B6N.129S1(FVB)-Emd^tm1.1Stw/LammJ

Stock number: 032137
Product name: EMD knock-out , Emd^Stw2 , Emd^- , Emerin-KO
Research areas: Apoptosis Research, Cell Biology Research, Neurobiology Research, Research Tools

Description

EMD knock-out mice (Emd^Stw2, Emd^-, Emerin-KO) have a deletion of the emerin coding regions in exons 2-5. Emerin-deficient females (Emd^-/-) and males (Emd^-/Y) may be useful for studying actin dynamics/polymerization, nuclear stability, mechanotransduction signaling, muscle repair and Emery-Dreifuss muscular dystrophy (EDMD).

Detailed description

Emerin (EMD) is a nuclear envelope gene on the X chromosome, the loss of which is associated with Emery-Dreifuss muscular dystrophy (EDMD).

The EMD knock-out allele (Emd^Stw2, Emd^-, Emerin-KO) has a deletion of the emerin coding regions in exons 2-5. Unlike human patients with emerin mutations, these emerin-deficient mice lack an overt muscular phenotype - but show defective muscle regeneration both in vivo and in vitro. Specific details are below.

This EMD knock-out allele has a loss of Emd mRNA (as confirmed by northern blot and by immunostaining of fibroblast nuclei). Emerin-deficient females (Emd^-/-) and males (Emd^-/Y) are viable and fertile, with no reported abnormalities in growth, behavior, reproduction or locomotion. Furthermore, histological analyses revealed no overt pathology or any indication of muscle atrophy, dystrophy or any cardiac pathology, even in relatively old mice (~1 year).

In a cardiotoxin-induced model of muscle regeneration, Emd^-/Y animals show delayed muscle repair when compared to controls. [Melcon et al. 2006 Hum Mol Genet 15:637]

Cells isolated from Emd^-/Y mice show defects in nuclear stability and mechanotransduction signaling [Ho et al. 2013 Nature 497:507], as well as defective nucleo-cytoskeletal coupling and myoblast differentiation. [Melcon et al. 2006 Hum Mol Genet 15:637]

Development

This EMD knock-out allele (Emd^Stw2, Emd^-, Emerin-KO) was generated by Dr. Colin L. Stewart (while at NCI Frederick). First, a targeting vector was designed to place a loxP-flanked PGK-Neo^R cassette upstream of exon 2, and a loxP site in the 5' UTR of exon 5 of the emerin locus (Emd) on the X chromosome. The construct was electroporated into 129S1/Sv-Oca2⁺ Tyr⁺ Kitl⁺-derived W9.5 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts, and chimeric animals were bred with C57BL6/N mice for germline transmission of the EMD floxed allele (Emd^Stw1). Dr. Stewart reports that EMD floxed mice were bred with ACTB-Cre transgenic mice (on C57BL/6N genetic background; see Stock No. 019099) for germline deletion of all the floxed sequences. The resulting EMD knock-out allele (Emd^Stw2) has the exons 2-5 coding region deleted with a single loxP site remaining in the 5' UTR of exon 5. The EMD knock-out colony was maintained on a mixed C57BL/6;129 genetic background for several generations (and the ACTB-Cre transgene was also removed) until 2006, when the EMD knock-out mice were sent to Dr. Jan Lammerding (Cornell University). Dr. Lammerding maintained the colony by backcrossing to C57BL/6NCrl for more than 20 generations, and then sent hemizygous males (black coat color) to The Jackson Laboratory Repository in 2018. Upon arrival, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6NJ oocytes (Stock No. 005304).
Of note, Dr. Lammerding reports that, at least once during backcrossing, a heterozygous female was bred to a C57BL/6N inbred male (thus the Y chromosome of the congenic strain is of C57BL/6N origin).

Allele

Symbol: Emd^tm1.1Stw
Name: targeted mutation 1.1, Colin L Stewart
MGI accession ID: MGI:3621266
Generation method: Targeted
Attributes: Null/Knockout
Synonyms: Emd^stw2
Marker symbol: Emd
Marker name: emerin
Marker synonyms: CMD3C; EDMD; LEMD5; STA
Chromosome: X
Strain of origin: 129S1/Sv-Oca2⁺ Tyr⁺ Kitl⁺
Molecular note: A floxed PgkNeo cassette was inserted in intron 1. A third loxP site was also inserted in the 3' untranslated region of exon 5. Cre mediated recombination was then used to remove exons 2 through 5 from mice in which the gene was correctly targeted. Northern blot analysis failed to detect transcript in mutant heart and muscle samples.