A proposed role for ZO-1 in targeting connexin 43 gap junctions to the endocytic pathway.
Gap junctions are intercellular channels organized in plaque that directly link adjacent cells. Connexins (Cx), the constitutive proteins of gap junctions are associated with several partner proteins (cytoskeletal, anchoring) which could participate in plaque formation and degradation. Coimmunoprecipitation and indirect immunofluorescence analyses showed that ZO-1, a tight junction-associated protein, was linked to Cx43 in the testis. By using gamma-hexachlorocyclohexane (HCH), known to induce gap junction endocytosis, we demonstrated that endocytosis increased Cx43/ZO-1 association within the cytoplasm of treated Sertoli cells. In control cells, the two proteins were present, as expected, at the plasma membrane level, but poorly colocalized. The increased intracytoplasmic Cx43/ZO-1 complex was associated with a shift towards increased levels of Cx43 P1 and P2 isoforms. The HCH induced Cx43 hyperphosphorylation was abolished by the ERK inhibitor PD98059 suggesting that this effect could be mediated through activation of the ERK pathway. These data strongly support a novel role for ZO-1 in the turnover of Cx43 during gap junction plaque endocytosis.
Segretain
D
D
Inserm EMI 00-09, IFR 50, Université Paris V, 45, rue des Saint-Pères, 75006 Paris, France.
Fiorini
C
C
Decrouy
X
X
Defamie
N
N
Prat
J R
JR
Pointis
G
G
D000818:Animals; D018031:Connexin 43 / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism / Q000473:pathology; D004705:Endocytosis; D005419:Flavonoids / Q000494:pharmacology; D017629:Gap Junctions / Q000378:metabolism*; D001556:Hexachlorocyclohexane / Q000494:pharmacology; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D020033:Protein Isoforms; D021381:Protein Transport; D051381:Rats; D012708:Sertoli Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D015398:Signal Transduction; D013737:Testis / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D019108:Tight Junctions; D062826:Zonula Occludens-1 Protein
D018031:Connexin 43; D005419:Flavonoids; D008565:Membrane Proteins; D010750:Phosphoproteins; D020033:Protein Isoforms; C569044:Tjp1 protein, rat; D062826:Zonula Occludens-1 Protein; D001556:Hexachlorocyclohexane; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one