B6.Cg-Tg(Myh11-cre,-EGFP)2Mik/J

Stock number: 007742
Product name: smMHC^Cre/eGFP
Research areas: Cardiovascular Research, Developmental Biology Research, Research Tools

Description

These smMHC(Myh11)/Cre/eGFP transgenic mice may be useful in studies utilizing "Cre-lox" technology or fluorescent protein expression in smooth muscle, especially separation of vascular myocytes from the surrounding cellular environment to isolate muscle specific adaptations or disease responses.

Detailed description

Mice hemizygous for the smMHC/Cre/eGFP transgene (smMHC^Cre/eGFP) are viable and fertile, with the smooth muscle myosin heavy chain (smMHC or Myh11) promoter directing bicistronic Cre and EGFP protein expression to smooth muscle cells during development as well as in the adult mouse. Hemizygotes from founder line SMCG2 (SM2^Cre/GFP) display intense EGFP fluorescence restricted to vascular and nonvascular smooth muscle, with strong concordance between cre expression and EGFP fluorescence (verifying the use of fluorescence as a marker for conditional gene recombination). When bred with mice containing a loxP-flanked sequence of interest, the resulting offspring can have Cre-mediated recombination of the flanked sequence in smooth muscle. Homozygotes are viable and fertile, with smaller litter sizes and a higher incidence of perinatal mortality. These smMHC/Cre/eGFP transgenic mice may be useful in studies utilizing "Cre-lox" technology or fluorescent protein expression in smooth muscle, especially separation of vascular myocytes from the surrounding cellular environment to isolate muscle specific adaptations or disease responses.

Considerations for experimental use: The donating investigator reports that the transgene is expressed in female germ cells and that Cre protein (or maternal RNA) may be passed to all embryos. If bred to males carrying a "floxed" allele, all offspring (cre-positive or cre-negative) may exhibit universal Cre-mediated recombination of the allele during early embryonic development. The donating investigator also reports transgene expression in the male germ line; post meiotic spermatagonia transiently express Cre recombinase with expression ending prior to fertilization. Therefore, Cre activity may be observed in all haploid male germ cells (cre-positive or cre-negative). If transgenic males also harbor "floxed" alleles in their genome, these loci may undergo universal Cre-mediated recombination in the sperm. As Cre activity ceases before fertilization, the resulting offspring exhibit no universal deletion affect on any "floxed" allele(s) of maternal origin. Because smMHC/Cre/eGFP transgene expression is observed in both maternal and paternal germlines, it is recommended to maintain the smMHC/Cre/EGFP transgenic colony without additional "floxed" mutations in their genome.

Development

The smMHC/Cre/eGFP transgene was designed placing a Cre recombinase gene, internal ribosomal entry site (IRES), and an enhanced green fluorescent protein (EGFP) gene all downstream of the 16 kb mouse smooth muscle myosin heavy chain (smMHC or Myh11) promoter fragment. This transgene was microinjected into the pronucleus of B6D2F2 fertilized mouse eggs. Transgenic mice were bred to C57BL/6J, and the resulting transgenic offspring with a single integration site and highest copy number (founder line SMCG2) were established. These smMHC/Cre/eGFP mice were backcrossed to C57BL/6J inbred mice for at least 12 generations prior to arrival at The Jackson Laboratory. During the backcross, the Y chromosome may not have been fixed to the C57BL/6J genetic background.

Allele

Symbol: Tg(Myh11-cre,-EGFP)2Mik
Name: transgene insertion 2, Michael I Kotlikoff
MGI accession ID: MGI:2653286
Generation method: Transgenic
Attributes: Recombinase-expressing; Reporter
Marker symbol: Tg(Myh11-cre,-EGFP)2Mik
Marker name: transgene insertion 2, Michael I Kotlikoff
Chromosome: UN
Strain of origin: (C57BL/6 x DBA/2)F2
Expressed genes: cre,cre recombinase,bacteriophage P1; GFP,Green Fluorescent Protein,
Site of expression: EGFP and Cre recombinase are expressed in vascular and nonvascular smooth muscle during development and in the adult mouse.
Molecular note: The transgene consists of a mouse Myh11 promoter, a cre recombinase gene, an internal ribosome entry site (IRES) and an enhanced GFP gene. 16 kb of mouse Myh11 promoter sequences was used to drive the bicistronic transgene expression in smooth muscle cells. The promoter has also been reported to be active in female germ cells. A low frequency of deletion events are also observed by inheritance from the male germline.
General note: Two transgenic founders, SMCG2 and SMCG3, were created. Transgenic founders were bred to C57BL/6 mice.