These CD70 knockout mice exhibit decreased numbers of antigen-specific CD8 T cells and impaired viral clearance after lymphocytic choriomeningitis virus infection. They may be useful in applications related to study of T cell proliferation/regulation and antiviral T cell responses by CD27-CD70 activation.
Jonathan D Ashwell, Nat Cancer Inst/Nat Inst Health NCI/NIH
CD70-/- mice lack exons 1-2 of the CD70 antigen (Cd70) gene, abolishing gene expression. Homozygous mice are viable and fertile. CD70 is constitutively expressed on thymic medullary cells and gut lamina propria dendritic cells (DC). It is also transiently expressed on DCs after activation via toll-like recpetors (TLRs) and engagement of CD40 with CD40L, and on activated T and B cells. CD70 levels are downregulated by interaction with its receptor CD27. CD27 is constitutively expressed by T cells as a membrane-bound homodimer, and its surface levels change during T cell activation. Surface levels of CD27 are downregulated during T cell effector differentiation by shedding and/or decreased transcription, and some terminally-differentiated effector memory T cells (TEM) retain a CD27-negative phenotype.
CD27-CD70 interactions play a role in T cell proliferation and antiviral T cell responses. These mice have decreased numbers of antigen-specific CD8 T cell and impaired viral clearance after lymphocytic choriomeningitis virus (LCMV) infection. CD4 T cell responses were not affected.
A targeting vector was designed to insert a loxP site upstream of exon 1 and a frt-flanked neomycin resistance (neo) cassette, followed by a second loxP site, downstream of exon 2 of the CD70 antigen (Cd70) gene. The construct was electroporated into 129 x C57BL/6 embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts and resulting chimeric mice were with B6.Cg-Tg(ACTFLPe)9205Dym/J transgenic mice (Stock No. 005703) to delete the neo cassette. Progeny were subsequently crossed with FVB/N-Tg(ACTB-cre)2Mrt/J transgenic mice (Stock No. 003376) to delete exons 1-2. Offspring were crossed to remove the Flp- and cre-expressing transgenes. The donating investigator reported that these mice were bred to C57BL/6J mice for at least 9 generations (see SNP note below). Upon arrival, mice were bred to C57BL/6J inbred mice (Stock No. 000664) for at least one generation to establish the colony.
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. 1 of the 27 markers throughout the genome was segregating, and all 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 C57BL/6N genetic background.
|Allele Name||targeted mutation 1.1, Jonathan D Ashwell|
|Allele Type||Targeted (Null/Knockout)|
|Gene Symbol and Name||Cd70, CD70 antigen|
|Strain of Origin||129 x C57BL/6|
|Molecular Note||A floxed neo cassette was inserted upstream of exon 1. The neo cassette was then excised in properly targeted cells by cre recombinase. A cassette composed of an FRT flanked neo and another loxP site was then inserted downstream of exon 2. This second neo cassette was then removed by crossing to mice carrying Tg(ACTFLPe)9205 Dym. Subsequently, mice were crossed to Tg(ACTB-cre)2Mrt mice to excise exons 1 and 2. Bone marrow derived dendritic cells stimulated with lipopolysaccharide fail to produce mutant mRNA and no protein is expressed on the surface of stimulated splenocytes.|
When maintaining a live colony, homozygous mice may be bred together.
When using the B6.Cg-Cd70tm1.1Jda/J mouse strain in a publication, please cite the originating article(s) and include JAX stock #023319 in your Materials and Methods section.