Membrane Cholesterol Regulate The Expression And Distribution Of Cardiac Connexin43via PKC Pathway

Cholesterol can modulate activity of protein kinase C, and PKC can phosphorylate connexin43to regulate its function, respectively. However, it is not known whether cholesterol could modulate function of Cx43through the PKC-dependent pathway. In the present study, we demonstrated that cholesterol enrichment reduced the dye transfer ability of Cx43in cultured H9c2cells. Western blot analysis indicated that cholesterol enrichment upregulated the Cx43expression and enhanced phosphorylated state of Cx43. Immunofluorescent images showed that cholesterol enrichment made the Cx43distribution from condensed to diffused manner in the interface between the cells. In cholesterol enriched cells, PKC antagonists partially restored the dye transfer ability among the cells, downregulated the phosphorylation of Cx43and redistributed Cx43from the diffused manner to the condensed manner in the cell interface. In addition, reduction of cholesterol level suppressed PKC activity to phosphorylate Cx43and restored Cx43function in PKC agonist-treated cells. Furthermore, we demonstrated that cholesterol enrichment upregulated the phosphorylated state of Cx43at Ser368, while PKC antagonists reversed the effect. Taken together, cholesterol level in the cells plays important roles in regulating Cx43function through activation of the PKC signaling pathway.