Rac2 Functions in Both Neutrophils and Macrophages To Mediate Motility and Host Defense in Larval Zebrafish.
Leukocyte motility is required for host defense responses. Rac-family Rho GTPases are implicated in leukocyte function; however, the distinct roles of different Rac isoforms in host defense in vivo have remained unclear. In this study, we generated Rac2-deficient zebrafish using transcription activator-like effector nucleases to directly compare the role of Rac2 in vivo in neutrophils and macrophages in motility and the response to infection. This zebrafish larval model is highly amenable to live imaging of leukocyte behavior, and we report that in rac2-/-larvae both neutrophils and macrophages are defective in basic motility, leading to impaired responses to localized wounds or infections. rac2-/-larvae are highly susceptible to infection with Pseudomonas aeruginosa, which can be almost fully rescued by ectopic expression of either Rac2 or Rac1 specifically in neutrophils, indicating that these isoforms have partially overlapping functions in vivo. Rescue of Rac2 expression specifically in macrophages also confers resistance to Pseudomonas infection, highlighting an important role for Rac2 in this leukocyte population as well. Surprisingly, in contrast to neutrophils expressing a Rac2 dominant inhibitory human disease mutation, rac2-/-neutrophils do not have altered polarity or mobilization from hematopoietic tissue, suggesting that a different Rac isoform, such as Rac1, also contributes to these phenotypes in vivo.
Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, WI 53706.
Emily E
EE
Rosowski
Department of Biological Sciences, Purdue University, West Lafayette, IN 47907.
Qing
0000-0002-9254-9951
Q
Deng
Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, WI 53706.|Department of Bacteriology, University of Wisconsin, Madison, WI 53706; and.
Nancy P
0000-0002-4386-9473
NP
Keller
Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, WI 53706; huttenlocher@wisc.edu.|Department of Pediatrics, University of Wisconsin, Madison, WI 53706.
Anna
A
Huttenlocher
D000818:Animals; D030801:Animals, Genetically Modified; D002454:Cell Differentiation; D002465:Cell Movement / Q000235:genetics; D016764:Cell Polarity; D002478:Cells, Cultured; D005393:Fish Diseases / Q000276:immunology*; D055786:Gene Knockout Techniques; D006801:Humans; D007113:Immunity, Innate; D007814:Larva; D008264:Macrophages / Q000276:immunology*; D009154:Mutation / Q000235:genetics; D009504:Neutrophils / Q000276:immunology*; D011552:Pseudomonas Infections / Q000235:genetics / Q000276:immunology*; D011550:Pseudomonas aeruginosa / Q000276:immunology*; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*; D020744:rac GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism; D000097766:RAC2 GTP-Binding Protein
D029961:Zebrafish Proteins; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein; D000097766:RAC2 GTP-Binding Protein; C000621813:Rac2 protein, zebrafish