Deoxycholic acid differentially regulates focal adhesion kinase phosphorylation: role of tyrosine phosphatase ShP2

Abstract

Khare S, Holgren C, Samarel AM. Deoxycholic acid differentially regulates focal adhesion kinase phosphorylation: role of tyrosine phosphatase ShP2. Am J Physiol Gastrointest Liver Physiol 291: G1100 -G1112, 2006. First published August 17, 2006 doi:10.1152/ajpgi.00008.2006.-Environmental factors, including dietary fats, are implicated in colonic carcinogenesis. Dietary fats modulate secondary bile acids including deoxycholic acid (DCA) concentrations in the colon, which are thought to contribute to the nutritional-related component of colon cancer risk. Here we demonstrate, for the first time, that DCA differentially regulated the sitespecific phosphorylation of focal adhesion kinase (FAK). DCA decreased adhesion of HCA-7 cells to the substratum and induced dephosphorylation of FAK at tyrosine-576/577 (Tyr-576/577) and Tyr-925. Tyrosine phosphorylation of FAK at Tyr-397 remained unaffected by DCA stimulation. Interestingly, we found that c-Src was constitutively associated with FAK and DCA actually activated Src, despite no change in FAK-397 and an inhibition of FAK-576 phosphorylation. DCA concomitantly and significantly increased association of tyrosine phosphatase ShP2 with FAK. Incubation of immunoprecipitated FAK, in vitro, with glutathione-S-transferaseShP2 fusion protein resulted in tyrosine dephosphorylation of FAK in a concentration-dependent manner. Antisense oligodeoxynucleotides directed against ShP2 decreased ShP2 protein levels and attenuated DCA-induced FAK dephosphorylation. Inhibition of FAK by adenoviral-mediated overexpression of FAK-related nonkinase and gene silencing of Shp2 both abolished DCA's effect on cell adhesion, thus providing a possible mechanism for inside-out signaling by DCA in colon cancer cells. Our results suggest that DCA differentially regulates focal adhesion complexes and that tyrosine phosphatase ShP2 has a role in DCA signaling.

Activation of focal adhesion kinase and JNK contributes to the extracellular matrix and cAMP-GEF mediated survival from bile acid induced apoptosis in rat hepatocytes

“…Bile acids can modulate FAK dephosphorylation in colonic epithelial cells (22). We thus examined the effect of GCDC on FAK phosphorylation in hepatocytes plated on CI.…”

“…Normally FAK activation requires binding of integrins to the ECM, mechanistic linkage to the actin cytoskeleton, and autophosphorylation at tyrosine 397 (13,14). In colonic epithelial cells, DCA activates the tyrosine phosphatase, ShP2, leading to FAK dephosphorylation at Tyr 576 and 925 (22). In separate studies in a colon cancer cell line, DCA altered plasma membrane lipid composition leading to increases in membrane cholesterol and decreases in membrane fluidity which resulted in tyrosine phosphorylation of the epidermal growth factor receptor (39).…”

“…Emerging evidence suggests that bile acids may also modulate FAK. In the isolated perfused liver, choleresis associated with infusion of the cytoprotective bile acid, tauroursodeoxycholate (TUDC), is associated with FAK activation and, in colonic epithelial cells, the hepatotoxic bile acid deoxycholate (DCA) dephosphorylates FAK (21,22). The role of FAK in bile acid mediated apoptosis in hepatocytes has not been investigated.…”

Cell density modulates SHC3 expression and survival of human glioblastoma cells through Fak activation

“…Cells were counted on a Z2 Beckman Coulter counter (Beckman Coulter, Cassina De' Pecchi, MI, Italy); before counting, cells in MTS were first disaggregated by trypsin. Transient inhibition of Fak phosphorylation was obtained by treating cells for 24 h with 100 lM sodium deoxycholate (DOC) (Sigma-Aldrich, Milan, Italy) [18] or 2 lM NSC 667249 (FakiI) (Merck-Millipore, Nottingham, UK) [19] or 10 lM PF-573,228 (FakiII) (Merck-Millipore) [20].…”

“…We tested if three Fak inhibitors: sodium deoxycholate (DOC) [18], NSC 667249 (FakiI) [19] and PF-573,228 (FakiII) [20] working with different mechanisms, influenced the levels of Shc3 proteins present in U87-MG growing as MTS or in adherence. Treating U87-MG cells with DOC (24 h, 100 lM) before MTS formation inhibited MTS formation and induced adherence and growth of the cells as a monolayer on bacteriological plastic despite this plastic is usually not permissive for adhesion and growth of U87-MG cells (Fig.…”