Cadherin mediated cell-cell adhesion is regulated by tyrosine phosphatases in human keratinocytes.
Normal Human Keratinocytes express on their cell surface E- and P-cadherins, two Ca2+ dependent homophilic cell adhesion molecules that mediate keratinocyte-keratinocyte adherens junctions. In other cell types, adherens-type junctions are reported to be major subcellular targets for tyrosine specific protein phosphorylation (Volberg et al. (1991) Cell Regul., 2, 105-120) involving tyrosine kinases and tyrosine phosphatases. We investigated the role of tyrosine phosphatases in the regulation of cadherin mediated keratinocyte-keratinocyte adhesion. We report the results of a wide tyrosine phosphatase inhibition using pervanadate, a modified vanadate derivative known to inhibit most tyrosine phosphatases. Keratinocytes treated with pervanadate, exhibit an important change in cellular morphology and cadherins/catenins localization as shown by phase contrast microscopy and immunocytochemistry. In this conditions, cadherins and catenins no longer colocalize with the actin cytoskeleton of cells and the amount of E-cadherin bound to the cytoskeleton decreases. A more intense phosphotyrosine labelling is seen at the edges of the treated cells, suggesting that an increase in the phosphorylation rate of some cadherin-catenin complex proteins induces a diminished intercellular adhesion. Finally immunoprecipitation experiments of the E-cadherin/catenin complex from pervanadate treated keratinocytes reveal an increase in the tyrosine phosphorylation rate of E-cadherin, beta catenin and probably gamma catenin. These data suggest an essential role for the protein tyrosine phosphatases in keratinocyte intercellular junctions.
Soler
C
C
IBCP, CNRS UPR 412, Lyon, France.
Rousselle
P
P
Damour
O
O
D000199:Actins / Q000378:metabolism; D015820:Cadherins / Q000502:physiology*; D002118:Calcium / Q000494:pharmacology; D002448:Cell Adhesion; D003599:Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D007365:Intercellular Junctions / Q000378:metabolism*; D015603:Keratinocytes / Q000166:cytology* / Q000201:enzymology; D046911:Macromolecular Substances; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D017027:Protein Tyrosine Phosphatases / Q000502:physiology*; D011505:Protein-Tyrosine Kinases / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014638:Vanadates / Q000494:pharmacology
D000199:Actins; D015820:Cadherins; D046911:Macromolecular Substances; C076715:pervanadate; D014638:Vanadates; D011505:Protein-Tyrosine Kinases; D017027:Protein Tyrosine Phosphatases; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium