title: Epidermal growth factor stimulates Rac activation through Src and phosphatidylinositol 3-kinase to promote colonic epithelial cell migration.
abstract: Regulated intestinal epithelial cell migration plays a key role in wound healing and maintenance of a healthy gastrointestinal tract. Epidermal growth factor (EGF) stimulates cell migration and wound closure in intestinal epithelial cells through incompletely understood mechanisms. In this study we investigated the role of the small GTPase Rac in EGF-induced cell migration using an in vitro wound-healing assay. In mouse colonic epithelial (MCE) cell lines, EGF-stimulated wound closure was accompanied by a doubling of the number of cells containing lamellipodial extensions at the wound margin, increased Rac membrane translocation in cells at the wound margin, and rapid Rac activation. Either Rac1 small interfering (si)RNA or a Rac1 inhibitor completely blocked EGF-stimulated wound closure. Whereas EGF failed to activate Rac in colon cells from EGF receptor (EGFR) knockout mice, stable expression of wild-type EGFR restored EGF-stimulated Rac activation and migration. Pharmacological inhibition of either phosphatidylinositol 3-kinase (PI3K) or Src family kinases reduced EGF-stimulated Rac activation. Cotreatment of cells with both inhibitors completely blocked EGF-stimulated Rac activation and localization to the leading edge of cells and lamellipodial extension. Our results present a novel mechanism by which the PI3K and Src signaling cascades cooperate to activate Rac and promote intestinal epithelial cell migration downstream of EGFR.
authors.affiliation: Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232-0696, USA.
authors.forename: Rebecca S
authors.initials: RS
authors.lastname: Dise
authors.forename: Mark R
authors.initials: MR
authors.lastname: Frey
authors.forename: Robert H
authors.initials: RH
authors.lastname: Whitehead
authors.forename: D Brent
authors.initials: DB
authors.lastname: Polk
mesh_terms: D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects; D003106:Colon / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000378:metabolism; D004847:Epithelial Cells / Q000201:enzymology / Q000378:metabolism*; D066246:ErbB Receptors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009479:Neuropeptides / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D021381:Protein Transport; D011554:Pseudopodia / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection; D014945:Wound Healing / Q000187:drug effects; D020744:rac GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D009479:Neuropeptides; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D034741:RNA, Small Interfering; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein; D019061:src-Family Kinases; C484602:Rac1 protein, mouse