Center for Cardiovascular Research and Alternative Medicine, University of Wyoming College of Health Sciences, Laramie, WY 82071, USA.
Cardiovasc Res. 2012 Jun 1;94(3):480-91. doi: 10.1093/cvr/cvs127. Epub 2012 Mar 26.
Binge drinking often triggers compromised myocardial contractile function while activating AMP-activated protein kinase (AMPK). Given the role of AMPK in the initiation of autophagy through the mammalian target of rapamycin complex 1 (mTORC1) and Unc51-like kinase (ULK1), this study was designed to examine the impact of AMPK deficiency on cardiac function and the mechanism involved with a focus on autophagy following an acute ethanol challenge.
Wild-type (WT) and transgenic mice overexpressing a kinase-dead (KD) α2 isoform (K45R mutation) of AMPK were challenged with ethanol. Glucose tolerance, echocardiography, Langendorff heart and cardiomyocyte contractile function, autophagy, and autophagic signalling including AMPK, acetyl-CoA carboxylase (ACC), mTOR, the mTORC1-associated protein Raptor, and ULK1 were examined. Ethanol exposure triggered glucose intolerance and compromised cardiac contraction accompanied by increased phosphorylation of AMPK and ACC as well as autophagosome accumulation (increased LC3II and p62), the effects of which were attenuated or mitigated by AMPK deficiency or inhibition. Ethanol dampened and stimulated, respectively, the phosphorylation of mTOR and Raptor, the effects of which were abolished by AMPK deficiency. ULK1 phosphorylation at Ser(757) and Ser(777) was down-regulated and up-regulated, respectively, by ethanol, the effect of which was nullified by AMPK deficiency or inhibition. Moreover, the ethanol challenge enhanced LC3 puncta in H9c2 cells and promoted cardiac contractile dysfunction, and these effects were ablated by the inhibition of autophagy or AMPK. Lysosomal inhibition failed to accentuate ethanol-induced increases in LC3II and p62.
In summary, these data suggest that ethanol exposure may trigger myocardial dysfunction through a mechanism associated with AMPK-mTORC1-ULK1-mediated autophagy.
binge drinking（狂饮）常常会损害心肌的收缩功能，同时激活 AMP-activated protein kinase（AMPK）。鉴于 AMPK 在通过 mammalian target of rapamycin complex 1（mTORC1）和 Unc51-like kinase（ULK1）引发自噬中的作用，本研究旨在探讨 AMPK 缺乏对心脏功能的影响以及涉及自噬的机制，重点关注急性乙醇刺激后的自噬。
野生型（WT）和过表达激酶失活（KD）α2 同工型（K45R 突变）的 AMPK 的转基因小鼠接受乙醇挑战。检查葡萄糖耐量、超声心动图、Langendorff 心脏和心肌收缩功能、自噬以及自噬信号，包括 AMPK、acetyl-CoA carboxylase（ACC）、mTOR、mTORC1 相关蛋白 Raptor 和 ULK1。乙醇暴露引发葡萄糖不耐受和心脏收缩功能受损，同时伴有 AMPK 和 ACC 的磷酸化增加以及自噬体积累（LC3II 和 p62 增加），这些效应被 AMPK 缺乏或抑制所减弱或缓解。乙醇分别抑制和刺激 mTOR 和 Raptor 的磷酸化，这些效应被 AMPK 缺乏所消除。乙醇下调 ULK1 在 Ser(757)和 Ser(777)的磷酸化，上调磷酸化，这些效应被 AMPK 缺乏或抑制所消除。此外，乙醇挑战增加了 H9c2 细胞中的 LC3 斑点，并促进了心脏收缩功能障碍，这些效应被自噬或 AMPK 的抑制所消除。溶酶体抑制未能加重乙醇诱导的 LC3II 和 p62 的增加。
总之，这些数据表明，乙醇暴露可能通过与 AMPK-mTORC1-ULK1 介导的自噬相关的机制引发心肌功能障碍。
