C57BL/6J-Tg(Ckm-Mir486)2Lmk/MsalxJ

Stock number: 030449
Product name: MCK-miR-486 Tg , Tg(Cmk-Mir486) , MCK-Tg[Cmk-Mir486] , Tg(Ckm-Mir486)#Lmk
Research areas: Neurobiology Research

Description

MCK-miR-486 Tg mice (also called Tg(Cmk-Mir486) or MCK-Tg[Cmk-Mir486]) have heart and skeletal muscle myofiber overexpression of miR-486 - a muscle-enriched microRNA that is markedly downregulated/reduced in the muscles of Duchenne muscular dystrophy (DMD) patients and dystrophin-deficient mice.

Detailed description

MicroRNA-486 (miR-486) has been identified as a muscle-enriched microRNA that is markedly downregulated/reduced in the muscles of Duchenne muscular dystrophy (DMD) patients and dystrophin-deficient mice (e.g., Dmd^mdx-5Cv mice).
The MCK-miR-486 transgene (also called Tg(Cmk-Mir486) or MCK-Tg[Cmk-Mir486]) has the mouse muscle creatine kinase promoter/enhancer sequences directing expression of mouse miR-486 exclusively in the heart and skeletal muscle myofibers (but not in muscle satellite cells). To date (May 2017), it has not been attempted to make this strain homozygous. The phenotype of hemizygous C57BL/6J MCK-miR-486 Tg mice is described below.
The donating investigator reports that C57BL/6J MCK-miR-486 Tg mice from founder line 2 overexpress miR-486 transcript at levels 2-4-fold greater than their wild-type (non-carrier) littermates. C57BL/6J MCK-miR-486 Tg mice are viable and fertile, with no reported gross physical or behavioral abnormalities compared to non-carrier mice at six months of age - other than a slight increase in weight that is maintained for the remainder of their lifespan. When subjected to cardiotoxin (CTX)-induced tibialis anterior muscle injury protocol, the MCK miR-486 Tg mice have delayed skeletal muscle regenerative capacity and dysregulation of miR-486 downstream target genes (including PTEN/AKT signaling components).
When combined with Dmd^mdx-5Cv (see Stock No. 002379 for allele description), the resulting C57BL/6J-Dmd^{mdx-5Cv/mdx-5Cv} Tg(Cmk-Mir486) mice have muscle-specific miR-486 overexpression in Dmd^{mdx-5Cv/mdx-5Cv} muscle. This results in reduced serum creatine kinase levels, improved sarcolemmal integrity, fewer centralized myonuclei, increased myofiber size and improved muscle physiology and performance.

Development

MCK-miR-486 Tg mice (also called Tg(Cmk-Mir486) or MCK-Tg[Cmk-Mir486]) were created in the laboratory of Dr. Louis M. Kunkel (Boston Children's Hospital). The MCK-miR-486 transgene was designed to have the ~6.5 kbp promoter/enhancer region from the mouse muscle creatine kinase gene (Ckm) followed by a 500 bp fragment containing the stem loop precursor sequence from the mouse microRNA 486 gene (Mir486; C57BL/6J origin) and an SV40 polyA sequence. Specifically, the ~6.5 kbp Ckm genomic DNA fragment contains the promoter and enhancer 1, untranslated exon 1, 3 kbp of intron 1 (including the enhancer 2 region) and the first 16 bp of exon 2. The final ~7 kbp transgene was injected into the pronucleus of C57BL/6J fertilized eggs. Founder animals were bred to C57BL/6J inbred mice for germline transmission. Founder line 2 was identified with miR-486 transcript expression levels more than two-fold greater than their wild-type (non-carrier) littermates (and had the strongest muscle expression of miR-486) - this founder line was maintained on the C57BL/6J genetic background. MCK-miR-486 Tg males were bred to C57BL/6J females for approximately ten generations, and then Dr. Kunkel sent some MCK-miR-486 Tg mice with black coat color to Dr. Matthew S. Alexander (University of Alabama at Birmingham) in 2016. There, the MCK-miR-486 Tg colony was further backcrossed to C57BL/6J mice for five generations prior to sending males with black coat color to The Jackson Laboratory Repository in 2018. Upon arrival, sperm was cryopreserved. To establish our living colony, an aliquot of the frozen sperm was used to fertilize oocytes from C57BL/6J inbred females (Stock No. 000664).
Of note, the transgene insertion site(s) and copy number are not known to date (May 2017).

Allele

Symbol: Tg(Ckm-Mir486)2Lmk
Name: transgene insertion 2, Louis M Kunkel
MGI accession ID: MGI:5607528
Generation method: Transgenic
Attributes: Inserted expressed sequence
Marker symbol: Tg(Ckm-Mir486)2Lmk
Marker name: transgene insertion 2, Louis M Kunkel
Chromosome: UN
Strain of origin: C57BL/6J
Expressed genes: Mir486,microRNA 486,mouse, laboratory
Site of expression: Heart and skeletal muscle myofibers.
Molecular note: A 500-bp fragment containing the stem loop precursor sequence of mouse miR-486was placed under the control of the mouse creatine kinase promoter.