Soler C, Rousselle P, Damour O
IBCP, CNRS UPR 412, Lyon, France.
Cell Adhes Commun. 1998 Jan;5(1):13-25. doi: 10.3109/15419069809005595.
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.
正常人类角质形成细胞在其细胞表面表达E-钙黏蛋白和P-钙黏蛋白，这两种Ca2+依赖性同源性细胞黏附分子介导角质形成细胞-角质形成细胞黏附连接。在其他细胞类型中，据报道黏附型连接是酪氨酸特异性蛋白磷酸化的主要亚细胞靶点（Volberg等人，《细胞调控》，1991年，第2卷，第105 - 120页），涉及酪氨酸激酶和酪氨酸磷酸酶。我们研究了酪氨酸磷酸酶在调节钙黏蛋白介导的角质形成细胞-角质形成细胞黏附中的作用。我们报告了使用过氧钒酸盐进行广泛酪氨酸磷酸酶抑制的结果，过氧钒酸盐是一种已知可抑制大多数酪氨酸磷酸酶的改良钒酸盐衍生物。用过氧钒酸盐处理的角质形成细胞，通过相差显微镜和免疫细胞化学显示，细胞形态和钙黏蛋白/连环蛋白定位发生了重要变化。在这种情况下，钙黏蛋白和连环蛋白不再与细胞的肌动蛋白细胞骨架共定位，并且与细胞骨架结合的E-钙黏蛋白量减少。在处理过的细胞边缘可见更强烈的磷酸酪氨酸标记，表明某些钙黏蛋白-连环蛋白复合蛋白磷酸化率的增加导致细胞间黏附减弱。最后，对用过氧钒酸盐处理的角质形成细胞的E-钙黏蛋白/连环蛋白复合物进行免疫沉淀实验，结果显示E-钙黏蛋白、β-连环蛋白以及可能的γ-连环蛋白的酪氨酸磷酸化率增加。这些数据表明蛋白酪氨酸磷酸酶在角质形成细胞细胞间连接中起着重要作用。
