title: Transforming growth factor-beta stimulates intestinal epithelial focal adhesion kinase synthesis via Smad- and p38-dependent mechanisms.
abstract: Focal adhesion kinase (FAK) regulates cell migration, proliferation, and apoptosis. FAK protein is reduced at the edge of migrating gut epithelial sheets in vitro, but it has not been characterized in restitutive gut mucosa in vivo. Here we show that FAK and activated phospho-FAK (FAK(397)) immunoreactivity was lower in epithelial cells immediately adjacent to human gastric and colonic ulcers in vivo, but dramatically increased in epithelia near the ulcers, possibly reflecting stimulation by growth factors absent in vitro. Transforming growth factor (TGF)-beta, but not fibroblast growth factor, platelet-derived growth factor, or vascular endothelial growth factor, increased FAK levels in Caco-2 and IEC-6 cells. Epithelial immunoreactivity to TGF-beta and phospho-Smad3 was also higher near the ulcers, varying in parallel with FAK. The TGF-beta receptor antagonist SB431542 completely blocked TGF-beta-induced Smad2/3 and p38 activation in IEC-6 cells. SB431542, the p38 antagonist SB203580, and siRNA-mediated reduction of Smad2 and p38alpha prevented TGF-beta stimulation of both FAK transcription and translation (as measured via a FAK promoter-luciferase construct). FAK(397) levels were directly related to total FAK protein expression. Although gut epithelial motility is associated with direct inhibition of FAK protein adjacent to mucosal wounds, TGF-beta may increase FAK protein near but not bordering mucosal ulcers via Smad2/3 and p38 signals. Our results show that regulation of FAK expression may be as important as FAK phosphorylation in critically influencing gut epithelial cell migration after mucosal injury.
authors.affiliation: Departments of Surgery and Pathology, John D. Dingell VA Medical Center, Wayne State University, 4646 John R Detroit, MI 48201-1932, USA.
authors.forename: Mary F
authors.initials: MF
authors.lastname: Walsh
authors.forename: Dinakar R
authors.initials: DR
authors.lastname: Ampasala
authors.forename: James
authors.initials: J
authors.lastname: Hatfield
authors.forename: Richard
authors.initials: R
authors.lastname: Vander Heide
authors.forename: Silke
authors.initials: S
authors.lastname: Suer
authors.forename: Arun K
authors.initials: AK
authors.lastname: Rishi
authors.forename: Marc D
authors.initials: MD
authors.lastname: Basson
mesh_terms: D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D002460:Cell Line; D002465:Cell Movement; D004149:Dioxoles / Q000494:pharmacology; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000096:biosynthesis*; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism*; D048308:Mitogen-Activated Protein Kinase 14 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction; D051899:Smad2 Protein / Q000378:metabolism*; D051900:Smad3 Protein / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000494:pharmacology / Q000502:physiology*
chemical_list: C459179:4-(5-benzo(1,3)dioxol-5-yl-4-pyridin-2-yl-1H-imidazol-2-yl)benzamide; D001549:Benzamides; D004149:Dioxoles; D007093:Imidazoles; D011725:Pyridines; D018125:Receptors, Transforming Growth Factor beta; C497790:SMAD3 protein, human; D051899:Smad2 Protein; C497784:Smad2 protein, rat; D051900:Smad3 Protein; D016212:Transforming Growth Factor beta; D051416:Focal Adhesion Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D048308:Mitogen-Activated Protein Kinase 14; D000077293:Receptor, Transforming Growth Factor-beta Type I; C000625843:Tgfbr1 protein, rat; C093642:SB 203580