Abstract 10909: Cyclosporine a Attenuates Acetylation of Mitochondrial Proteins: Implications for Cardioprotection Against Ischemia/Reperfusion Injury
Acetylation/deacetylation of proteins on lysine residues has emerged as an important posttranslational modification of many proteins. Recent data suggests that cardioprotection by ischemic preconditioning leads to a decrease in protein acetylation. We hypothesized that another cardioprotective agent, cyclosporine A (CsA) might also alter protein acetylation to confer cardioprotection. CsA has been reported to reduce ischemia/reperfusion (IR) injury through inhibition of the mitochondrial permeability pore (mPTP) opening. Administration of CsA in isolated mouse hearts for 5 min prior to 20 min of ischemia and 2 hr of reperfusion improved post-ischemic contractile dysfunction (59.0 ± 8.3% vs. 37.3 ± 3.5%) and reduced myocardial cell death (12.7 ± 4.5% vs. 33.2 ± 4.1%) (, (n=4). We next assessed acetylation levels of mitochondrial proteins by Western blot analyses using anti-acetyl lysine antibody. Mitochondria isolated from CsA-perfused hearts showed a 51 + 7.0 % reduction in acetylation level (n=3, p<0.05). To identify the changes in lysine-acetylated proteins and map acetylation sites following CsA treatment, we subjected tryptic digests of isolated mitochondria to immunoprecipitation studies using agarose beads-coupled to anti-acetyl lysine antibody followed by mass spectrometry. We identified 178 proteins that showed decreased acetylation following CsA treatment (n=3, p<0.05). These proteins with reduced acetylation regulate diverse protein classes and mitochondrial biological pathways including lysine degradation, oxidative phosphorylation, and fatty acid metabolism. Of interest, cyclophilin D, the phosphate carrier, and ADP/ATP translocases 1/2 showed a ∼40% reduction in acetylation, suggesting a role for acetylation in regulating potential components or modulators of the mPTP. In addition, mitochondrial manganese superoxide dismutase (MnSOD) was deacetylated by 34 % (p<0.05), which is consistent with the reported that Sirtuin3 deacetylates and activates MnSOD to scavenge reactive oxygen species. Taken together, these results suggest that acute treatment of CsA leads to changes in acetylation profiles of the mitochondrial proteome to confer cardioprotection.
- © 2011 by American Heart Association, Inc.