title: Phosphorylation of RhoGDI1 by p21-activated kinase 2 mediates basic fibroblast growth factor-stimulated neurite outgrowth in PC12 cells.
abstract: We previously showed that p21-activated kinase 2 (PAK2), a major PAK isoform expressed in PC12 cells, mediates neurite outgrowth via Rac1 GTPase. RhoGDI1 forms a complex with Rac1, resulting in its inhibition. Rac1 activation requires dissociation from RhoGDI1. Here, we show that PAK2 mediates basic fibroblast growth factor (bFGF)-stimulated neurite outgrowth via phosphorylation of RhoGDI1. RhoGDI1 was shown to be associated with PAK2, with phosphorylation of Ser34 and Ser101 by active PAK2 evident in vitro and in vivo. A RhoGDI1 phosphomimetic mutant (S34E/S101E) was dissociated from Rac1/Cdc42, whereas the wild-type or a nonphosphorylatable mutant (S34A/S101A) formed a tight complex. Consistent with this, PC12 cells expressing the phosphomimetic mutant displayed Rac1/Cdc42 activation in response to bFGF stimulation. Neurite outgrowth was also enhanced in PC12 cells expressing the phosphomimetic mutant. These results suggest that PAK2-mediated RhoGDI1 phosphorylation stimulates dissociation of RhoGDI1-Rac1/Cdc42 complex accompanied by relief of inhibitory effect on Rac1/Cdc42, which promotes neuronal differentiation.
authors.affiliation: Department of Biochemistry and Signaling Disorder Research Center, College of Medicine, Chungbuk National University, 410 Sungbong-ro, Gaesin-dong, Heungduk-ku, Cheongju 361-763, Republic of Korea.
authors.forename: Eun-Young
authors.initials: EY
authors.lastname: Shin
authors.forename: Eun-Sook
authors.initials: ES
authors.lastname: Shim
authors.forename: Chan-Soo
authors.initials: CS
authors.lastname: Lee
authors.forename: Hyong Kyu
authors.initials: HK
authors.lastname: Kim
authors.forename: Eung-Gook
authors.initials: EG
authors.lastname: Kim
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D005346:Fibroblast Growth Factors / Q000494:pharmacology; D020730:Guanine Nucleotide Dissociation Inhibitors / Q000235:genetics / Q000378:metabolism*; D016501:Neurites / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D009474:Neurons / Q000166:cytology* / Q000378:metabolism / Q000502:physiology; D016716:PC12 Cells; D010766:Phosphorylation; D051381:Rats; D012694:Serine / Q000235:genetics / Q000378:metabolism; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D054462:p21-Activated Kinases / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors
chemical_list: D020730:Guanine Nucleotide Dissociation Inhibitors; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors; D012694:Serine; D005346:Fibroblast Growth Factors; D054462:p21-Activated Kinases; C499134:Rac1 protein, rat; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein