In
obesity-linked
insulin resistance, oxidative stress in adipocytes leads to lipid peroxidation and subsequent carbonylation of
proteins by diffusible
lipid electrophiles. Reduction in oxidative stress attenuates protein carbonylation and
insulin resistance, suggesting that
lipid modification of
proteins may play a role in
metabolic disease, but the mechanisms remain incompletely understood. Herein, we show that in vivo, diet-induced
obesity in mice surprisingly results in preferential carbonylation of
nuclear proteins by 4-hydroxy-trans-2,3-nonenal (4-HNE) or 4-hydroxy-trans-2,3-hexenal (4-HHE). Proteomic and structural analyses revealed that residues in or around the sites of
zinc coordination of zinc finger
proteins, such as those containing the C2H2 or MATRIN, RING, C3H1, or N4-type
DNA-binding domains, are particularly susceptible to carbonylation by
lipid aldehydes. These observations strongly suggest that carbonylation functionally disrupts
protein secondary structure supported by
metal coordination. Analysis of one such target, the
nuclear protein estrogen-related receptor γ (ERR-γ), showed that ERR-γ is modified by 4-HHE in the obese state. In vitro carbonylation decreased the
DNA-binding capacity of ERR-γ and correlated with the
obesity-linked down-regulation of many key genes promoting mitochondrial bioenergetics. Taken together, these findings reveal a novel mechanistic connection between oxidative stress and metabolic dysfunction arising from carbonylation of nuclear zinc finger
proteins, such as the transcriptional regulator ERR-γ.