title: 18beta-glycyrrhetinic acid promotes src interaction with connexin43 in rat cardiomyocytes.
abstract: The mechanism by which 18beta-glycyrrhetinic acid regulates gap junction intercellular communication (GJIC) remains poorly understood. In this study, treatment of cultured rat neonatal cardiomyocytes with 18beta-glycyrrhetinic acid resulted in dose-dependent inhibition of GJIC as assessed by fluorescent dye transfer analysis. 18beta-Glycyrrhetinic acid induced time-dependent serine/threonine dephosphorylation and redistribution of connexin43 (Cx43) in cardiomyocytes and the induced Cx43 dephosphorylation was prevented by the protein phosphatase inhibitor, calyculin A. However, functional analyses showed that the inhibitory effect of 18beta-glycyrrhetinic acid on dye spreading among cardiomyocytes was not blocked by calyculin A, but was blocked by the Src-selective tyrosine kinase inhibitor, PP2. 18beta-Glycyrrhetinic acid also induced an increase in the levels of phosphorylated Src, and this effect was prevented by PP2. Immunoprecipitation using anti-Cx43 and anti-p-Src antibodies showed that 18beta-glycyrrhetinic acid increased the association between p-Src and Cx43 and induced tyrosine phosphorylation of Cx43. We conclude that the inhibitory effect of 18beta-glycyrrhetinic acid on GJIC in cardiomyocytes involves Src-mediated tyrosine phosphorylation of Cx43.
authors.affiliation: Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Tun-Hui
authors.initials: TH
authors.lastname: Chung
authors.forename: Seu-Mei
authors.initials: SM
authors.lastname: Wang
authors.forename: Yun-Chieh
authors.initials: YC
authors.lastname: Chang
authors.forename: Yuh-Lien
authors.initials: YL
authors.lastname: Chen
authors.forename: Jiahn-Chun
authors.initials: JC
authors.lastname: Wu
mesh_terms: D000818:Animals; D002450:Cell Communication / Q000187:drug effects; D002478:Cells, Cultured; D018031:Connexin 43 / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D017629:Gap Junctions / Q000187:drug effects; D006034:Glycyrrhetinic Acid / Q000494:pharmacology*; D009206:Myocardium / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D018031:Connexin 43; D016392:Proto-Oncogene Proteins pp60(c-src); D006034:Glycyrrhetinic Acid