Expression of CYP2E1 increases oxidative stress and induces apoptosis of cardiomyocytes in transgenic mice

Cytochrome P450 2E1 (CYP2E1) is an effective generator of reactive oxygen species. Marked expression of CYP2E1 occurs in the heart and it is known to be regulated in the course of progression of myocardial ischemia and cardiomyopathy. We provide evidence that the expression of CYP2E1 is strongly up-regulated in cTnTR141W transgenic mice with dilated cardiomyopathy. Heart tissue-specific CYP2E1 transgenic mice were produced to study the effects of CYP2E1 overexpression on the heart. Increased mortality, chamber dilation and contractile dysfunction, as well as myocyte disarray, interstitial fibrosis, ultrastructural degeneration with myofibrillar disorganization and mitochondria damage, were observed in CYP2E1 transgenic mice and cTnTR141W transgenic mice. In addition, levels of H2O2 and malondialdehyde were increased and levels of glutathione and total antioxidant capability were strongly reduced in CYP2E1 transgenic mice and cTnTR141W transgenic mice. Myocyte apoptosis was significantly increased by 19-fold in CYP2E1 transgenic mice and by 11-fold in cTnTR141W transgenic mice, respectively, compared to wild-type mice. Mitochondrial-dependent apoptotic signal transduction events, such as cytochrome c release from mitochondria into the cytosol and the expression of cleaved (active) caspases 3 and 9, were significantly increased in CYP2E1 transgenic mice and cTnTR141W transgenic mice. These results demonstrate that CYP2E1 over-expression produces apoptosis and that the up-regulation of CYP2E1 in cTnTR141W transgenic mice also correlates with apoptosis in this model.