Acetaldehyde, the major metabolite of
ethanol, which is far more toxic and reactive than
ethanol, may be responsible for alcohol-induced cardiac damage. This study was designed to examine the impact of facilitated
acetaldehyde metabolism using transfection of human
aldehyde dehydrogenase-2 (ALDH2) transgene on
acetaldehyde- and
ethanol-induced cell injury. Fetal human cardiac myocytes were transfected with ALDH2, the efficacy of which was verified by flow cytometry, Western blot and ALDH2 activity assays. Generation of
reactive oxygen species (ROS) was detected using 5-(6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate (CM-H2DCFDA). Apoptosis was evaluated by 4',6'-diamidino-2'-phenylindoladihydrochloride (
DAPI) fluorescence microscopy, quantitative DNA fragmentation ELISA and
caspase 3 activity.
Acetaldehyde and
ethanol elicited overt ROS generation and apoptosis in human cardiac myocytes following 24-48 h of incubation. Immunostaining revealed activation of the MAP kinase cascades ERK1/2, SAPK/JNK and
p38 MAP kinase in
acetaldehyde-treated myocytes. Interestingly, ALDH2 transgene significantly attenuated
acetaldehyde-induced ROS generation, apoptosis and phosphorylation of ERK1/2 and SAPK/JNK. Time-dependent response (0-12 h) revealed ROS accumulation and activation of MAP
kinases prior to
acetaldehyde-induced apoptosis. In addition,
acetaldehyde-induced ROS generation and apoptosis were antagonized by non-enzymatic
antioxidants. Our results suggested that ALDH2 transgene overexpression may effectively alleviate
acetaldehyde-elicited cell injury through an ERK1/2 and SPAK/JNK-dependent mechanism. Our data are consistent with the notion of
acetaldehyde as a contributor to
alcoholic cardiomyopathy and implicate the therapeutic potential of ALDH2
enzyme in alcoholic complications.