Interplay between PKC and the MAP kinase pathway in Connexin43 phosphorylation and inhibition of gap junction intercellular communication.
Gap junction channels are made of a family proteins called connexins. The best-studied type of connexin, Connexin43 (Cx43), is phosphorylated at several sites in its C-terminus. The tumor-promoting phorbol ester TPA strongly inhibits Cx43 gap junction channels. In this study we have investigated mechanisms involved in TPA-induced phosphorylation of Cx43 and inhibition of gap junction channels. The data show that TPA-induced inhibition of gap junction intercellular communication (GJIC) is dependent on both PKC and the MAP kinase pathway. The data suggest that PKC-induced activation of MAP kinase partly involves Src-independent trans-activation of the EGF receptor, and that TPA-induced shift in SDS-PAGE gel mobility of Cx43 is caused by MAP kinase phosphorylation, whereas phosphorylation of S368 by PKC does not alter gel migration of Cx43. We also show that TPA, in addition to phosphorylation of S368, also induces phosphorylation of S255 and S262, in a MAP kinase-dependent manner. The data add to our understanding of the molecular mechanisms involved in the interplay between signaling pathways in regulation of GJIC.
Sirnes
Solveig
S
Department of Cancer Prevention, Institute for Cancer Research, Norwegian Radium Hospital, Montebello, Oslo, Norway.
Kjenseth
Ane
A
Leithe
Edward
E
Rivedal
Edgar
E
D000818:Animals; D002450:Cell Communication / Q000187:drug effects*; D002460:Cell Line; D018031:Connexin 43 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism; D017629:Gap Junctions / Q000187:drug effects* / Q000378:metabolism; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D018031:Connexin 43; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D011493:Protein Kinase C; D020929:Mitogen-Activated Protein Kinase Kinases; D013755:Tetradecanoylphorbol Acetate