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Transactivation of the epidermal growth factor receptor mediates muscarinic stimulation of focal adhesion kinase in intestinal epithelial cells
Author(s) -
Calandrella Sean O.,
Barrett Kim E.,
Keely Stephen J.
Publication year - 2005
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.20190
Subject(s) - focal adhesion , paxillin , ptk2 , microbiology and biotechnology , phosphorylation , proto oncogene tyrosine protein kinase src , tyrosine phosphorylation , chemistry , actin cytoskeleton , transactivation , cytochalasin d , signal transduction , cancer research , epidermal growth factor , biology , protein kinase a , cytoskeleton , receptor , biochemistry , mitogen activated protein kinase kinase , cell , transcription factor , gene
We have previously shown that the G q protein coupled receptor (G q PCR) agonist, carbachol (CCh), transactivates and recruits epidermal growth factor receptor (EGFr)‐dependent signaling mechanisms in intestinal epithelial cells. Increasing evidence suggests that G q PCR agonists can also recruit focal adhesion‐dependent signaling pathways in some cell types. Therefore, the aim of the present study was to investigate if CCh stimulates activation of the focal adhesion‐associated protein, focal adhesion kinase (FAK), in intestinal epithelia and, if so, to examine the signaling mechanisms involved. Experiments were carried out on monolayers of T 84 cells grown on permeable supports. CCh rapidly induced tyrosine phosphorylation of FAK in T 84 cells. This effect was accompanied by phosphorylation of another focal adhesion‐associated protein, paxillin, and association of FAK with paxillin. CCh‐stimulated FAK phosphorylation was inhibited by a chelator of intracellular Ca 2+ , BAPTA/AM (20 μM), and was mimicked by thapsigargin (2 μM), which mobilizes intracellular Ca 2+ in a receptor‐independent fashion. CCh also induced association of FAK with the EGFr and FAK phosphorylation was attenuated by an EGFr inhibitor, tyrphostin AG1478, and an inhibitor of Src family kinases, PP2. The actin cytoskeleton disruptor, cytochalasin D (20 μM), abolished FAK phosphorylation in response to CCh but did not alter CCh‐induced EGFr or ERK MAPK activation. In summary, these data demonstrate that agonists of G q PCRs have the ability to induce FAK activation in intestinal epithelial cells. G q PCR‐induced FAK activation is mediated by via a pathway involving transactivation of the EGFr and alterations in the actin cytoskeleton. © 2004 Wiley‐Liss, Inc.