Abstract 14286: Crosstalk Between Methylglyoxal and Acetylation Modifications on Actin, Myosin, and Myosin Light Chain Proteins Affects Sarcomere Functionality

Abstract

Diabetes affects ten percent of Americans. Risk of developing heart failure in these patients is doubled, independent of coronary artery disease and hypertension. However, the mechanistic connection between these two diseases is poorly understood. We have shown one connection is likely due to methylglyoxal (MGO), a highly reactive glycolysis product that can irreversibly modify lysine and arginine residues, a process called glycation. Moreover, we found MGO glycation of the myofilament decreased both calcium sensitivity and maximum calcium activated force (Fmax). Here, we hypothesized that MGO may also negatively impact function by competing for lysine residues that would otherwise be targets for acetylation, which has been shown to be beneficial to cardiac function. Using non-failing human left ventricular (LV) myocardial tissue that had been exposed to acute treatment of MGO (500 μM) or vehicle and subsequently treated with a high dose of acetic anhydride in acetonitrile (300μM) overnight, we found that compared to the vehicle treated samples, MGO inhibited overall acetylation, suggesting that these two PTMs do compete for a subset of lysine residues in the heart. Next, we compared mass spectrometry data sets from diabetic humans, MGO treated mouse myocytes, and acetylated myocytes to identify the specific overlapping residues that acetylation and glycation compete for. This analysis identified multiple sites of crosstalk on actin, myosin, and myosin light chains - proteins essential for normal contractile function. Our preliminary data support a contractile consequence to this crosstalk. Incubation of mouse LV isolated skinned myocytes with acetic anhydride in acetonitrile (300μM, overnight) increased both calcium sensitivity and Fmax. However, exposure to MGO first (500μM) blocked these beneficial functions acetylation (300μM, overnight) in mouse myocytes. Together, we believe these data demonstrate that glycation and acetylation do compete for residues in the myofilament, and that glycation is capable of blocking the beneficial functional effects of protein acetylation. If these results are confirmed and extended in vivo, they could have important consequences in diabetes and in the utility of using HDAC inhibitors clinically.