Cellular functions of TC10, a Rho family GTPase: regulation of morphology, signal transduction and cell growth.
The small Ras-related GTPase, TC10, has been classified on the basis of sequence homology to be a member of the Rho family. This family, which includes the Rho, Rac and CDC42 subfamilies, has been shown to regulate a variety of apparently diverse cellular processes such as actin cytoskeletal organization, mitogen-activated protein kinase (MAPK) cascades, cell cycle progression and transformation. In order to begin a study of TC10 biological function, we expressed wild type and various mutant forms of this protein in mammalian cells and investigated both the intracellular localization of the expressed proteins and their abilities to stimulate known Rho family-associated processes. Wild type TC10 was located predominantly in the cell membrane (apparently in the same regions as actin filaments), GTPase defective (75L) and GTP-binding defective (31N) mutants were located predominantly in cytoplasmic perinuclear regions, and a deletion mutant lacking the carboxyl terminal residues required for post-translational prenylation was located predominantly in the nucleus. The GTPase defective (constitutively active) TC10 mutant: (1) stimulated the formation of long filopodia; (2) activated c-Jun amino terminal kinase (JNK); (3) activated serum response factor (SRF)-dependent transcription; (4) activated NF-kappaB-dependent transcription; and (5) synergized with an activated Raf-kinase (Raf-CAAX) to transform NIH3T3 cells. In addition, wild type TC10 function is required for full H-Ras transforming potential. We demonstrate that an intact effector domain and carboxyl terminal prenylation signal are required for proper TC10 function and that TC10 signals to at least two separable downstream target pathways. In addition, TC10 interacted with the actin-binding and filament-forming protein, profilin, in both a two-hybrid cDNA library screen, and an in vitro binding assay. Taken together, these data support a classification of TC10 as a member of the Rho family, and in particular, suggest that TC10 functions to regulate cellular signaling to the actin cytoskeleton and processes associated with cell growth.
Murphy
G A
GA
Department of Biochemistry, New York University Medical Center, New York 10016, USA.
Solski
P A
PA
Jillian
S A
SA
Pérez de la Ossa
P
P
D'Eustachio
P
P
Der
C J
CJ
Rush
M G
MG
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000737:chemistry; D002455:Cell Division; D048429:Cell Size; D002471:Cell Transformation, Neoplastic; D002522:Chlorocebus aethiops; D003285:Contractile Proteins; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation; D020558:GTP Phosphohydrolases / Q000145:classification / Q000172:deficiency / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D019204:GTP-Binding Proteins / Q000737:chemistry; D048031:JNK Mitogen-Activated Protein Kinases; D051379:Mice; D008840:Microfilament Proteins / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases; D008969:Molecular Sequence Data; D005810:Multigene Family; D016328:NF-kappa B / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D051304:Profilins; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000502:physiology; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D026362:Serum Response Factor; D015398:Signal Transduction / Q000502:physiology*; D014158:Transcription, Genetic; D020764:cdc42 GTP-Binding Protein; D020744:rac GTP-Binding Proteins; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein
D018797:Cell Cycle Proteins; D003285:Contractile Proteins; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D008840:Microfilament Proteins; D016328:NF-kappa B; D009687:Nuclear Proteins; C495739:Pfn1 protein, mouse; D051304:Profilins; D011993:Recombinant Fusion Proteins; D026362:Serum Response Factor; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; C503260:Rhoq protein, mouse; D020764:cdc42 GTP-Binding Protein; D020744:rac GTP-Binding Proteins; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein