title: P-Rex1 is a primary Rac2 guanine nucleotide exchange factor in mouse neutrophils.
abstract: Leukocyte chemoattractants regulate many leukocyte functions, including leukocyte chemotaxis, via the Rho family of small GTPases that include RhoA, Cdc42, and Rac. Previous work has revealed mechanisms by which chemoattractants regulate RhoA and Cdc42 in mouse neutrophils, but the mechanisms for regulation of Rac remain unclear even though Rac is important for neutrophil functions. Here, we characterized P-Rex1, a Gbetagamma and PIP(3)-regulated guanine nucleotide exchange factor that was initially identified as a Rac activator in response to chemoattractants, for its roles in the regulation of Rac activity and neutrophil functions. We generated a mouse line in which the P-Rex1 gene is disrupted and found that P-Rex1 deficiency did not significantly affect Rac1 activation but diminished Rac2 activation in response to a chemoattractant fMLP in mouse neutrophils. This preference for Rac2 may partially result from the apparent higher affinity of P-Rex1 for Rac2 than for Rac1 because P-Rex1 was more readily immunoprecipitated with Rac2(S17N) than Rac1(S17N). In addition, P-Rex1 deficiency significantly attenuated fMLP-induced F actin formation and superoxide production without affecting LPS- or PMA-induced production. Furthermore, P-Rex1 deficiency caused a chemotactic defect that is primarily attributed to a reduction in the migration rate rather than directionality.
authors.affiliation: Department of Genetics and Developmental Biology, University of Connecticut Health Center, Farmington, Connecticut 06410, USA.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Dong
authors.forename: Zhicheng
authors.initials: Z
authors.lastname: Mo
authors.forename: Gary
authors.initials: G
authors.lastname: Bokoch
authors.forename: Caiying
authors.initials: C
authors.lastname: Guo
authors.forename: Zhong
authors.initials: Z
authors.lastname: Li
authors.forename: Dianqing
authors.initials: D
authors.lastname: Wu
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D002364:Caseins; D002460:Cell Line; D002633:Chemotaxis / Q000502:physiology*; D003001:Cloning, Molecular; D004789:Enzyme Activation / Q000502:physiology; D018390:Gene Targeting; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation; D051379:Mice; D018345:Mice, Knockout; D009240:N-Formylmethionine Leucyl-Phenylalanine; D009479:Neuropeptides / Q000378:metabolism; D009504:Neutrophils / Q000378:metabolism* / Q000502:physiology*; D021381:Protein Transport / Q000502:physiology; D013481:Superoxides / Q000378:metabolism; D020744:rac GTP-Binding Proteins / Q000378:metabolism; D020830:rac1 GTP-Binding Protein; D000097766:RAC2 GTP-Binding Protein
chemical_list: D000199:Actins; D002364:Caseins; D020662:Guanine Nucleotide Exchange Factors; D009240:N-Formylmethionine Leucyl-Phenylalanine; D009479:Neuropeptides; D013481:Superoxides; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein; D000097766:RAC2 GTP-Binding Protein; C511197:PREX1 protein, mouse; C484602:Rac1 protein, mouse