B6.129S6-Mecom^tm1Aspe/Mmjax

Stock number: 036325
Product name: ME^m1, Mds1‐lacZ, Mds1‐m1
Research areas: Developmental Biology Research, Hematological Research, Internal/Organ Research, Research Tools

Description

ME^m1 lacZ knock-in/knock-out mice have a lacZ reporter inserted downstream of the transcriptional start site of the Mds1 isoform of the Mecom (MDS1 and EVI1 complex locus) gene resulting in a null allele of the Mds1 isoform. The Evi1 isoform is expressed at normal levels. Homozygous mice develop a severe and progressive kyphoscoliosis and a reduced number of hematopoietic stem cells. This strain may be useful for studying hematopoietic stem cell development and maintenance.

Detailed description

Mecom (MDS1 and EVI1 complex locus) encodes several transcription factor variants involved in hematopoiesis and implicated in leukemogenesis. The Evi1 (ecotropic viral integration site 1) isoform is an oncogene with its own transcriptional start site and is associated with myeloid neoplasms. Mds1 (ME or myelodysplastic syndrome 1), located upstream of Evi1, is the longer isoform and contains a PRDF1-RIZ (PR) domain. ME is expressed specifically in long-term and short-term hematopoietic stem cells (HSCs), and also in emerging HSCs in the dorsal aorta at day E10.5-E11.5 of mouse gestation.

ME^m1 lacZ knock-in/knock-out mice contain a lacZ reporter inserted such that the Mds1 isoform is not expressed. The Evi1 isoform is expressed at normal levels. LacZ is under transcriptional control of the Mds1 promoter and provides β-gal staining of gene expression, which, in the embryo, includes the hematopoietic stem cells (only in the dorsal aorta, not the fetal liver), mesonephros, limbs, and parts of the brain. Mice heterozygous for ME^m1 are viable and fertile. ME^m1 homozygotes exhibit decreased fecundity and longevity (survival to at least 10 months) due to kyphosis, but are still able to breed. Severe and progressive kyphoscoliosis is observed beginning at 3 weeks of age and is accompanied by vertebral synostosis and osteopenia. Bone marrow elements are present in normal numbers overall, but the number of hematopoietic stem cells is markedly diminished when assessed by flow cytometry. This strain may be useful for studying hematopoietic stem cell development and maintenance and as a unique and specific marker of HSC emergence in the endothelium-to-hematopoietic transition.

Development

The MDSKO targeting construct contains a lacZ (encoding beta-galactosidase) with a nuclear localization signal and a bGH polyA site, a PGK-neomycin selection cassette and a pGH polyA site inserted downstream of the first ATG in exon 1 of Mecom on chromosome 3. The insertion is positioned such that the splice donor for exon 1 is lost. The construct was electroporated into 129S6/SvEvTac-derived TC1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts. Chimeric males were crossed to C57BL/6J females. Mice from the colony were then backcrossed to C57BL/6J for 20 generations. Upon arrival, mice were bred to C57BL/6J for at least 1 generation to establish the colony.

Allele

Symbol: Mecom^tm1Aspe
Name: targeted mutation 1, Archibald Perkins
MGI accession ID: MGI:5301305
Generation method: Targeted
Attributes: Reporter; Null/Knockout
Synonyms: Mds1-Evi1^tm1ap; ME^m1
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: 129S6/SvEvTac
Molecular note: A lacZ/neo cassette was inserted downstream of the translation initiation site. RNA analysis of adult tissues showed that MDS1-EVI1 (ME) transcripts are undetectable in all tissues except for a very low level in kidney, whereas levels of Evi1 mRNAs are normal.