Department of Geriatrics, Fourth Military Medical University, Xi'an, Shaan-xi 710032, China.
Free Radic Biol Med. 2011 Nov 1;51(9):1736-48. doi: 10.1016/j.freeradbiomed.2011.08.002. Epub 2011 Aug 10.
Mitochondrial aldehyde dehydrogenase-2 (ALDH2) alleviates ethanol toxicity although the precise mechanism is unclear. This study was designed to evaluate the effect of ALDH2 on ethanol-induced myocardial damage with a focus on autophagy. Wild-type FVB and transgenic mice overexpressing ALDH2 were challenged with ethanol (3g/kg/day, ip) for 3days and cardiac mechanical function was assessed using the echocardiographic and IonOptix systems. Western blot analysis was used to evaluate essential autophagy markers, Akt and AMPK, and the downstream signal mTOR. Ethanol challenge altered cardiac geometry and function as evidenced by enlarged ventricular end systolic and diastolic diameters, decreased cell shortening and intracellular Ca(2+) rise, prolonged relengthening and intracellular Ca(2+) decay, as well as reduced SERCA Ca(2+) uptake, which effects were mitigated by ALDH2. Ethanol challenge facilitated myocardial autophagy as evidenced by enhanced expression of Beclin, ATG7, and LC3B II, as well as mTOR dephosphorylation, which was alleviated by ALDH2. Ethanol challenge-induced cardiac defect and apoptosis were reversed by the ALDH2 agonist Alda-1, the autophagy inhibitor 3-MA, and the AMPK inhibitor compound C, whereas the autophagy inducer rapamycin and the AMPK activator AICAR mimicked or exacerbated ethanol-induced cell injury. Ethanol promoted or suppressed phosphorylation of AMPK and Akt, respectively, in FVB but not ALDH2 murine hearts. Moreover, AICAR nullified Alda-1-induced protection against ethanol-triggered autophagic and functional changes. Ethanol increased GFP-LC3 puncta in H9c2 cells, the effect of which was ablated by Alda-1 and 3-MA. Lysosomal inhibition using bafilomycin A1, E64D, and pepstatin A obliterated Alda-1- but not ethanol-induced responses in GFP-LC3 puncta. Our results suggest that ALDH2 protects against ethanol toxicity through altered Akt and AMPK signaling and regulation of autophagic flux.
线粒体乙醛脱氢酶 2（ALDH2）可减轻乙醇毒性，但其确切机制尚不清楚。本研究旨在评估 ALDH2 对乙醇诱导心肌损伤的影响，重点关注自噬。野生型 FVB 和过表达 ALDH2 的转基因小鼠接受乙醇（3g/kg/天，ip）挑战 3 天，并使用超声心动图和 IonOptix 系统评估心脏机械功能。Western blot 分析用于评估必需的自噬标志物、Akt 和 AMPK 以及下游信号 mTOR。乙醇挑战改变了心脏几何形状和功能，表现为心室收缩末期和舒张末期直径增大、细胞缩短和细胞内 Ca(2+)升高减少、再延长和细胞内 Ca(2+)衰减延长，以及 SERCA Ca(2+)摄取减少，这些效应均被 ALDH2 减轻。乙醇挑战促进了心肌自噬，表现为 Beclin、ATG7 和 LC3B II 的表达增强，以及 mTOR 去磷酸化，而 ALDH2 减轻了这种自噬。ALDH2 激动剂 Alda-1、自噬抑制剂 3-MA 和 AMPK 抑制剂化合物 C 逆转了乙醇诱导的心脏缺陷和凋亡，而自噬诱导剂 rapamycin 和 AMPK 激活剂 AICAR 模拟或加重了乙醇诱导的细胞损伤。乙醇分别在 FVB 而不是 ALDH2 小鼠心脏中促进或抑制了 AMPK 和 Akt 的磷酸化。此外，AICAR 消除了 Alda-1 诱导的对乙醇触发的自噬和功能变化的保护作用。乙醇增加了 H9c2 细胞中的 GFP-LC3 斑点，Alda-1 和 3-MA 消除了这种作用。溶酶体抑制使用巴弗洛霉素 A1、E64D 和胃蛋白酶抑制剂 A 消除了 Alda-1-但不是乙醇诱导的 GFP-LC3 斑点反应。我们的结果表明，ALDH2 通过改变 Akt 和 AMPK 信号转导和自噬通量的调节来保护免受乙醇毒性。
