STOCK Lmna^tm1.1Hjw/J

Stock number: 037310
Product name: Lmna^L648R
Research areas: Developmental Biology Research, Internal/Organ Research

Description

Lmna^L648R knock-in mice express an L648R (leucine to arginine) amino acid substitution in the Lmna (lamin A) locus. Mice homozygous for the mutation exhibit cranial, mandibular, and dental defects, as well as a slightly shortened lifespan. This strain may be useful for studies of aging.

Detailed description

Lmna (lamin A) encodes prelamin A, the precursor of lamin A, and lamin C, intermediate filament proteins, which, with B-type lamins, form the nuclear lamina. The mature lamin A protein is generated by a series of posttranslational processing reactions initiated by the prelamin A carboxyl-terminal CAAX (cysteine-aliphatic-aliphatic-any amino acid) motif and a final cleavage reaction (catalyzed by the zinc metallopeptidase, ZMPSTE24) that removes the last 15 amino acids including its farnesylated cysteine. Accumulation of prelamin A is associated with aging.

Lmna^L648R knock-in mice express an L648R (leucine to arginine) amino acid substitution in the ZMPSTE24 cleavage site of prelamin A. The mutation corresponds to the human L647R mutation; a patient with this mutation exhibited a mild progeroid disorder. Homozygous Lmna^L648R mice express only farnesylated prelamin A and no mature lamin A protein. Expression of the splice variant lamin C is not affected. Mice exhibit lower body mass by 10 weeks of age, and by 20-30 weeks of age they develop aberrant zygomatic arches, mandibular degeneration, mild dental malocclusion, decreased vertebral bone mass, long bone defects, and reduced body fat (by 52 weeks). Most mice live to 65-70 weeks with 40% of males and 75% of females living to 90 weeks of age. Homozygotes are viable, but are not fertile.

Development

The targeting vector contains a leucine to arginine amino acid substitution at position 648 (L648R; CTC to CGC) inserted into exon 11 and an FRT-flanked PGK-neomycin/kanamycin resistance cassette inserted into intron 11 of the Lmna (lamin A) gene on chromosome 3. The mutation substitutes a hydrophobic residue for arginine at the ZMPSTE24 cleavage site in prelamin A. The construct was electroporated into (C57BL/6J x 129S6/SvEvTac)F1-derived KV1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6J blastocysts. The resulting male chimeras were crossed to C57BL/6J females and progeny were crossed to B6.Cg-Tg(ACTFLPe)9205Dym/J (Stock No. 005703) to remove the neo cassette. The strain has been backcrossed to C57BL/6J for at least 6 generations by the donating laboratory (see SNP note below). Upon arrival, mice were bred to C57BL/6J for at least 1 generation to establish the colony.

In 2022, 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 males shipped to The Jackson Laboratory Repository. Two of the 43 markers throughout the genome were segregating with 129, suggesting an incomplete backcross.

Allele

Symbol: Lmna^tm1.1Hjw
Name: targeted mutation 1.1, Howard J Worman
MGI accession ID: MGI:6887957
Generation method: Targeted
Attributes: Not Specified
Marker symbol: Lmna
Marker name: lamin A
Chromosome: 3
Strain of origin: (C57BL/6J x 129S6/SvEvTac)F1
Molecular note: The targeting construct replaced exon 11 with one in which a point mutation (CTC to CGC) results in the amino acid substitution of of leucine to arginine at position 648 (L648R). Flp-mediated recombination removed the selection cassette.