These LMP-7 KO mice may be useful for studying the role of the immunoproteasomes in T cell proliferation.
Alice Sijts, University Utrecht
In this strain, a neo cassette replaces exons 1-5 of the proteasome (prosome, macropain) subunit, beta type 8 (Psmb8) gene, abolishing gene expression.
Psmb8 encodes low molecular mass polypeptide (LMP)-7, one of three catalytic immunosubunits that make up immunoproteasomes. In response to interferon-gamma (IFNγ) or tumor necrosis factor-alpha (TNF-α), cytokines that are released in the early stages of viral infections, catalytic immunosubunits are rapidly assembled to form immunoproteasomes. These specialized proteasomes are formed in most cells, including lymphoid cells, and have a relatively short life span of a few days. They process MHC class I Ag and play a role in CD8+ T cell proliferation. Homozygous mice are viable and fertile. These LMP-7-/- mice exhibit a reduced ability to process class I restricted antigens, leading to a 25-50% reduction of MHC class I cell surface antigens. These mice have a reduced number of functional T cells.
A targeting vector was designed to replace exons 1-5 of the proteasome (prosome, macropain) subunit, beta type 8 (Psmb8) gene with a neomycin resistance (neo) cassette. The construct was electroporated into 129P2/OlaHsd-derived E14.1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts and the resulting chimeric males were bred to C57BL/6 females.
Another targeting vector was designed to replace exons 5-7 of the proteasome (prosome, macropain) subunit, beta type 10 (Psmb10) gene with a neomycin resistance (neo) cassette. The construct was electroporated into 129S2/SvPas-derived D3 embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts and the resulting chimeric males were bred to C57BL/6 females to generate a colony of Psmb10tm1Mgro knockout mice.
Mice carrying the mutations were crossed, and the resulting double mutants were backcrossed for at least 10 generations to C57BL/6 mice. Upon arrival at The Jackson Laboratory, mice were bred to C57BL/6J (Stock No. 000664) for at least one generation to establish the colony. The Psmb10tm1Mgro allele was selected against, and was maintained as a separate strain (Stock No. 021607).
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. Three of 27 markers throughout the genome, as well as 2 of 5 markers that determine C57BL/6J from C57BL/6N, were found to be segregating. One marker on chromosome 11 was from an unknown source. This suggests a contamination from an unknown source or incomplete backcross.
|Allele Name||targeted mutation 1, H J Fehling|
|Allele Type||Targeted (Null/Knockout)|
|Allele Synonym(s)||beta5i-; LMP7-; LMP-7-|
|Gene Symbol and Name||Psmb8, proteasome (prosome, macropain) subunit, beta type 8 (large multifunctional peptidase 7)|
|Strain of Origin||129P2/OlaHsd|
|Molecular Note||Exons 1-5, encoding the first 247 amino acids of the protein, were replaced with a neomycin resistance gene.|
When maintaining the live Psmb8tm1Hjf colony, homozygous mice may be bred together.
When using the LMP-7- mouse strain in a publication, please cite the originating article(s) and include JAX stock #021201 in your Materials and Methods section.