These Rac2 knock-out mice exhibit vulnerability to invasive infection due to functional deficiencies in neutrophil and mast cell populations.
David A. Williams, Indiana University
Mice that are homozygous for the targeted mutation are viable, fertile, and normal in size but exhibit phagocytic immunodeficiency. No endogenous gene product (mRNA or protein) was detected by Northern blot analysis, RT-PCR or Western blot analysis. The Rac proteins are a subclass of the Rho family of GTPases, and are involved in actin cytoskeletal organization in cell movement, cell proliferation, kinase signaling pathways, and in superoxide production in phagocytic cells. Neutrophils and mast cells derived from homozygous mice display abnormal actin-based functions: cytoskeleton remodeling ability, adhesion, migration, degranulation, and phagocytosis. Diminished superoxide production in response to some agonists, and reduced total number of leukocytes and neutrophils in peritoneal exudate is observed. As result of functional deficiencies in neutrophil and mast cell populations, these mutant mice are more vulnerable to invasive infection. Slowed growth of mast cells, accompanying reduction in mast cell number and a significant decrease in growth factor-dependent survival was found to be due to increased cell apoptosis. These mutant mice may be useful in studies of phagocytic immunodeficiency, cellular inflammatory responses, hematopoietic cell regulation, and B cell development and signaling.
A targeting vector containing neomycin resistance and herpes simplex virus thymidine kinase genes was used to disrupt exon 1 of the Rac2 gene. The construct was electroporated into 129S6/SvEv derived CCE.1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6 blastocysts. The resulting chimeric animals were crossed to C57BL/6 mice.
|Allele Name||targeted mutation 1, Mary C Dinauer and David A Williams|
|Allele Type||Targeted (Null/Knockout)|
|Allele Synonym(s)||rac2-; Rac2tm1Daw|
|Gene Symbol and Name||Rac2, Rac family small GTPase 2|
|Strain of Origin||129S/SvEv-Gpi1c|
|Molecular Note||A neomycin resistance cassette replaced a genomic fragment containing exon 1, which encodes the translational initiation site and part of the GTP-binding domain. Northern blot and RT-PCR analysis demonstrated that no transcripts were detectable in total RNA derived from neutrophils or lymphocytes in homozygous mice. Western blot analysis confirmed an absence of protein produced from this allele in peritoneal exudate cells from homozygous mice.|
|Mutations Made By|| |
David Williams, Indiana University
This strain originated on a B6;129 background and has been backcrossed for at least 17 generations (11/01) on the C57BL/6 background. Homozygous mice must be maintained under specific pathogen-free conditions.
When using the Rac2 KO mouse strain in a publication, please cite the originating article(s) and include JAX stock #004197 in your Materials and Methods section.