This iNOS knock-out strain may be suitable for use in studies of inflammatory conditions including rheumatoid arthritis, inflammatory bowel disease, cardiac allograft rejection, hepatoxicity, myocardial ischemia-reperfusion and septic shock.
IMR Colony, The Jackson Laboratory
Mice homozygous for the Nos2tm1Lau targeted mutation resemble wildtype mice in appearance and histology. Homozygotes are viable and fertile. Unlike Nos1 and Nos3, Nos2 is synthesized de novo in response to a variety of inflammatory stimuli. Induction of Nos2 results in the production of large amounts of nitric oxide (NO) over prolonged periods of time. Excessive NO production has been shown to be beneficial through its antitumor and antimicrobial activities. It is also thought to cause tissue damage and contribute to pathology in a variety of inflammatory conditions including rheumatoid arthritis, inflammatory bowel disease, cardiac allograft rejection, hepatoxicity, myocardial ischemia-reperfusion and septic shock. NO has been demonstrated to play a role in the regulation of blood pressure and hemodynamics. These iNOS knock-out mice carry an allele in which a NEO cassette replaced exons 12 and 13, which includes sequence encoding the calmodulin-binding domain. No gene product (mRNA or protein) is detected by Northern or Western blot analysis of LPS/IFN-gamma challenged peritoneal macrophages. Nitric acid synthase activity was not detected in cultured peritoneal macrophages.
In an LPS-induced model of septic shock, Nos2tm1Lau homozygotes had virtually no serum NO response, but were susceptible to LPS-induced death. Nos2tm1Lau homozygotes exhibit altered responses to M. bovis (BCG), systemic E. coli infection, M. tuberculosis and M.pulmonis. In addition, wound healing properties of fibroblasts are impaired in Nos2tm1Lau homozygotes. Also known as iNOS.
In an attempt to offer alleles on well-characterized or multiple genetic backgrounds, alleles are frequently moved to a genetic background different from that on which an allele was first characterized. This is the case for the strain above. It should be noted that the phenotype could vary from that originally described. We will modify the strain description if necessary as published results become available.
A targeting vector containing neomycin resistance and herpes simplex virus thymidine kinase genes was used to disrupt exons 12 and 13, encoding the calmodulin binding domain. The construct was electroporated into 129P2/OlaHsd derived E14TG2a embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6J blastocysts. The resulting chimeric animals were crossed to C57BL/6 mice, and then backcrossed to C57BL/6J for 11 generations (see SNP note below). The B6.129P2-Nos2 tm1Lau/J (Stock No. 002609) mice were then backcrossed to BALB/cByJ (Stock No. 001026) using a speed congenic protocol to produce this strain.
A 32 SNP (single nucleotide polymorphism) panel analysis, with 27 markers covering all 19 chromosomes and the X chromosome, as well as 5 markers that distinguish between the C57BL/6J and C57BL/6N substrains, was performed on the rederived living colony at The Jackson Laboratory Repository. While the 27 markers throughout the genome suggested a C57BL/6 genetic background, 1 of 5 markers that determine C57BL/6J from C57BL/6N were found to be segregating. These data suggest the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6J ; C57BL/6N genetic background.
|Allele Name||targeted mutation 1, Victor E Laubach|
|Allele Type||Targeted (Null/Knockout)|
|Allele Synonym(s)||iNOS-; iNOS KO; iNOS-; NOS2-; NOS2tm/Lau; Nos2tm1Lau|
|Gene Symbol and Name||Nos2, nitric oxide synthase 2, inducible|
|Strain of Origin||129P2/OlaHsd|
|Molecular Note||A neomycin cassette replaced exons 12 and 13 of the gene, which encode the calmodulin-binding domain. Northern and Western blots of IFNg/LPS-stimulated peritoneal macrophages showed no detectable Nos2 mRNA or protein, respectively.|
|Mutations Made By|| |
Dr. Victor Laubach, University of Virginia Health Sci. Ctr.
When maintaining a live colony, these mice can be bred as homozygotes.
When using the iNOS- mouse strain in a publication, please cite the originating article(s) and include JAX stock #007072 in your Materials and Methods section.