title: Rho family GTPases bind to phosphoinositide kinases.
abstract: Rho family GTPases appear to play an important role in the regulation of the actin cytoskeleton, but the mechanism of regulation is unknown. Since phosphoinositide 3-kinase and phosphatidylinositol 4,5-bisphosphate have also been implicated in actin reorganization, we investigated the possibility that Rho family members interact with phosphoinositide kinases. We found that both GTP- and GDP-bound Rac1 associate with phosphatidylinositol-4-phosphate 5-kinase in vitro and in vivo. Phosphoinositide 3-kinase also bound to Rac1 and Cdc42Hs, and these interactions were GTP-dependent. Stimulation of Swiss 3T3 cells with platelet-derived growth factor induced the association of PI 3-kinase with Rac in immunoprecipitates. PI 3-kinase activity was also detected in Cdc42 immunoprecipitates from COS7 cells. These results suggest that phosphoinositide kinases are involved in Rho family signal transduction pathways and raise the possibility that the effects of Rho family members on the actin cytoskeleton are mediated in part by phosphoinositide kinases.
authors.affiliation: Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: K F
authors.initials: KF
authors.lastname: Tolias
authors.forename: L C
authors.initials: LC
authors.lastname: Cantley
authors.forename: C L
authors.initials: CL
authors.lastname: Carpenter
mesh_terms: D019870:1-Phosphatidylinositol 4-Kinase; D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism; D002460:Cell Line; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D011233:Precipitin Tests; D011485:Protein Binding; D051381:Rats; D020764:cdc42 GTP-Binding Protein; D020744:rac GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein
chemical_list: D018797:Cell Cycle Proteins; D017853:Phosphotransferases (Alcohol Group Acceptor); D019870:1-Phosphatidylinositol 4-Kinase; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D020764:cdc42 GTP-Binding Protein; D020744:rac GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein