Neutrophil functions and autoimmune arthritis in the absence of p190RhoGAP: generation and analysis of a novel null mutation in mice.
Beta(2) integrins of neutrophils play a critical role in innate immune defense, but they also participate in tissue destruction during autoimmune inflammation. p190RhoGAP (ArhGAP35), a regulator of Rho family small GTPases, is required for integrin signal transduction in fibroblasts. Prior studies have also suggested a role for p190RhoGAP in beta(2) integrin signaling in neutrophils. To directly test that possibility, we have generated a novel targeted mutation completely disrupting the p190RhoGAP-encoding gene in mice. p190RhoGAP deficiency led to perinatal lethality and defective neural development, precluding the analysis of neutrophil functions in adult p190RhoGAP(-/-) animals. This was overcome by transplantation of fetal liver cells from p190RhoGAP(-/-) fetuses into lethally irradiated wild-type recipients. Neutrophils from such p190RhoGAP(-/-) bone marrow chimeras developed normally and expressed normal levels of various cell surface receptors. Although p190RhoGAP(-/-) neutrophils showed moderate reduction of beta(2) integrin-mediated adherent activation, they showed mostly normal migration in beta(2) integrin-dependent in vitro and in vivo assays and normal beta(2) integrin-mediated killing of serum-opsonized Staphylococcus aureus and Escherichia coli. A neutrophil- and beta(2) integrin-dependent transgenic model of the effector phase of autoimmune arthritis also proceeded normally in p190RhoGAP(-/-) bone marrow chimeras. In contrast, all the above responses were completely blocked in CD18(-/-) neutrophils or CD18(-/-) bone marrow chimeras. These results suggest that p190RhoGAP likely does not play a major indispensable role in beta(2) integrin-mediated in vitro and in vivo neutrophil functions or the effector phase of experimental autoimmune arthritis.
Németh
Tamás
T
Department of Physiology, Semmelweis University School of Medicine, Budapest, Hungary.
Futosi
Krisztina
K
Hably
Csilla
C
Brouns
Madeleine R
MR
Jakob
Sascha M
SM
Kovács
Miklós
M
Kertész
Zsuzsanna
Z
Walzog
Barbara
B
Settleman
Jeffrey
J
Mócsai
Attila
A
D000818:Animals; D001169:Arthritis, Experimental / Q000201:enzymology* / Q000276:immunology* / Q000473:pathology; D001327:Autoimmune Diseases / Q000201:enzymology* / Q000276:immunology* / Q000473:pathology; D001854:Bone Marrow Cells / Q000276:immunology / Q000473:pathology; D018821:CD18 Antigens / Q000502:physiology; D002478:Cells, Cultured; D002999:Clone Cells; D004195:Disease Models, Animal; D020690:GTPase-Activating Proteins / Q000172:deficiency* / Q000235:genetics / Q000502:physiology; D020662:Guanine Nucleotide Exchange Factors / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009154:Mutation / Q000276:immunology*; D009504:Neutrophils / Q000201:enzymology / Q000276:immunology* / Q000473:pathology; D012097:Repressor Proteins / Q000172:deficiency* / Q000235:genetics / Q000502:physiology
C074560:ARHGAP35 protein, human; C513041:Arhgap35 protein, mouse; D018821:CD18 Antigens; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; D012097:Repressor Proteins