title: Actions of Rho family small G proteins and p21-activated protein kinases on mitogen-activated protein kinase family members.
abstract: The mitogen-activated protein (MAP) kinases are a family of serine/threonine kinases that are regulated by distinct extracellular stimuli. The currently known members include extracellular signal-regulated protein kinase 1 (ERK1), ERK2, the c-Jun N-terminal kinase/stress-activated protein kinases (JNK/SAPKs), and p38 MAP kinases. We find that overexpression of the Ste20-related enzymes p21-activated kinase 1 (PAK1) and PAK2 in 293 cells is sufficient to activate JNK/SAPK and to a lesser extent p38 MAP kinase but not ERK2. Rat MAP/ERK kinase kinase 1 can stimulate the activity of each of these MAP kinases. Although neither activated Rac nor the PAKs stimulate ERK2 activity, overexpression of either dominant negative Rac2 or the N-terminal regulatory domain of PAK1 inhibits Ras-mediated activation of ERK2, suggesting a permissive role for Rac in the control of the ERK pathway. Furthermore, constitutively active Rac2, Cdc42hs, and RhoA synergize with an activated form of Raf to increase ERK2 activity. These findings reveal a previously unrecognized connection between Rho family small G proteins and the ERK pathway.
authors.affiliation: Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, 75235-9041, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Frost
authors.forename: S
authors.initials: S
authors.lastname: Xu
authors.forename: M R
authors.initials: MR
authors.lastname: Hutchison
authors.forename: S
authors.initials: S
authors.lastname: Marcus
authors.forename: M H
authors.initials: MH
authors.lastname: Cobb
mesh_terms: D000818:Animals; D001483:Base Sequence; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002460:Cell Line; D003001:Cloning, Molecular; D017077:Culture Media, Conditioned; D017931:DNA Primers; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D020930:MAP Kinase Kinase Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D013379:Substrate Specificity; D014162:Transfection; D054462:p21-Activated Kinases
chemical_list: D017077:Culture Media, Conditioned; D017931:DNA Primers; D047908:Intracellular Signaling Peptides and Proteins; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D011505:Protein-Tyrosine Kinases; C515903:PAK1 protein, human; C515906:Pak1 protein, rat; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; C078754:STE20 protein, S cerevisiae; D019204:GTP-Binding Proteins