title: Akt-mediated GSK-3beta inhibition prevents migration of polyamine-depleted intestinal epithelial cells via Rac1.
abstract: The rapid migration of intestinal epithelial cells (IEC) is important for the healing of mucosal wounds. We have previously shown that polyamine depletion inhibits migration of IEC-6 cells. Akt activation and its downstream target GSK-3beta have been implicated in the regulation of migration. Here we investigated the significance of elevated phosphatidylinositol 3-kinase (PI3K)/Akt signaling on migration of polyamine-depleted cells. Polyamine-depleted cells had high Akt (Ser473) and GSK-3beta (Ser9) phosphorylation. Pretreatment with 20 microM LY294002 (PI3K inhibitor) for 30 min inhibited phosphorylation of Akt, increased migration by activating Rac1 in polyamine-depleted IEC-6 cells, and restored the actin structure similar to that in cells grown in control medium. Treatment of cells with a GSK-3beta inhibitor (AR-A014418) altered the actin cytoskeleton and inhibited migration, mimicking the effects of polyamine depletion. Thus, our results indicate that sustained activation of Akt in response to polyamine depletion inhibits migration through GSK-3beta and Rac1.
authors.affiliation: Department of Physiology, The University of Tennessee Health Science Center, Memphis, TN 38163, USA. rvaidya@physio1.utmem.edu
authors.forename: R J
authors.initials: RJ
authors.lastname: Vaidya
authors.forename: R M
authors.initials: RM
authors.lastname: Ray
authors.forename: L R
authors.initials: LR
authors.lastname: Johnson
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D002465:Cell Movement; D003599:Cytoskeleton / Q000737:chemistry; D004847:Epithelial Cells / Q000166:cytology; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D007413:Intestinal Mucosa / Q000166:cytology*; D007421:Intestine, Small / Q000166:cytology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D011073:Polyamines / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D051381:Rats; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*
chemical_list: D000199:Actins; D038362:Glycogen Synthase Kinase 3; D000071679:Glycogen Synthase Kinase 3 beta; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011073:Polyamines; D051057:Proto-Oncogene Proteins c-akt; D020830:rac1 GTP-Binding Protein; C000605508:Gsk3b protein, rat; C499134:Rac1 protein, rat