B6.Cg-Myh11^{em1(icre)Jifz}/J

Stock number: 038823
Product name: Myh11-CreNLS^P2A
Research areas: Research Tools

Description

Myh11-CreNLS^P2A knock-in mice carry a codon optimized Cre recombinase (icre) fused to ERT2 inserted into the Myh11 (myosin, heavy polypeptide 11, smooth muscle) locus. Please note: tamoxifen administration does not further augment Cre activity, necessitating its use as a constitutive Cre model.  Mice have constitutive cre expression in smooth muscle cells without disrupting endogenous Myh11 expression. This strain may be useful for research involving smooth muscle cells and smooth muscle cell-dependent cardiovascular diseases.

Of note, the inducible Myh11-CreER^T2-PA is distributed as B6.Cg-Myh11^{em2(cre/ERT2)Jifz}/J (Stock No. 038824).

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 involuntarily in the lining of internal organs such as blood vessels, stomach and intestines.

Myh11-CreNLS^P2A knock-in mice carry a codon optimized Cre recombinase (icre) fused to ERT2 with a nuclear localization signal (NLS) and a P2A peptide inserted after the ATG of the Myh11 (myosin, heavy polypeptide 11, smooth muscle) locus. Incorporating the NLS guarantees consistent nuclear translocation of the CreERT2 recombinase, even in the absence of estrogen receptor ligands. As validated using reporter mice, tamoxifen administration does not further augment Cre activity, necessitating its use as a constitutive Cre model. The mutation has a minimal impact on endogenous Myh11 mRNA and protein levels. Mice homozygous for the mutation are viable and fertile, but have not been used for breeding. When cre-positive 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. 007676) progeny exhibit EGFP fluorescence (and decreased TdTomato fluorescence) in aorta, bladder and jejunum. Cre recombinase activity is absent in cardiomyocytes and skeletal muscles. In comparison to transgenic Myh11-cre strains, this strain expresses cre from the endogenous Myh11 promoter and is not located on the Y chromosome. This strain may provide an improved model for smooth muscle cell targeted gene deletion.

Of note, the inducible Myh11-CreER^T2-PA is distributed as B6.Cg-Myh11^{em2(cre/ERT2)Jifz}/J (Stock No. 038824).

Development

CRISPR/cas9 genome editing was used to insert a nuclear localization sequence (NLS) followed by a codon optimized Cre recombinase fused to ERT2, 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. Please note: tamoxifen administration does not further augment Cre activity, necessitating its use as a constitutive Cre model. Cas9 nuclease, single guide RNA, and a long double stranded DNA donor vector were introduced into fetilized eggs derived from C57BL/6J X SJL/J hybrid females, and then transferred to pseudopregnant females. Progeny were bred to C57BL/6J males for germline transmission and the male offspring were backcrossed for 8 generation to C57BL/6J by the donating laboratory (see SNP note below). Upon arrival, mice were bred to C57BL/6J (Stock No. 000664) for at least one generation to establish the colony.

in 2023, a 48 SNP (single nucleotide polymorphism) panel analysis, with 43 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. Two of the 43 markers throughout the genome were segregating with SJL (on Chromosomes 8 and 9), suggesting an incomplete backcross.

Allele

Symbol: Myh11^{em1(icre)Jifz}
Name: endonuclease-mediated mutation 1, Jifeng Zhang
MGI accession ID: MGI:7512809
Generation method: Endonuclease-mediated
Attributes: Recombinase-expressing
Synonyms: Myh11^em1(cre)Jifz; Myh11-CreNLS^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 x SJL
Molecular note: Using CRISPR/Cas9 technology, a a nuclear localization sequence (NLS) followed by a codon optimized Cre recombinase fused to ERT2, a GSG linker and a P2A peptide (for production of a bicistronic mRNA transcript) immediately was inserted into the endogenous Myh11 gene immediately after the first codon ATG in exon 2. Cre expression is constitutive rather than inducible by tamoxifen.