title: Molecular reorganization of Cx43, Zo-1 and Src complexes during the endocytosis of gap junction plaques in response to a non-genomic carcinogen.
abstract: The gap junction protein connexin 43 (Cx43) exhibits dynamic trafficking that is altered in most tumor cells and in response to carcinogen exposure. A number of connexin (Cx)-binding proteins are known to be involved in endocytic internalization of gap junctions. Here, we analyzed the discrete molecular interactions that occur between Src, ZO-1 and Cx43 during Cx43 internalization in response to the non-genomic carcinogen gamma-hexachlorocyclohexane (HCH). Internalization of the Cx43 gap junction plaque was significantly accelerated in Cx43-GFP transfected 42GPA9 Sertoli cells that were exposed to the carcinogen. HCH induced the rapid recruitment of Src to the plasma membrane, activation of Src within 3 minutes and the efficient inhibition of gap junctional coupling, but had no effect in the presence of the Src inhibitor PP2. Immunoprecipitation experiments demonstrated that HCH increased Cx43-Src interaction and concomitantly decreased Cx43-ZO-1 association. ZO-1 was detected on both sides of the gap junction plaques in untreated cells, but appeared to be mainly localized on one side during HCH-induced internalization. The dissociation of ZO-1 from Cx43 appears to occur specifically on the side of the plaque to which Src was recruited. These findings provide mechanistic evidence by which internalization of the Cx43 gap junction plaque might be initiated, suggesting that Src-mediated dissociation of ZO-1 from one side of the plaque initiates endocytic internalization of gap junctions and that this process is amplified in response to exposure to HCH.
authors.affiliation: INSERM U 895, Team 5 Physiopathologic control of germ cell proliferation: genomic and non genomic mechanisms, Université Paris Descartes, 45 rue des Saint-Pères, 75006, Paris, France.
authors.forename: Jérome
authors.initials: J
authors.lastname: Gilleron
authors.forename: Céline
authors.initials: C
authors.lastname: Fiorini
authors.forename: Diane
authors.initials: D
authors.lastname: Carette
authors.forename: Christiane
authors.initials: C
authors.lastname: Avondet
authors.forename: Matthias M
authors.initials: MM
authors.lastname: Falk
authors.forename: Dominique
authors.initials: D
authors.lastname: Segretain
authors.forename: Georges
authors.initials: G
authors.lastname: Pointis
mesh_terms: D000818:Animals; D002273:Carcinogens / Q000494:pharmacology*; D002460:Cell Line; D018031:Connexin 43 / Q000235:genetics / Q000378:metabolism*; D004705:Endocytosis / Q000187:drug effects; D017629:Gap Junctions / Q000187:drug effects / Q000378:metabolism*; D001556:Hexachlorocyclohexane / Q000494:pharmacology*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism*; D012708:Sertoli Cells / Q000187:drug effects / Q000378:metabolism; D062826:Zonula Occludens-1 Protein
chemical_list: D002273:Carcinogens; D018031:Connexin 43; D008565:Membrane Proteins; D010750:Phosphoproteins; D062826:Zonula Occludens-1 Protein; D001556:Hexachlorocyclohexane; D016392:Proto-Oncogene Proteins pp60(c-src)