These targeted mutant mice incorporate a knockout of the VPAC2 receptor (Vipr2) which may be useful in studies of circadian rhythm and experimental autoimmune encephalomyelitis (EAE).
James Waschek, UCLA
The VPAC2 receptor (Vipr2, vasoactive intestinal peptide receptor 2) is essential for circadian function in the mouse suprachiasmatic nuclei. Deficiency also exacerbates experimental autoimmune encephalomyelitis (EAE).
These mice incorporate a targeted knockout of the Vipr2 gene. RT-PCR confirms ablation of the wildtype transcript. Although incorporated in the targeting construct, no lacZ expression is detected in heterozygous or homozygous mutants at any stage of development. VPAC2 receptors are detected in gastric mucosa of wildtype mice, but not in Vipr2 knockout animals. Homozygotes are viable, fertile, and show no overt morphological phenotype.
Homozygous knockout mice display characteristic circadian phenotypes, as determined by wheel-running behavior. Both knockout and wildtype mice entrain to a 12 hour white light:12 hour dim red light lighting schedule. The overall activity of the knockout mice is significantly less than that of wildtype mice. When the lighting cycle is advanced by 8 hours, homozygous knockout mice re-entrain after just 2.4+/- 0.5 days (6.7 +/-0.5 days for wildtype).
In a model of MOG35-55-induced EAE, mice exhibit exacerbated clinical, histopathological and immunological features of the disease. Homozygous knockout mice have a more prolonged clinical disease course than wildtype animals (peaking at 18 days in mutant mice and 15 days in wildtype mice). Increases in Th1/Th17 responses and decreases in Th2/Treg responses are observed. RT-PCR of knockout mouse spinal cord reveals higher expression of pro-inflammatory cytokines Tnf, Il6, Ifn (Th1) and Il17a (Th17) but similar levels of Il23a (Th17-promoting) compared to wildtype mice 30 days post-EAE immunization. Levels of anti-inflammatory cytokines Il4 (Th2), Il10 (Th2/Treg), and Foxp3 (Treg marker) mRNA are reduced compared to wildtype.
Hapten-evoked cutaneous delayed-type hypersensitivity (DTH) is significantly enhanced in VPAC2 receptor knockout mice compared with age- and sex-matched wildtype mice. In contrast, generation of IgE anti-hapten antibodies and active cutaneous anaphylaxis is =70% lower in knockout mice than in wildtype animals.
A 132 bp segment of exon 1, incorporating the translation start site, was replaced with a cassette containing lacZ cDNA modified with a nuclear localization signal (nls) upstream of the neomycin resistance gene driven by the herpes simplex virus thymidine kinase promoter. The mutation was created via homologous recombination in E14/4 129P2/OlaHsd-derived embryonic stem cells. Resultant chimeric males were bred to C57BL/6J females. This strain was backcrossed to C57BL/6 (a mix of C57BL/6J and C57BL/6N) for more than seven generations.
|Allele Name||targeted mutation 1, Andrew J Harmar|
|Allele Type||Targeted (Null/Knockout)|
|Allele Synonym(s)||Vipr2-; VPAC2-; VPAC2R-null|
|Gene Symbol and Name||Vipr2, vasoactive intestinal peptide receptor 2|
|Strain of Origin||129P2/OlaHsd|
|General Note||ES cell line = E14/4.|
|Molecular Note||A vector containing nls-lacZ-PA-TK-neo replaced 132 bp of sequence in exon 1, which contains the translation start site. RT-PCR confirmed ablation of wild-type transcript and no lacZ expression was detected in mutants.|
Heterozygotes and homozygotes are viable and fertile.
When using the Vipr2- mouse strain in a publication, please cite the originating article(s) and include JAX stock #029215 in your Materials and Methods section.