STOCK Mecom^tm3.1Aspe/J

Stock number: 032862
Product name: Evi1-TO
Research areas: Research Tools

Description

Evi1-TO mice carry a tetracycline operon (tetO) knocked into the first exon of the mouse Mecom gene. When bred with mice expressing a tetracycline transactivator or reverse transactivator protein, expression of EVI1 isoforms of Mecom (associated with human 3q26-related myeloid leukeumias) can be controlled in the offspring by withdrawal or administration of a tetracycline analog.

Detailed description

Inv(3q26) is a genetic mutation associated with myeloid malignancies that have a poor prognosis. It results in marked overexpression of EVI1 transcripts of the MECOM (MDS1 and EVI1 complex locus) gene that encodes a zinc-finger transcription factor and myeloid-specific oncoprotein.

Evi1-TO mice carry a tetracycline operon (tetO) knocked into the first exon of the mouse Mecom gene. When bred with mice expressing a tetracycline transactivator or reverse transactivator protein, expression of EVI1 isoforms of Mecom (associated with human 3q26-related myeloid leukeumias) can be controlled in the offspring by withdrawal or administration of a tetracycline analog (doxycycline).

Progeny of these Evi1-TO mice crossed with Rosa26-rtTA animals (Gt(ROSA)26Sor^{tm1(rtTA*M2)Jae}; e.g. Stock No. 006965) that are induced with doxycycline show a dramatic upregulation of the major EVI1 transcript in hematopoietic cells to levels seen in leukemic cells. The longer MDS1-EVI1 mRNA transcript is not upregulated. This accurately models the pattern of MECOM expression commonly seen in human AML with 3q26 rearrangements. Chronic overexpression of EVI1 under doxycycline treatment can result in leukemia with mice becoming moribund at 90-119 days, as demonstrated by Evi1^TO/TO/Rosa26^rtTA/rtTA bone marrow cell transplant experiments.

This improved model of EVI1 overexpression in the hematopoietic system avoids the difficulties associated with previous bone marrow models in which transferred retrovirus is poorly tolerated and can induce quiescence.

Development

A loxP-FRT-neomycin-Stop-FRT-7x tetO-loxP (NSTO) cassette and minimal CMV promoter were introduced to exon 1 of the mouse Mecom gene via homologous recombination in embryonic stem (ES) cells. Resultant mice were crossed with B6.129S4-Gt(ROSA)26Sor^tm1(FLP1)Dym/RainJ mice (Stock No. 009086) expressing FlpE recombinase to excise the FRT-flanked neomycin-Stop component. Mice were backcrossed to C57BL/6 for more than 10 generations by the donating laboratory (see SNP note below).

In 2021, 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. Four of the 43 markers throughout the genome were segregating with 129, suggesting an incomplete backcross. Also, one of the 43 markers throughout the genome was segregating with an unknown source.

Allele

Symbol: Mecom^tm3.1Aspe
Name: targeted mutation 3.1, Archibald Perkins
MGI accession ID: MGI:6287968
Generation method: Targeted
Attributes: Inducible
Synonyms: Evi1^TO
Marker symbol: Mecom
Marker name: MDS1 and EVI1 complex locus
Marker synonyms: AML1-EVI-1; D630039M04Rik; EVI1; Evi-1; Jbo; KMT8E; Mds1; MDS1-EVI1; Prdm3; RUSAT2; ZNFPR1B1
Chromosome: 3
Strain of origin: Not Specified
Molecular note: The targeting construct introduced into exon 1 an FRT-flanked neomycin resistance cassette and STOP sequence followed by seven tet operons. Flp-mediated recombination removed the selection cassette and STOP sequence. The resulting allele is tetracycline-induced.