C57BL/6-Tg(Car1-cre)5Flt/J

Stock number: 016097
Research areas: Research Tools

Description

This CAC5 transgenic mouse strain expresses Cre recombinase under the control of the mouse Car1 promoter and may be useful in generating large intestine specific-targeted mutants for colon disease research. It has been determined that the transgene inserted on chr 8 (details below); there are no genes annotated in the region of the insertion.

Detailed description

These transgenic mice express Cre recombinase under the control of the mouse Car1, carbonic anhydrase 1, promoter. Transgenic transcript is detected in the tissues of the large intestine (cecum, proxmial and distal colon) by RT-PCR. Low levels of transcript are detected in the liver, and no transgene transcript is detected in kidney, stomach, bone marrow, prostate, lung, thymus, liver hear, duodenum, jejunum, ileum, pancreas, spleen. Mosaic recombinase activity is detected as early as 14.5 dpc in approximately 15% of the epithelial cells of the large intestine and is observed in individual crypts from the base to lumen. When crossed with a strain containing loxP site-flanked sequences, cre-mediated recombination results in large intestine epithelial-specific deletion of the flanked sequences in the offspring. Mice that are homozygous for the transgene are viable, normal in size and do not display any gross physical or behavioral abnormalities.

Development

A transgenic construct containing the cre, Cre recombinase, gene under the control of the mouse Car1, carbonic anhydrase 1, promoter was injected into fertilized C57BL/6J mouse eggs. The donating investigator reported that the resulting transgenic mice were crossed to C57BL/6J (see SNP note below). Founder line 5 was subsequently established. Upon arrival at The Jackson Laboratory, the mice were crossed to C57BL/6J (Stock No. 000664) at least once to establish the colony.

In 2022, the donating investigator reported that ~3-22 copies of the transgene have integrated on chromosome 8 (85,597,602-85,597,668 [GRCm38]) and resulted in a 64bp deletion of genomic region in between the two identified breakpoints. There are no genes annotated in this region [NCBI genome browser - GRCm38 - Chr8:85,597,400-85,597,800].

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, 3 of 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 C57BL/6J ; C57BL/6N genetic background.

Allele

Symbol: Tg(Car1-cre)5Flt
Name: transgene insertion 5, James C Fleet
MGI accession ID: MGI:4835007
Generation method: Transgenic
Attributes: Recombinase-expressing
Marker symbol: Tg(Car1-cre)5Flt
Marker name: transgene insertion 5, James C Fleet
Chromosome: 8
Strain of origin: C57BL/6J
Expressed genes: cre,cre recombinase,bacteriophage P1
Site of expression: mice express Cre recombinase in the tissues of the large intestine (cecum, proxmial and distal colon).
Molecular note: The 10.6 kb colon-specific promoter and the share 2.5 kb erythroid/colon enhancer from the mouse Car1 gene were PCR amplified and cloned in front of the cre recombinase gene in a plasmid vector. The purified construct was used to generated transgenic mice. Two lines were selected for further analysis. Line 5 (CAC5 with 40 copies to the transgene insertion) was shown by PCR to have 10-fold higher transgene mRNA levels than line 6 (CAC6 having 20 copies). The mRNA was detectable only in the large intestine from cecum to distal colon. A low level of mRNA expression was detected in the liver, but no other tissues analyzed expressed the transgene. In 2022, the investigator reported that ~3-22 copies of the transgene are integrated on chromosome 8 (85,597,602-85,597,668 [GRCm38]) and resulted in a 64bp deletion of genomic region in between the two identified breakpoints. There are no genes annotated in this region [NCBI genome browser - GRCm38 - Chr8:85,597,400-85,597,800].