C57BL/6J-Gt(ROSA)26Sor^{tm2(EWSR1/KLF15)Cklr}/J

Stock number: 041179
Product name: EWSR1::KLF15 conditional
Research areas: Cancer Research, Mouse/Human Gene Homologs, Research Tools

Description

EWSR1::KLF15 mice express a EWSR1::KLF15 fusion protein after removal of a STOP sequence by Cre recombinase. These mice are useful when studying Myoepithelial Carcinoma (MEC) and when testing therapies including immunotherapies.

Detailed description

The EWSR1::KLF15 conditional allele was inserted into the Gt(ROSA)26Sor locus. The allele contains (from 5' to 3') a loxP site, a neo cassette, a lox2272 site, a human Ewing sarcoma breakpoint region 1 fusion (EWSR1) cDNA fused to a human Kruppel-like transcription factor 15 (KLF15) cDNA with a polyadenylation signal, and second loxP and lox2272 sites in opposite orientations to their companion lox sites. The floxed EWSR1::KLF15 fusion sequence is inserted in opposite orientation to the endogenous Gt(ROSA)26Sor gene. The floxed neo cassette in the allele blocks expression of the EWSR1::KLF15 fusion protein before Cre recombination. Forward and reverse loxP and lox2272 sites are configured such that Cre-mediated recombination flips the EWSR1::KLF15 cDNA into correct transcriptional orientation and the neo cassette is removed.

The EWSR1 gene is frequently rearranged by reciprocal chromosomal translocation to create chimeric oncogenes and cognate oncoproteins seen in Ewing sarcoma. Ewing sarcoma and non-Ewing sarcomas are part of a family of EWSR1-rearranged solid tumors, rare cancerous tumors that develop in bones and soft tissues including muscles, tendons, and ligaments. The EWSR1::KLF15 translocation is seen in Myoepithelial Carcinoma (MEC) which occurs mainly in salivary glands but can also occur in soft tissues or bone.

EWSR1::KLF15 mice are viable, are normal weight, and are born at Mendelian ratios before Cre recombination. Cancer will not develop in these mice until mated to a Cre-expressing strain, with or without a second mutation such as mutations in the transformation related protein 53 (Trp53) gene.

Development

The EWSR1::KLF15 conditional allele was inserted into the Gt(ROSA)26Sor locus. The allele contains (from 5' to 3') a loxP site, a neomycin resistance (neo) cassette, a lox2272 site, a human Ewing sarcoma breakpoint region 1 fusion (EWSR1) cDNA fused to a human Kruppel-like transcription factor 15 (KLF15) cDNA with a polyadenylation signal, and second loxP and lox2272 sites in opposite orientations to their companion lox sites. The EWSR1::KLF15 fusion sequence is inserted in opposite orientation to the endogenous Gt(ROSA)26Sor gene. The construct was electroporated into C57BL/6J-derived embryonic stem (ES) cells developed by Ozgene. Correctly targeted ES cells were injected into recipient embryos and chimeric males were bred to C57BL/6J female mice (Stock No. 000664). The resulting EWSR1::KLF15 colony was not backcrossed by the donating laboratory. Upon arrival at The Jackson Laboratory, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes.

Allele

Symbol: Gt(ROSA)26Sor^{tm2(EWSR1/KLF15)Cklr}
Name: targeted mutation 2, Charles Keller
MGI accession ID: MGI:8270517
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); Inserted expressed sequence
Marker symbol: Gt(ROSA)26Sor
Marker name: gene trap ROSA 26, Philippe Soriano
Marker synonyms: beta geo; Gtrgeo26; Gtrosa26; R26; ROSA26; SETD5-AS1; Thumpd3as1
Chromosome: 6
Strain of origin: C57BL/6J
Molecular note: The allele contains (from 5' to 3') a loxP site, a neomycin resistance (neo) cassette, a lox2272 site, a human Ewing sarcoma breakpoint region 1 fusion (EWSR1) cDNA fused to a human Kruppel-like transcription factor 15 (KLF15) cDNA with a polyadenylation signal, and second loxP and lox2272 sites in opposite orientations to their companion lox sites. The EWSR1::KLF15 fusion sequence is inserted in opposite orientation to the endogenous Gt(ROSA)26Sor gene.