B6.129S2-Pax5^tm1Mbu/J

Stock number: 028198
Product name: Pax5^lacZ KO
Research areas: Developmental Biology Research, Immunology, Inflammation and Autoimmunity Research, Neurobiology Research, Research Tools

Description

This Pax5^lacZ knockout strain homozygous postnatal lethality, abnormal cerebellar morphology and arrested B cell differentiation. These mice may be suitable for use in studies related to B lymphopoiesis and CNS development.

Detailed description

The Pax5 gene encodes a transcription factor important during B cell development, as well as brain development and spermatogenesis. Mutations in the human PAX5 gene are associated with several lymphomas. These Pax5^lacZ mice carry an in-frame insertion of lacZ in exon 2, which disrupts gene expression and serves as a reporter. Homozygotes are postnatal lethal, dying at approximately 3 weeks of age. Mice that are heterozygous for the targeted mutation are viable and fertile. No gene product (mRNA) is detected by RNase protection assay of 12.5 day old embryos, spleen from 2 week old homozygous, and testes from 6 month old homozygous. Homozygotes, while indistinguishable from littermates at birth, exhibit growth delays by 2 weeks of age, weighing approximately 1/3 of the wildtype control weight. Homozygotes on the 129 background exhibit limb-clasping, reduced posterior midbrain regions, anterior expansion of the cerebellar culmen, and abnormal cerebellar foliation. Heterozygotes on the mixed B6;129S2 background, exhibit abnormal cerebellar morphology. On the mixed B6;129S2 background, homozygotes display arrested B cell development at the pro-B cell stage, with an increased number of mature T cells detected in the spleen. Homozygotes are are osteopenic, with increased number of osteoclasts. During backcrossing, the Y chromosome may not have been fixed to the C57BL/6J genetic background.

Development

A targeting vector containing neomycin resistance and lacZ genes was used to disrupt most of exon 2. The construct inserts nuclear localization signal (from simian virus 40 large T antigen) and lacZ in-frame at codon 21 in exon 2. The construct was electroporated into 129S2/SvPas derived D3 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6 blastocysts. The resulting chimeric animals were tested for germline transmission. The resulting chimeric animals were crossed to 129S2 mice, and then backcrossed to C57BL/6J for more than 10 generations. During backcrossing, the Y chromosome may not have been fixed to the C57BL/6J genetic background. Upon arrival, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes (Stock No. 000664).

Allele

Symbol: Pax5^tm1Mbu
Name: targeted mutation 1, Meinrad Busslinger
MGI accession ID: MGI:1926938
Generation method: Targeted
Attributes: Reporter; Null/Knockout
Marker symbol: Pax5
Marker name: paired box 5
Chromosome: 4
Strain of origin: 129S2/SvPas
Expressed genes: lacZ,beta-galactosidase,E. coli
Site of expression: Posterior midbrain.
Molecular note: Disruption of the Pax5 gene by an in-frame fusion of the 5'genomic sequences of Pax5 (at codon 21 in exon 2) to a LacZ reporter gene containing a nuclear localization signal.