Cyclophilin D Modulates Mitochondrial Acetylome

Abstract

Rationale Mice lacking cyclophilin D (CypD−/−), a mitochondrial chaperone protein, have altered cardiac metabolism. As acetylation has been shown to regulate metabolism, we tested whether changes in protein acetylation might play a role in these metabolic changes in CypD−/− hearts. Objective To test the hypothesis that loss of CypD alters the cardiac mitochondrial acetylome. Methods and Results To identify changes in lysine-acetylated proteins and map acetylation sites following ablation of CypD, we subjected tryptic digests of isolated cardiac mitochondria from WT and CypD−/− mice to immunoprecipitation using agarose beads coupled to anti-acetyl lysine antibodies followed by mass spectrometry. We used label-free analysis for the relative quantification of the 875 common peptides that were acetylated in WT and CypD−/− samples and found 11 peptides (10 proteins) decreased and 96 peptides (48 proteins) increased in the CypD−/− samples. We found increased acetylation of proteins in fatty acid oxidation and branched-chain amino acid metabolism. To evaluate whether this increase in acetylation might play a role in the inhibition of fatty acid oxidation that was previously reported in CypD−/− hearts, we measured the activity of L-3-hydroxyacyl-CoA dehydrogenase (LCHAD), which was acetylated in the CypD−/− hearts. Consistent with the hypothesis, LCHAD activity was inhibited by approximately 50% compared to the WT mitochondria. Conclusions These results implicate a role for CypD in modulating protein acetylation. Taken together, these results suggest that ablation of CypD leads to changes in the mitochondrial acetylome, which may contribute to altered mitochondrial metabolism in CypD−/− mice.

Cyclophilin D and myocardial ischemia–reperfusion injury: A fresh perspective

“…These tissue-specific IMM mPTP/apoptosis [87] differences in mitochondrial metabolism may be a consequence of variable expression of CypD and/or that of its interacting partners which remain an open question for future studies. The recent discovery of acetylated mitochondrial proteome in CypD KO heart has triggered an interesting discussion about the role of lysine modification in heart pathophysiology [111]. The finding that CypD KO hearts have extensive hyperacetylation of many mitochondrial proteins, some of them are key enzymes involved in metabolic processes, goes in line with the previous studies reporting that CypD KO hearts have defects in various metabolic pathways [48,112].…”

“…As discussed previously, the increased lysine acetylation of the mitochondrial proteins in CypD KO hearts may be a consequence of reduced mitochondrial NAD + /NADH ratio which may cause a deficiency in SIRT3 activity. However, as described in this work, the protein acetylation profile from SIRT3 KO and CypD KO hearts has very little overlap suggesting the involvement of other, as yet unknown, mitochondrial acetylation modifying enzymes [111,113].…”

“…All of the above mentioned data tend to disclose important contribution of CypD acetylation/deacetylation in mPTP modulation. Although SIRT3 KO mice have been reported to possess increased cardiac IR injury [121], a lack of mPTP sensitization in SIRT3 KO mitochondria questions the very role of CypD acetylation in mPTP formation [111]. Therefore, further studies are required to establish the participation of acetylated CypD in mPTP induction.…”

Mitochondria and aging: A role for the mitochondrial transition pore?

“…A possible link between both studies was provided by Nguyen et al. (2013) who demonstrated using CypD −/− mice that CypD could modulate mitochondrial protein acetylation and thus mitochondrial metabolic changes in addition to its mPTP regulating properties.…”

Mitochondrion as a Target for Heart Failure Therapy – Role of Protein Lysine Acetylation –

“…14,92,104,107 Increased LysAc in the heart of cyclophilin D (CypD)-null mice is associated with propensity to HF during pressure overload, metabolic inflexibility and mitochondrial swelling. 14, 107 In a genetic model of mitochondrial complex I deficiency due to cardiac specific deletion of Ndufs4, decreased complex I function results in lower NAD + /NADH ratio, increased mitochondrial LysAc, and higher sensitivity of mPTP opening. 92 These mice also developed accelerated HF when subjected to chronic stresses.…”