title: DLC1 activation requires lipid interaction through a polybasic region preceding the RhoGAP domain.
abstract: Deleted in Liver Cancer 1 (DLC1) is a GTPase-activating protein (GAP) with specificity for RhoA, RhoB, and RhoC that is frequently deleted in various tumor types. By inactivating these small GTPases, DLC1 controls actin cytoskeletal remodeling and biological processes such as cell migration and proliferation. Here we provide evidence that DLC1 binds to phosphatidylinositol-4,5-bisphosphate (PI(4,5)P(2)) through a previously unrecognized polybasic region (PBR) adjacent to its RhoGAP domain. Importantly, PI(4,5)P(2)-containing membranes are shown to stimulate DLC1 GAP activity in vitro. In living cells, a DLC1 mutant lacking an intact PBR inactivated Rho signaling less efficiently and was severely compromised in suppressing cell spreading, directed migration, and proliferation. We therefore propose that PI(4,5)P(2) is an important cofactor in DLC1 regulation in vivo and that the PBR is essential for the cellular functions of the protein.
authors.affiliation: Institute of Cell Biology and Immunology, University of Stuttgart, 70569 Stuttgart, Germany.
authors.forename: Patrik
authors.initials: P
authors.lastname: Erlmann
authors.forename: Simone
authors.initials: S
authors.lastname: Schmid
authors.forename: Florian A
authors.initials: FA
authors.lastname: Horenkamp
authors.forename: Matthias
authors.initials: M
authors.lastname: Geyer
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Pomorski
authors.forename: Monilola A
authors.initials: MA
authors.lastname: Olayioye
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D002460:Cell Line; D017124:Conserved Sequence; D004797:Enzyme-Linked Immunosorbent Assay; D020690:GTPase-Activating Proteins; D006160:Guanosine Triphosphate / Q000502:physiology; D006801:Humans; D008563:Membrane Lipids / Q000502:physiology*; D008969:Molecular Sequence Data; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000502:physiology*; D010743:Phospholipids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000502:physiology; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
chemical_list: D000596:Amino Acids; C112352:DLC1 protein, human; D020690:GTPase-Activating Proteins; D008563:Membrane Lipids; D019269:Phosphatidylinositol 4,5-Diphosphate; D010743:Phospholipids; D011993:Recombinant Fusion Proteins; D025521:Tumor Suppressor Proteins; D006160:Guanosine Triphosphate; D020742:rhoA GTP-Binding Protein