C57BL/6J-Myh11^{em2(cre/ERT2)Jifz}/J

Stock number: 038824
Product name: Myh11-CreER^T2-P2A
Research areas: Research Tools

Description

Myh11-CreER^T2-P2A knock-in mice carry an inducible Cre recombinase-ERT2 fusion protein inserted into the Myh11 (myosin, heavy polypeptide 11, smooth muscle) locus. Mice have inducible cre expression in smooth muscle cells with minimal impact on endogenous Myh11 expression. This strain may be useful for research involving smooth muscle cells and smooth muscle cell-dependent cardiovascular diseases.

Of note, the constitutive Myh11-CreNLS^PA is distributed as B6.Cg-Myh11^{em1(icre)Jifz}/J (Stock No. 038823).

Detailed description

Myh11 (myosin, heavy polypeptide 11, smooth muscle) encodes a protein that is part of the myosin protein complex found in smooth muscles. Smooth muscles contract and relax involuntarilyy in the lining internal organs such as blood vessels, stomach and intestines.

Myh11-CreER^T2-P2A knock-in mice carry an inducible Cre recombinase-ERT2 fusion protein and followed by a P2A peptide inserted after the ATG of the Myh11 (myosin, heavy polypeptide 11, smooth muscle) locus. The mutation has a minimal impact on endogenous Myh11 mRNA and protein levels. Expression of Myh11 and systolic blood pressure are similar between wild-type and heterozygous mice Mice heterozygous for the mutation are viable and fertile; homozygous fertility has not been tested. When heterozygous mice are combined with cre-inducible fluorescent reporter lines (for example, B6.129(Cg)-Gt(ROSA)26Sor^{tm4(ACTB-tdTomato,-EGFP)Luo}/J, Stock No. 006148) tamoxifen-treated cre-positive progeny exhibit EGFP fluorescence (and decreased in TdTomato fluorescence) in aorta, bladder and jejunum. Cre recombinase activity is absent in cardiomyocytes and skeletal muscles. In comparison to transgenic Myh11-cre/ERT2 strains, this strain expresses high cre activity from the endogenous Myh11 promoter and is not located on the Y chromosome. The donating investigator indicates there is mild tamoxifen-independent cre activity in the aorta, bladder and GI tract. This strain may provide an improved model for smooth muscle cell targeted gene deletion.

Of note, the constitutive Myh11-CreNLS^P2A is distributed as B6.Cg-Myh11^{em1(icre)Jifz}/J (Stock No. 038823).

The Cre-ERT2 fusion protein consists of Cre recombinase fused to a triple mutant form of the human estrogen receptor which does not bind its natural ligand (17β-estradiol) at physiological concentrations but will bind the synthetic estrogen receptor ligands 4-hydroxytamoxifen (OHT or tamoxifen) and, with lesser sensitivity, ICI 182780. Restricted to the cytoplasm, Cre-ERT2 can only gain access to the nuclear compartment after exposure to tamoxifen. To counteract the mixed estrogen agonist effects of tamoxifen injections, which can result in late fetal abortions in pregnant mice, progesterone may be coadministered.

Development

CRISPR/Cas9 genome editing was used to insert a Cre-ERT2 fusion protein followed by a GSG linker and a P2A peptide (for production of a bicistronic mRNA transcript) immediately after the first codon ATG in exon 2 of the Myh11 gene on the chromosome 16. Cas9 nuclease, single guide RNA, and a long double-stranded DNA donor vector were introduced into embryos derived from C57BL/6J females, and then transferred to pseudopregnant females. Progeny were bred to C57BL/6J males for germline transmission and maintained on the C57BL/6J background. Upon arrival, mice were bred to C57BL/6J (Stock 000664) for at least one generation to establish the colony.

Allele

Symbol: Myh11^{em2(cre/ERT2)Jifz}
Name: endonuclease-mediated mutation 2, Jifeng Zhang
MGI accession ID: MGI:7512810
Generation method: Endonuclease-mediated
Attributes: Recombinase-expressing; Inducible
Synonyms: Myh11-CreER^T2-P2A
Marker symbol: Myh11
Marker name: myosin, heavy polypeptide 11, smooth muscle
Marker synonyms: AAT4; FAA4; SM1; SM2; SMHC; SMMHC; SMMS-1; VSCM2
Chromosome: 16
Strain of origin: C57BL/6J
Molecular note: Using CRISPR/Cas9 technology, a cre/ERT2-P2A sequence was inserted into the endogenous Myh11 gene immediately after the first codon ATG in exon 2.