title: Gene targeting of Cdc42 and Cdc42GAP affirms the critical involvement of Cdc42 in filopodia induction, directed migration, and proliferation in primary mouse embryonic fibroblasts.
abstract: Recent studies in Cdc42 knockout mouse embryonic stem (ES) cells and ES-derived fibroblastoid cell lines raise concern on a body of literature derived by dominant mutant expression approach in a variety of cell lines implicating mammalian Cdc42 as a key regulator of filopodia induction, directional migration and cell cycle progression. To resolve the physiological function of mammalian Cdc42, we have characterized the Cdc42(-/-) and Cdc42GAP(-/-) primary mouse embryonic fibroblasts (MEFs) produced by gene targeting as the Cdc42 loss- or gain-of-activity cell model. The Cdc42(-/-) cells were defective in filopodia formation stimulated by bradykinin and in dorsal membrane ruffling stimulated by PDGF, whereas the Cdc42GAP(-/-) cells displayed spontaneous filopodia. The Cdc42 loss- or gain-of-activity cells were defective in adhesion to fibronectin, wound-healing, polarity establishment, and migration toward a serum gradient. These defects were associated with deficiencies of PAK1, GSK3beta, myosin light chain, and FAK phosphorylation. Furthermore, Cdc42(-/-) cells were defective in G1/S-phase transition and survival, correlating with deficient NF-kappaB transcription and defective JNK, p70 S6K, and ERK1/2 activation. These results demonstrate a different requirement of Cdc42 activity in primary MEFs from ES or ES-derived clonal fibroblastoid cells and suggest that Cdc42 plays cell-type-specific signaling roles.
authors.affiliation: Division of Experimental Hematology, Children's Hospital Medical Center, Molecular Developmental Biology Graduate Program, University of Cincinnati, Cincinnati, OH 45229, USA.
authors.forename: Linda
authors.initials: L
authors.lastname: Yang
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: Yi
authors.initials: Y
authors.lastname: Zheng
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D002448:Cell Adhesion / Q000502:physiology; D002453:Cell Cycle / Q000502:physiology; D002465:Cell Movement / Q000502:physiology*; D049109:Cell Proliferation; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D004622:Embryo, Mammalian / Q000166:cytology*; D005091:Exons / Q000235:genetics; D005347:Fibroblasts / Q000166:cytology*; D005353:Fibronectins / Q000378:metabolism; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism*; D018390:Gene Targeting; D051379:Mice; D018345:Mice, Knockout; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D011554:Pseudopodia / Q000378:metabolism*; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D015398:Signal Transduction; D020764:cdc42 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
chemical_list: D000199:Actins; C505158:Arhgap1 protein, mouse; D005353:Fibronectins; D020690:GTPase-Activating Proteins; D016328:NF-kappa B; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D020929:Mitogen-Activated Protein Kinase Kinases; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein