title: FilGAP, a Rho- and ROCK-regulated GAP for Rac binds filamin A to control actin remodelling.
abstract: FilGAP is a newly recognized filamin A (FLNa)-binding RhoGTPase-activating protein. The GTPase-activating protein (GAP) activity of FilGAP is specific for Rac and FLNa binding targets FilGAP to sites of membrane protrusion, where it antagonizes Rac in vivo. Dominant-negative FilGAP constructs lacking GAP activity or knockdown of endogenous FilGAP by small interference RNA (siRNA) induce spontaneous lamellae formation and stimulate cell spreading on fibronectin. Knockdown of endogenous FilGAP abrogates ROCK-dependent suppression of lamellae. Conversely, forced expression of FilGAP induces numerous blebs around the cell periphery and a ROCK-specific inhibitor suppresses bleb formation. ROCK phosphorylates FilGAP, and this phosphorylation stimulates its RacGAP activity and is a requirement for FilGAP-mediated bleb formation. FilGAP is, therefore, a mediator of the well-established antagonism of Rac by RhoA that suppresses leading edge protrusion and promotes cell retraction to achieve cellular polarity.
authors.affiliation: Hematology Division, Brigham and Women's Hospital, Department of Medicine, Harvard Medical School, Boston, MA 02115, USA. yohta@rics.bwh.harvard.edu
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Ohta
authors.forename: John H
authors.initials: JH
authors.lastname: Hartwig
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Stossel
mesh_terms: D016475:3T3 Cells; D000199:Actins / Q000378:metabolism*; D000577:Amides / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D003285:Contractile Proteins / Q000235:genetics / Q000378:metabolism*; D064448:Filamins; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D034622:RNA Interference; D018411:Spodoptera; D014162:Transfection; D020744:rac GTP-Binding Proteins / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000502:physiology*; D054460:rho-Associated Kinases
chemical_list: C497033:ARHGAP24 protein, human; D000199:Actins; D000577:Amides; D003285:Contractile Proteins; D064448:Filamins; D020690:GTPase-Activating Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008840:Microfilament Proteins; D011725:Pyridines; C108830:Y 27632; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D020744:rac GTP-Binding Proteins; D020741:rho GTP-Binding Proteins