N~ε-lysine acetylation determines dissociation from GAP junctions and lateralization of connexin 43 in normal and dystrophic heart

摘要

Wanting to explore the epigenetic basis of Duchenne cardiomyop-athy, we found that global histone acetylase activity was abnormally elevated and the acetylase P3007CBP-associated factor (PCAF) coimmunoprecipitated with connexin 43 (Cx43), which was N~ε-ly-sine acetylated and lateralized in mdx heart. This observation was paralleled by Cx43 dissociation from W-cadherin and zonula occlu-dens 1, whereas pp60-c-Src association was unaltered. In vivo treatment of mdx with the pan-histone acetylase inhibitor anacardic acid significantly reduced Cx43 N~ε-lysine acetylation and restored its association to GAP junctions (GJs) at intercalated discs. Noteworthy, in normal as well as mdx mice, the class Ha histone deacetylases 4 and 5 constitutively colocalized with Cx43 either at GJs or in the lateralized compartments. The class I histone deacetylase 3 was also part of the complex. Treatment of normal controls with the histone deacetylase pan-inhibitor suberoylanilide hydroxamic acid (MC1568) or the class lla-selective inhibitor 3-{4-[3-(3-fluorophenyl)-3-oxo-1 -propen-1 -yl]-1 -methyl-1 H-pyrrol-2-yl}-N-hydroxy-2-propenamide (MC1568) determined Cx43 hyperacetylation, dissociation from GJs, and distribution along the long axis of ventricular cardiomyocytes. Consistently, the histone acetylase activator pentadecylidenemalo-nate 1b (SPV106) hyperacetylated cardiac proteins, including Cx43, which assumed a lateralized position that partly reproduced the dystrophic phenotype. In the presence of suberoylanilide hydroxamic acid, cell to cell permeability was significantly diminished, which is in agreement with a Cx43 close conformation in the consequence of hyperacetylation. Additional experiments, performed with Cx43 acetylation mutants, revealed, for the acetylated form of the molecule, a significant reduction in plasma membrane localization and a tendency to nuclear accumulation. These results suggest that Cx43 N~ε-lysine acetylation may have physiopathological consequences for cell to cell coupling and cardiac function.