Distinct cellular effects and interactions of the Rho-family GTPase TC10.
BACKGROUND
Rho-family GTPases have central roles in cytoskeletal organization, proliferation, differentiation and apoptosis. Multiple factors possessing overlapping specificities for Rho GTPases have been identified. The Rho GTPases Cdc42 and Rac share many regulators and effectors, yet produce different phenotypes when expressed as gain-of-function mutants in cells. The Rho-family member TC10 has remained almost completely uncharacterized, so it was of interest to determine whether TC10 has unique cellular effects and interacts with the same targets as Cdc42 and Rac.


RESULTS
A gain-of-function TC10 mutant protein expressed in fibroblasts induced cell rounding, loss of stress fibers and formation of peripheral extensions. The extensions were longer than those induced by the analogous Cdc42 mutant protein. Cells expressing TC10 also possessed fewer membrane ruffles and stress fibers than those expressing Cdc42. TC10 mRNA was most highly expressed in heart and skeletal muscle. The GTPase activity of TC10 was lower than that of Cdc42, and TC10 possessed a lower affinity for, but greater responsiveness to, the p50Rho GTPase-activating protein (p50RhoGAP) than did Cdc42. TC10 stimulated Jun N-terminal kinase (JNK) and p21-activated kinase (PAK) activities and interacted with a set of effectors (alpha-, beta- and gammaPAK, MRCKalpha/beta, MLK2, N-WASP and MSE55) that overlaps with those for Cdc42 and Rac. TC10 did not interact with MLK3 or WASP, and interacted only weakly with ACK-1.


CONCLUSIONS
TC10 possesses distinct features, but exhibits a phenotype most closely related to that of Cdc42. It interacts with a similar subset of effectors to Cdc42 but not with MLK3, WASP or ACK-1. It is regulated differentially by p50RhoGAP.
Neudauer
C L
CL
Center for Cell Signaling University of Virginia Charlottesville, Virginia, 22908, USA.
Joberty
G
G
Tatsis
N
N
Macara
I G
IG
D016475:3T3 Cells; D000818:Animals; D019556:COS Cells; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D051379:Mice; D020928:Mitogen-Activated Protein Kinases; D016297:Mutagenesis, Site-Directed; D010802:Phylogeny; D017354:Point Mutation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection; D054462:p21-Activated Kinases; D020744:rac GTP-Binding Proteins; D020741:rho GTP-Binding Proteins
D020690:GTPase-Activating Proteins; D011506:Proteins; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D006160:Guanosine Triphosphate; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; C503256:RHOQ protein, human; C503260:Rhoq protein, mouse; D020744:rac GTP-Binding Proteins; D020741:rho GTP-Binding Proteins