Effects of 18-glycyrrhetinic acid on serine 368 phosphorylation of connexin43 in rat neonatal cardiomyocytes.
18Beta-glycyrrhetinic acid (18beta-GA) regulates serine/threonine dephosphorylation of connexin43 (Cx43). Phospho-specific antibodies were used here to determine the effect of 18beta-GA on serine 368-phosphorylated Cx43 (pSer368Cx43) in cultured rat neonatal cardiomyocytes by immunofluorescence microscopy and immunoblot analyses. 18beta-GA caused a time-dependent increase in pSer368Cx43 levels and induced gap junction disassembly, shown by a change in pSer368Cx43 immunostaining from large aggregates to dispersed punctates at cell-cell contact areas. 18beta-GA also induced a time-dependent increase in the levels of serine 729-phosphorylated PKCepsilon, the active form of PKCepsilon. The 18beta-GA-induced increase in pSer368Cx43 levels and changes in pSer368Cx43 staining pattern were abolished by the PKC inhibitor, chelerythrine. Furthermore, 18beta-GA increased the co-immunoprecipitation of Cx43 with PKCepsilon. However, the 18beta-GA-induced increase in pSer368Cx43 levels and increased association of Cx43 with PKCepsilon were inhibited by co-treatment with the protein phosphatase type 1 and type 2A inhibitor, calyculin A. We conclude that 18beta-GA induces Ser368 phosphorylation of Cx43 via PKCepsilon.
Liang
Jyun-Yan
JY
Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei, Taiwan.
Wang
Seu-Mei
SM
Chung
Tun-Hui
TH
Yang
Shih-Hung
SH
Wu
Jiahn-Chun
JC
D000595:Amino Acid Sequence / Q000187:drug effects / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D053119:Benzophenanthridines / Q000494:pharmacology; D002478:Cells, Cultured; D018031:Connexin 43 / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D017629:Gap Junctions / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D006034:Glycyrrhetinic Acid / Q000494:pharmacology*; D007150:Immunohistochemistry; D008297:Male; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D010766:Phosphorylation / Q000187:drug effects; D051744:Protein Kinase C-epsilon / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012694:Serine / Q000737:chemistry / Q000378:metabolism; D013997:Time Factors; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
D000893:Anti-Inflammatory Agents; D000970:Antineoplastic Agents; D053119:Benzophenanthridines; D018031:Connexin 43; D004791:Enzyme Inhibitors; D012694:Serine; C016299:chelerythrine; D051744:Protein Kinase C-epsilon; D006034:Glycyrrhetinic Acid