C57BL/6-Tg(JAK2*)N1Rsko/J

Stock number: 037560
Product name: JAK2-N1; JAK2-N542-E543del

Research areas: Cancer Research, Cardiovascular Research, Cell Biology Research, Hematological Research, Immunology, Inflammation and Autoimmunity Research, Research Tools

Description

JAK2-N542-E543del transgenic mice conditionally express the human JAK2 (Janus kinase 2) gene carrying a deletion of codons 542 and 543 (AATGAA) in exon 12. Breeding JAK2-N542-E543del mice to a strain carrying Cre recombinase flips the orientation of the JAK2 cDNA and allows expression of the mutant transgene in offspring. This strain may be useful for studying the myeloproliferative neoplasm (MPN) polycythemia vera (PV).

Of note, mice carrying the JAK2 V617F mutation are available as Stock No. 037558).

Detailed description

JAK2 is a protein tyrosine kinase involved in a specific subset of cytokine receptor signaling pathways and is misregulated or mutated in some myeloproliferative diseases and cancers. When activated, JAK2 phosphorylates STAT transcription factors and initiates the JAK-STAT signaling pathway. Although a majority of polycythemia vera (PV) patients carry the V617F mutation, PV patients who are negative for V617F often carry a mutation in JAK2 exon 12 in the vicinity of the codon 539. Exon 12 mutations can result in higher hemoglobin values and lower platelet and leukocyte counts, but have the same incidences of thrombosis, myelofibrosis, and leukemia as patients with the V617F mutation.

JAK2-N542-E543del transgenic mice conditionally express the human JAK2 (Janus kinase 2) gene carrying the pathological deletion of codons 542 and 543 (AATGAA). JAK2 exon 12 sequence is placed in reverse orientation and is surrounded by lox71 and lox66 sites, allowing for cre-mediated inversion of the JAK2 cDNA, which restores the transgene to a functionally active configuration. Recombination is unidirectional and irreversible leaving one loxP site and a double lox66/71 site with a reduced affinity for cre. Mice homozygous for the unrecombined transgene are viable and fertile.

When JAK2-N542-E543del transgenic mice are combined with mice carrying the interferon inducible Tg(Mx1-cre)1Cgn (Stock No. 003556) allele, pIpC induced offspring develop a polycythemia vera (PV)-like phenotype characterized by increased hemoglobin, slightly reduced platelets, splenomegaly and decreased survival.

 When combined with mice carrying the inducible early hematopoietic progenitor and endothelial cell-specific Tg(Tal1-cre/ERT)42-056Jrg allele, tamoxifen treated offspring exhibit a reduced survival, with all mice dying 10 weeks after induction. Alternatively, other Cre-expressing strains can be used to activate the transgene.

Of note, mice carrying the JAK2 V617F mutation are available as Stock No. 037558).

Development

The JAK2-N542-E543del transgenic construct contains exons 1-12 from a BAC carrying the human JAK2 gene modified to include the deletion of N542 and E543 (AATGAA) cloned from a PV patient, an antiparallel lox66 site and a lox71 site flanking exon 12, a partial cDNA encoding JAK2 exons 13-25, and a polyA signal. The segment between the lox sites was inverted by restriction enzyme digest, creating an inducible Flip-Flop transgene. In the flipped configuration, the full length JAK2 protein cannot be made. The donating investigator indicates that BAC clone does not include any other known genes. Following genotyping verification, the modified BAC was microinjected into the pronuclei of fertilized C57BL/6 oocytes. Founder line N1 with 2 copies of the transgene was bred to C57BL/6N mice and maintained on the C57BL/6N background. Upon arrival, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6NJ oocytes (Stock No. 005304).

In 2022, a 48 SNP (single nucleotide polymorphism) panel analysis, with 43 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 males sent to The Jackson Laboratory Repository. Two of the 5 markers that determine C57BL/6J from C57BL/6N were found to be segregating on chromosomes 6 and 15. These data suggest the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6N;C57BL/6J genetic background.

Allele

Symbol: Tg(JAK2*)N1Rsko
Name: transgene insertion N1, Radek C Skoda
MGI accession ID: MGI:7327623
Generation method: Transgenic
Attributes: Inserted expressed sequence; Humanized sequence
Marker symbol: Tg(JAK2*)N1Rsko
Marker name: transgene insertion N1, Radek C Skoda
Chromosome: UN
Strain of origin: C57BL/6
Molecular note: The transgenic construct contains exons 1-12 from a BAC carrying the human JAK2 gene modified to include the deletion of N542 and E543 (AATGAA) cloned from a polycythemia vera (PV) patient, an antiparallel lox66 site and a lox71 site flanking exon 12, a partial cDNA encoding JAK2 exons 13-25, and a polyA signal. The segment between the lox sites was inverted by restriction enzyme digest, creating an inducible Flip-Flop transgene. In the flipped configuration, the full length JAK2 protein cannot be made.