Mouse Heart SS31 Targeted Proteomics

The S-glutathionylation and phosphorylation proteomes of mouse hearts were analyzed using shotgun proteomics methods in order to assess the effects of aging and the ability of mitochondrion-targeted drug SS-31 to reverse age-related changes. There was a nearly universal increase in S-gluthationylation of cysteine residues on proteins taken from Old (24 months old at the start of the study) mouse hearts compared to Young (5-6 months old). This shift in proteome oxidation state was almost completely reversed by 8-weeks of SS-31 treatment. Many of the significant changes that occurred were in mitochondrial pathways. Changes in phosphorylation did not show a clear pattern, as there was a mix of enhancement and suppression of phosphorylation with age among different proteins. SS-31 showed some effect at restoring the phosphorylation state of proteins that had increased phosphorylation with age but it had no effect on those that had decreased phosphorylation with age. A subset of phosphorylation sites was also analyzed by parallel reaction monitoring, which revealed that Myot S231 had a change in the proportion of phosphorylated and unphosphorylated proteins and that cMyBP-C S307 had a proportional increase in phosphorylated and unphosphorylated protein with age, but that SS-31 treatment did not affect these changes.