title: p190A RhoGAP is a glycogen synthase kinase-3-beta substrate required for polarized cell migration.
abstract: The Rho GTPases are critical regulators of the actin cytoskeleton and are required for cell adhesion, migration, and polarity. Among the key Rho regulatory proteins in the context of cell migration are the p190 RhoGAPs (p190A and p190B), which function to modulate Rho signaling in response to integrin engagement. The p190 RhoGAPs undergo complex regulation, including phosphorylation by several identified kinases, interactions with phospholipids, and association with a variety of cellular proteins. Here, we have identified an additional regulatory mechanism unique to p190A RhoGAP that involves priming-dependent phosphorylation by glycogen synthase-3-beta (GSK-3beta), a kinase previously implicated in establishing cell polarity. We found that p190A-deficient fibroblasts exhibit a defect in directional cell migration reflecting a requirement for GSK-3beta-mediated phosphorylation of amino acids in the C-terminal "tail" of p190A. This phosphorylation leads to inhibition of p190A RhoGAP activity in vitro and in vivo. These studies identify p190A as a novel GSK-3beta substrate and reveal a mechanism by which GSK-3beta contributes to cellular polarization in directionally migrating cells via effects on Rho GTPase activity.
authors.affiliation: Massachusetts General Hospital Cancer Center and Harvard Medical School, Charlestown, MA 02129, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Jiang
authors.forename: Martha
authors.initials: M
authors.lastname: Betson
authors.forename: Roseann
authors.initials: R
authors.lastname: Mulloy
authors.forename: Rosemary
authors.initials: R
authors.lastname: Foster
authors.forename: Magdolna
authors.initials: M
authors.lastname: Lévay
authors.forename: Erzsébet
authors.initials: E
authors.lastname: Ligeti
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Settleman
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002465:Cell Movement; D002522:Chlorocebus aethiops; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D005347:Fibroblasts / Q000378:metabolism; D020690:GTPase-Activating Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D038362:Glycogen Synthase Kinase 3 / Q000737:chemistry*; D000071679:Glycogen Synthase Kinase 3 beta; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D012097:Repressor Proteins / Q000378:metabolism / Q000502:physiology*; D017386:Sequence Homology, Amino Acid
chemical_list: C513041:Arhgap35 protein, mouse; D004268:DNA-Binding Proteins; D020690:GTPase-Activating Proteins; D012097:Repressor Proteins; C085379:rho GTPase-activating protein; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D038362:Glycogen Synthase Kinase 3