Abstract P1061: Crosstalk Between Acetylation And Methylglyoxal Modifications On Myofilament Proteins Affects Sarcomere Function

Abstract

Diabetes doubles the risk of developing heart failure, independent of coronary artery disease and hypertension. The mechanisms connecting these two diseases are poorly understood, although we have previously shown one connection is likely due to methylglyoxal (MGO), a highly reactive glycolysis byproduct that can irreversibly modify lysine (K) and arginine (R) residues in a process called glycation. We found MGO glycation of the myofilament decreased calcium sensitivity and maximum calcium activated force in diabetes. Here we hypothesized MGO may further impact function by competing for lysine residues that would otherwise be targets for acetylation, which has been shown to impact cardiac function. To assess this hypothesis, non-failing human left ventricular (LV) myocardial tissue was exposed to MGO (100 μM) or vehicle and then the treated with acetic anhydride in acetonitrile (300 μM, Ac 2 O-ACN) overnight. Ac 2 O-ACN increased myofilament protein acetylation in both groups, but this effect was greatly reduced in samples pre-treated with MGO, suggesting these two PTMs do compete for a subset of lysine residues. To discover the specific sites of this acetylation-glycation crosstalk, we compared mass spectrometry data sets from diabetic humans, MGO treated mouse myocytes, and acetylated myocytes, which revealed sites of crosstalk on actin, myosin, and myosin light chains - proteins essential for normal contractile function. Importantly, these glycation-acetylation crosstalk sites were found in human samples and the data suggest the balance of these may change in disease states. To explore the functional consequence(s) of this crosstalk, we incubated human LV isolated skinned myocytes with Ac 2 O-ACN (300 μM, overnight), which enhanced function by significantly increasing calcium sensitivity. However, pre-treatment with MGO (100 μM) completely blocked this functional effect of acetylation. Together, these data demonstrate that glycation and acetylation compete for certain myofilament lysine residues, and that glycation can block the beneficial functional effects of acetylation. These results provide insight into the molecular mechanisms behind diabetic cardiomyopathy and the utility of targeting acetylation clinically.