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Epidermal growth factor stimulates serine/threonine phosphorylation of the focal adhesion protein paxillin in a MEK‐dependent manner in normal rat kidney cells
Author(s) -
Terfera David R.,
Brown Michael C.,
Turner Christopher E.
Publication year - 2002
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.10082
Subject(s) - paxillin , ptk2 , focal adhesion , microbiology and biotechnology , epidermal growth factor , phosphorylation , protein kinase c , biology , kinase , chemistry , mitogen activated protein kinase kinase , biochemistry , receptor
Epidermal growth factor (EGF)‐stimulated proliferation of renal epithelial cells plays an important role in the recovery of kidney tubule epithelia following exposure to insult. Numerous studies have demonstrated that tyrosine phosphorylation of the focal adhesion protein paxillin mediates in part the effects of growth factors on cell growth, migration, and organization of the actin‐based cytoskeleton. The experiments in this report were designed to determine the effect of EGF on paxillin phosphorylation in normal rat kidney (NRK) epithelial cells. Interestingly, treatment of NRK cells with EGF stimulated paxillin serine/threonine phosphorylation, which caused a reduction in the mobility of paxillin on sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE). The EGF‐stimulated mobility shift of paxillin was independent of an intact cytoskeleton, phosphatidylinositol 3‐kinase (PI 3‐kinase) activation, protein kinase C (PKC) activation, and cellular adhesion. However, inhibitors of the mitogen‐activated protein kinase/extracellular signal‐regulated kinase kinase abrogated the EGF‐stimulated change in paxillin mobility. In addition, the EGF‐stimulated change in paxillin serine/threonine phosphorylation was not accompanied by a profound reorganization of the actin cytoskeleton. These results identify paxillin as a component EGF signaling in renal epithelial cells and implicate members of the MAP kinase pathway as critical regulators of paxillin serine/threonine phosphorylation. J. Cell. Physiol. 191: 82–94, 2002. © 2002 Wiley‐Liss, Inc.