Abstract 10140: Lysine Acetylation Determines Dissociation From GAP-Junctions and Lateralization of Connexin 43 in Normal and Dystrophic Heart.
Introduction: In the mdx mouse model of Duchenne muscular dystrophy, under stress condition, severe ventricular arrhythmias are present and connexin 43 (Cx43) is mostly lateralized.
Methods & Results: In this context the expression and activity of the histone acetylase (HAT) PCAF was found elevated and co-immunoprecipitated with a lysine-acetylated form of Cx43. The in vivo treatment with the pan-HAT inhibitor anacardic acid (ANAC) normalized Cx43 acetylation levels and restored the appropriate localization to GAP-junctions (GJ). Conversely, a short-term treatment (72–96 hours) of normal control mice with the histone deacetylase (HDAC) pan-inhibitor suberoylanilide hydroxamic acid (SAHA)or the HAT activator SPV106 determined Cx43 hyperacetylation, dissociation from GJ and distribution along the lateral membrane of ventricular cardiomyocytes. In this condition, epicardial multiple lead recording revealed the presence of higher excitability and decreased conduction velocity along the fibers suggesting that lysine acetylation may be an important post-transduction modification (PTM) with consequences on cardiac Cx43 distribution and function. Mechanistically we found that, in normal and dystrophic hearts, lysine acetylation created a Cx43 association with an acetylated and phosphorylated form of pp60-SRC (cSRC) promoting dissociation from the GJ proteins zonula occludens-1 (ZO1) and N-cadherin (NCAD). One of the cSRC substrates on Cx43, the tyrosine 265, was found heavily phosphorylated while phosphorylation at residue 262, substrate of CDK1, was significantly decreased. Intriguingly, the in-silico prediction of acetylated lysine residues performed through the PHOSIDA web site (www.phosida.org) identified at least three highly conserved Cx43 lysines at position 9, 234 and 264 as putative acetylation targets.
Conclusions: Taken altogether our results suggest that lysine acetylation could alter Cx43 affinity to cSRC having a negative impact on that for GJ components. These findings provide the first evidence that lysine acetylation may have a role in Cx43 spatial distribution and/or complex formation with potential consequences for electrical impulse propagation and cardiac function.
- © 2010 by American Heart Association, Inc.