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Integrin-dependent PLC-gamma1 phosphorylation mediates fibronectin-dependent adhesion.
Tvorogov, Denis; Wang, Xue-Jie; Zent, Roy; Carpenter, Graham.
Afiliación
  • Tvorogov D; Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
J Cell Sci ; 118(Pt 3): 601-10, 2005 Feb 01.
Article en En | MEDLINE | ID: mdl-15657076
Although integrin engagement initiates signaling events such as focal-adhesion kinase (FAK) and Src kinase activation, the role of phosphoinositide turnover in cell adhesion is less clear. To assess PLC-gamma1 function in this process, Plcg1(-/-) fibroblasts (Null) were compared with the same fibroblasts in which PLC-gamma1 was re-expressed (Null+). Following plating on fibronectin, Null cells displayed a significantly impaired rate of adhesion compared with Null+ cells. This defect was detected at low concentrations of fibronectin; at high fibronectin concentrations, the Null and Null+ cells displayed equivalent adhesion characteristics. The differences were not due to PLC-gamma1-dependent changes in integrin subunit expression, nor was integrin receptor clustering impaired with the absence of PLC-gamma1. Experiments with site-specific antibodies and PLC-gamma1 mutants showed that fibronectin selectively increased phosphorylation of Tyr783 and that mutagenesis of this residue, but not Tyr771 or Tyr1253, abrogated fibronectin-dependent adhesion. The SH2 domains of PLC-gamma1 were also required for maximal adhesion on fibronectin. Adhesion to fibronectin induced PLC-gamma1 tyrosine phosphorylation that was inhibited by a Src-kinase inhibitor, but not an epidermal-growth-factor-receptor kinase inhibitor. Moreover, in cells null for Src family members, but not in cells null for FAK family members, integrin-dependent PLC-gamma1 tyrosine phosphorylation was greatly reduced. Finally, the data demonstrated that PLC-gamma1 co-immunoprecipitated with Src following fibronectin-induced integrin activation, and this association did not depend on FAK expression.
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Banco de datos: MEDLINE Asunto principal: Fosfolipasas de Tipo C / Integrinas / Adhesión Celular / Fibronectinas Límite: Animals Idioma: En Revista: J Cell Sci Año: 2005 Tipo del documento: Article País de afiliación: Estados Unidos
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Banco de datos: MEDLINE Asunto principal: Fosfolipasas de Tipo C / Integrinas / Adhesión Celular / Fibronectinas Límite: Animals Idioma: En Revista: J Cell Sci Año: 2005 Tipo del documento: Article País de afiliación: Estados Unidos