the generation of both ROS and RNS levels [8–10,16], leading to increased production of peroxynitrite, which can modify the function of various proteins [31]. Consistent with this view, we found that the lipid peroxidation levels and oxidized and nitrated proteins were highest in WT-HFD mice. Oxidative/nitrosative events are well-documented to cause DNA damage and oxidative post-translational modifications of Cys-residues of cellular proteins [15,31,32], which negatively affect essential functions essential proteins prior to the observation of full-blown liver diseases [15,32]. Earlier studies revealed that the amounts of nitrated proteins, marker of NO-dependent nitrosative stress, were increased in the livers of obese ob/ob mice [33], explaining a potential role of 3-NT in causing the low mitochondrial respiratory chain activity in patients suffering from NASH. Our data also showed that nitrated protein levels are remarkably increased in the WT-HFD group compared to the other three groups (Fig. 2), suggesting that elevated levels of oxidative/nitrosative stress caused by, but may not be limited to CYP2E1, have increased protein oxidation and nitration, both of which might have also contributed to the progression to NASH development following steatosis.
