Shaanxi Key Laboratory of Ischemic Cardiovascular Disease, Institute of Basic and Translational Medicine, Xi'an Medical University, Xi'an, Shaanxi, 710021, China.
The First Affiliated Hospital of Xi'an Medical University, Xi'an Medical University, Xi'an, Shaanxi, 710077, China.
Microvasc Res. 2018 Sep;119:13-21. doi: 10.1016/j.mvr.2018.03.010. Epub 2018 Mar 27.
The change of autophagy is implicated in cardiovascular diseases (CVDs). Homocysteine (Hcy) up-regulates endothelin type B (ET) receptors in vascular smooth muscle cells (VSMCs). However, it is unclear whether autophagy is involved in Hcy-induced-up-regulation of ET receptors in VSMCs. The present study was designed to examine the hypothesis that Hcy up-regulates ET receptors by inhibiting autophagy in VSMCs. Hcy treated the rat superior mesenteric artery (SMA) without endothelium in the presence and absence of AICAR, rapamycin or MHY1485 for 24 h. The contractile responses to sarafotoxin 6c (S6c) (an ET receptor agonist) were studied using a sensitive myograph. Levels of protein expression were determined using Western blot analysis. Punctate staining of LC3B was exanimated by immunofluorescence using confocal microscopy. The results showed that Hcy inhibited AMPK, and activated mTOR, followed by impairing autophagy, and increased the levels of ET receptor protein expression and the ET receptor-mediated contractile responses to S6c in SMA without endothelium. However, these effects were reversed by AICAR or rapamycin. Additionally, MHY1485 up-regulated the AICAR-inhibited ET receptor-mediated contractile response and the levels of ET receptor protein expression in presence of Hcy. In conclusion, this suggested that Hcy up-regulated ET receptors by inhibiting autophagy in VSMCs via AMPK/mTOR signaling pathway.
自噬的变化与心血管疾病 (CVDs) 有关。同型半胱氨酸 (Hcy) 上调血管平滑肌细胞 (VSMCs) 中的内皮素 B 型 (ET) 受体。然而，尚不清楚自噬是否参与 Hcy 诱导的 VSMCs 中 ET 受体的上调。本研究旨在检验以下假设：Hcy 通过抑制 VSMCs 中的自噬来上调 ET 受体。在存在和不存在 AICAR、雷帕霉素或 MHY1485 的情况下，用 Hcy 处理无内皮的大鼠肠系膜上动脉 (SMA) 24 小时。使用灵敏的肌动描记器研究沙罗毒素 6c (S6c)（一种 ET 受体激动剂）引起的收缩反应。使用 Western blot 分析测定蛋白表达水平。通过共聚焦显微镜用免疫荧光法检查 LC3B 的点状染色。结果表明，Hcy 抑制 AMPK，激活 mTOR，随后损害自噬，并增加 ET 受体蛋白表达水平和无内皮 SMA 中 S6c 介导的 ET 受体收缩反应。然而，这些作用被 AICAR 或雷帕霉素逆转。此外，MHY1485 上调了存在 Hcy 时 AICAR 抑制的 ET 受体介导的收缩反应和 ET 受体蛋白表达水平。总之，这表明 Hcy 通过 AMPK/mTOR 信号通路抑制 VSMCs 中的自噬来上调 ET 受体。
