title: The 70 kDa S6 kinase complexes with and is activated by the Rho family G proteins Cdc42 and Rac1.
abstract: The 70 kDa ribosomol S6 kinase (pp70S6k) plays an important role in the progression of cells through G1 phase of the cell cycle. However, little is known of the signaling molecules that mediate its activation. We demonstrate that Rho family G proteins regulate pp70S6k activity in vivo. Activated alleles of Cdc42 and Rac1, but not RhoA, stimulate pp70S6k activity in multiple cell types. Activation requires an intact effector domain and isoprenylation of Cdc42 and Rac1. Coexpression of Dbl, an exchange factor for Cdc42, also activates pp70S6k. Growth factor-induced activation of pp70S6k is abrogated by dominant negative alleles of Cdc42 and Rac1. In addition, Cdc42 and Rac1 form GTP-dependent complex with the catalytically inactive form of pp70S6k in vitro and in vivo, suggesting a mechanism by which these G proteins activate pp70S6k.
authors.affiliation: Harvard Medical School, Department of Cell Biology, Boston, Massachusetts 02115, USA.
authors.forename: M M
authors.initials: MM
authors.lastname: Chou
authors.forename: J
authors.initials: J
authors.lastname: Blenis
mesh_terms: D016475:3T3 Cells / Q000166:cytology / Q000201:enzymology; D000483:Alleles; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics; D001427:Bacterial Toxins; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000502:physiology; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004815:Epidermal Growth Factor / Q000037:antagonists & inhibitors; D029968:Escherichia coli Proteins; D020558:GTP Phosphohydrolases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D015870:Gene Expression / Q000502:physiology; D006133:Growth Substances / Q000502:physiology; D020662:Guanine Nucleotide Exchange Factors; D006150:Guanine Nucleotides / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D007536:Isomerism; D048031:JNK Mitogen-Activated Protein Kinases; D008565:Membrane Proteins; D051379:Mice; D020928:Mitogen-Activated Protein Kinases; D009154:Mutation / Q000502:physiology; D019869:Phosphatidylinositol 3-Kinases; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000502:physiology; D010940:Plant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000037:antagonists & inhibitors; D011090:Polyenes / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D015682:Retroviridae Proteins, Oncogenic / Q000235:genetics; D019893:Ribosomal Protein S6 Kinases; D015398:Signal Transduction / Q000502:physiology; D020123:Sirolimus; D000077191:Wortmannin; D020846:cdc42 GTP-Binding Protein, Saccharomyces cerevisiae; D048051:p38 Mitogen-Activated Protein Kinases; D020744:rac GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein
chemical_list: D000730:Androstadienes; D000935:Antifungal Agents; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D018797:Cell Cycle Proteins; D004815:Epidermal Growth Factor; D029968:Escherichia coli Proteins; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D006133:Growth Substances; D020662:Guanine Nucleotide Exchange Factors; D006150:Guanine Nucleotides; D006160:Guanosine Triphosphate; D048031:JNK Mitogen-Activated Protein Kinases; D008565:Membrane Proteins; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D010940:Plant Proteins; D010982:Platelet-Derived Growth Factor; D011090:Polyenes; D017346:Protein Serine-Threonine Kinases; D015682:Retroviridae Proteins, Oncogenic; D019893:Ribosomal Protein S6 Kinases; D020123:Sirolimus; D000077191:Wortmannin; D020846:cdc42 GTP-Binding Protein, Saccharomyces cerevisiae; D048051:p38 Mitogen-Activated Protein Kinases; D020744:rac GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein; C512843:Mcf2 protein, mouse; C071524:HokC protein, E coli