MRL.Cg-B2m^tm1Unc Fas^lpr

Stock number: 002455
Research areas: Apoptosis Research, Cancer Research, Hematological Research, Immunology, Inflammation and Autoimmunity Research, Internal/Organ Research, Metabolism Research, Mouse/Human Gene Homologs, Research Tools

Description

These double mutant mice exhibit a substantial reduction in CD4^-CD8^- T cells and a diminution of autoimmune disease.

Detailed description

Mice homozygous for both the lymphoproliferation spontaneous mutation (Fas^lpr) and the B2m^tm1Unc targeted mutation are viable and fertile. Class I molecule-deficient B2m^tm1Unc mice were backcrossed to MRL/MpJ-Fas^lpr to study the role of MHC class I molecules in the development of systemic autoimmune disease. Double homozygous mutant mice demonstrated a substantial reduction in CD4^-CD8^- T cells and a diminution of autoimmune disease. Specifically, hypergammaglobulinemia; autoantibodies including anti-DNA, anti-Smith antigen, and rheumatoid factor; and glomerulonephritis were significantly reduced compared to MRL/MpJ-Fas^lpr homozygous mice. Moreover, the pattern of hypergammaglobulinemia suggests that the requirement for MHC class I proteins is restricted temporally to later stages of the disease.

Development

The B2m^tm1Unc mutant strain was developed in the laboratory of Dr. Beverly Koller and Dr. Oliver Smithies at the University of North Carolina at Chapel Hill. It was generated by a targeted disruption of the B2m gene. The 129-derived E14TG2a ES cell line was used. The MRL-Fas^lpr .129P2(B6)-B2m^tm1Unc strain was produced in the laboratory of Dr. Derry Roopenian at The Jackson Laboratory by backcrossing the B2m^tm1Unc mutation 10 times to MRL/MpJ-Fas^lpr inbred mice.

Allele

Symbol: B2m^tm1Unc
Name: targeted mutation 1, University of North Carolina
MGI accession ID: MGI:1857133
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: B2m
Marker name: beta-2 microglobulin
Chromosome: 2
Strain of origin: 129P2/OlaHsd
Molecular note: Insertion of a neomycin-resistance gene into the second exon.

Allele

Symbol: Fas^lpr
Name: lymphoproliferation
MGI accession ID: MGI:1856334
Generation method: Spontaneous
Attributes: Hypomorph
Marker symbol: Fas
Marker name: Fas (TNF receptor superfamily member 6)
Chromosome: 19
Strain of origin: MRL/Mp
Molecular note: Southern blotting experiments indicated that the mutation is a genomic rearrangement within the gene, probably within the second intron. Sequencing of genomic DNA and RT-PCR products from homozygous mutant mice revealed the insertion of an early transposable element (ETn) into intron 2. RT-PCR analysis of liver and thymus mRNA showed that the presence of the ETn leads to premature termination of transcription at the long terminal repeat (LTR) of the ETn and aberrant mRNA splicing. The mutation is "leaky," however, as full-length mRNA and a longer splice product incorporating a segment of the ETn as an extra intron are detected in the thymus at low levels.
General note: Fas^lpr, lymphoproliferation, recessive. This mutation was found during inbreeding of a strain MRL/Mp derived from crosses among strains LG, AKR, C3H, and C57BL/6. The resemblance has led to extensive use of Fas^lpr mice in attempts to determine the etiology of SLE and to evaluate therapies. However, the human APT1 gene (OMIM 134637) encodes the FAS antigen; Tnfrsf6 is not the homolog of the human (SLE) gene. The Cd72^c haplotype is a modifier of Fas^lpr-induced autoimmune disease. J:204782