Homozygotes of this Tet2 knockout strain exhibit increases in the numbers of bone marrow myeloid progenitor cells and hematopoietic stem cells. These mice would be suitable in applications related to DNA demethylation, hematopoietic stem cell self-renewal and differentiation, hematopoiesis and tumorigenesis.
Anjana Rao, La Jolla Institute for Allergy and Immunology
The tet methylcytosine dioxygenase 2 (Tet2) gene encodes a methylcytosine dioxygenase involved in myelopoiesis, tumor suppression and DNA demethylation. These mice carry a targeted mutation of the Tet2 gene in which exons 8 through 11 (encoding the catalytic domain) are deleted. No gene product (mRNA) is detected by real time PCR analysis of naive CD4 T cells from homozygotes. Homozygotes exhibit an increase in the total number of cells in the bone marrow and spleen. The numbers of bone marrow myeloid progenitor cells and hematopoietic stem cells are increased in homozygotes at 8 to 12 weeks of age. Knockout mice have reduced levels of 5-hydroxymethylcytosine in bone marrow and spleen. During backcrossing, the Y chromosome may not have been fixed to the C57BL/6J genetic background.
Mice that are homozygous for the allele are viable and fertile. The Donating Investigator reports that homozygous x homozygous crosses can produce fewer pups than homozygous female x heterozygous male crosses. The Jackson Laboratory also observes homozygous breeders of both sexes may die early, and have now changed to maintaining our live colony by breeding heterozygous mice with wildtype from the colony [November 2020].
A targeting vector designed containing FRT flanked NEO cassette with a 3' loxP site was utilized in the construction of this mutant. This selection cassette was inserted downstream of exon 10. A second loxP site was inserted upstream of exon 8. The construct was electroporated into C57BL/6NTac derived ART B6-3 embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts. The resulting chimeric animals were crossed to CMV-CRE deleter mice (on a B6 background) to excise exons 8 through 11. The donating investigator reported that these mice were then backcrossed to C57BL/6J for more than 10 generations (see SNP note below). During backcrossing, the Y chromosome may not have been fixed to the C57BL/6J genetic background. Upon arrival at The Jackson Laboratory, the mice were crossed to C57BL/6J (Stock No. 000664) at least once 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. While the 27 markers throughout the genome suggested a C57BL/6 genetic background, 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 mixed mixed C57BL/6J ; C57BL/6N genetic background.
|Allele Name||targeted mutation 1.2, Anjana Rao|
|Allele Type||Targeted (Null/Knockout)|
|Gene Symbol and Name||Tet2, tet methylcytosine dioxygenase 2|
|Strain of Origin||C57BL/6NTac|
|Molecular Note||A loxP site was inserted upstream of exon 8 and an FRT flanked neo cassette and second loxP site were inserted downstream of exon 10 via homologous recombination. Recombinase mediated recombination removed exons 8 - 10 and the neo cassette.|
The Donating Investigator reports that homozygous x homozygous crosses can produce fewer pups than homozygous female x heterozygous male crosses.
The Jackson Laboratory also observes homozygous breeders of both sexes may die early, and have now changed to maintaining our live colony by breeding heterozygous mice with wildtype from the colony [November 2020].
When using the Tet2- mouse strain in a publication, please cite the originating article(s) and include JAX stock #023359 in your Materials and Methods section.