TNF-α. Taken together, PTEN could be a possible downstream regulator of AMPK, and the AMPK-PTEN pathway might be important in the regulation of the inflammatory response in VSMCs.
动脉粥样硬化是冠状动脉的一种慢性炎症。细胞因子和趋化因子刺激的血管平滑肌细胞（VSMCs）在动脉粥样硬化进展过程中加速炎症反应并迁移到受损的内皮细胞。激活 AMP 激活蛋白激酶（AMPK），一种维持代谢稳态的关键传感器，可抑制炎症反应。然而，AMPK 如何调节炎症反应知之甚少。为了确定这种反应的机制，我们专注于磷酸酶和张力蛋白同系物（PTEN），它是炎症的负调节剂。我们研究了 AMPK 诱导的 PTEN 表达及其通过 AMPK-PTEN 通路在 VSMCs 中抑制炎症反应的机制。我们用著名的 AMPK 激活剂二甲双胍处理以诱导 PTEN 表达。二甲双胍（2mM）诱导 PTEN 表达，并用化合物 C（10μM）和 AMPK siRNA 抑制。肿瘤坏死因子-α（TNF-α）用于诱导炎症。环加氧酶（COX）-2、诱导型一氧化氮合酶（iNOS）表达和核因子（NF）-κB 的激活证实了炎症反应。二甲双胍呈剂量依赖性抑制 COX-2 和 iNOS mRNA 和蛋白表达。在用二甲双胍存在的情况下用化合物 C 和 bpv（pic）处理，iNOS 和 COX-2 蛋白表达增加。NF-κB 激活随二甲双胍而降低，并通过抑制 AMPK 和 PTEN 得以恢复。抑制 AMPK 和 PTEN 恢复了 TNF-α刺激的 ROS 水平。总之，PTEN 可能是 AMPK 的一个潜在下游调节剂，AMPK-PTEN 通路可能在 VSMCs 中调节炎症反应中起重要作用。
