B6N.Cg-Ldb3^tm1.1Amank/J

Stock number: 036433
Product name: Lbd3^A165V, Lbd3^Ala165Val
Research areas: Neurobiology Research

Description

Ldb3^Ala165Val knockin mice carry the dominant Ala165Val amino acid substitution in the Ldb3 (LIM domain binding 3) gene. Heterozygous mice develop muscle weakness, as well as Z-disc myofibrillar disruption and protein aggregation in skeletal muscle. These mice may be useful for studying myofibrillar myopathies (MFMs).

Detailed description

Ldb3 (LIM domain binding 3) encodes a PDZ domain and 3 LIM domains-containing protein involved in modulating mechanical stress signaling in the Z-disc domain of skeletal muscle. The dominant p.Ala165Val mutation has been identified in several families of European descent and is associated with myofibrillar myopathies (MFMs). The Ala165Val mutation is conserved with an overall amino acid identity of >92% for LDB3 isoforms between mice and humans. Mice heterozygous and homozygous for the mutation are viable and fertile. Heterozygous Ldb3^Ala165Val mice develop progressive muscle weakness (grip strength test) beginning at 6 months of age. Skeletal muscle pathologies identified in heterozygotes resemble MFM pathologies and are characterized by Z-disc myofibrillar disruption, progressive protein aggregation, rimmed vacuoles, and increased lysosomal autophagy. Cardiac ventricular muscle fibers are not affected. These mice may be useful for studying myofibrillar myopathies.

Development

The Ldb3^Ala165Val knock-in allele was created by Dr. Ami Mankodi at NINDS in collaboration with Dr. Shyam Sharan at NCI. The targeting vector was designed to insert an amino acid substitution at position 165 altering alanine to valine (A165V; chr14:34571772 C>T; GRCm38/mm10) into exon 6 of the Ldb3 (LIM domain binding 3) gene on chromosome 14. The substitution was followed by a loxP-flanked neomycin cassette in intron 6. The construct was electroporated into (C57BL/6J x 129S4/SvJae)F1-derived V6.4 embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts. The resulting chimeric animals were bred to C57BL/6N-Tg(ACTB-cre)3Mrt mice to remove the neomycin cassette. Progeny were backcrossed to C57BL/6N mice for at least 10 generations and the cre allele removed by the donating laboratory (see SNP note below). 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).

In 2021, 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 sent to The Jackson Laboratory Repository. One of the 43 markers throughout the genome, on Chromosome 11, was still found to be segregating with 129.

Allele

Symbol: Ldb3^tm1.1Amank
Name: targeted mutation 1.1, Ami Mankodi
MGI accession ID: MGI:6712785
Generation method: Targeted
Attributes: Humanized sequence
Synonyms: Ldb3^Ala165Val
Marker symbol: Ldb3
Marker name: LIM domain binding 3
Marker synonyms: CMD1C; CMD2L; CMH24; CMPD3; cypher; LDB3Z1; LDB3Z4; LVNC3; MFM4; ORACLE; PDLIM6; RGD1564875; ZASP
Chromosome: 14
Strain of origin: (C57BL/6J x 129S4/SvJae)F1
Molecular note: The targeting vector is designed to insert an amino acid substitution at position 165 altering alanine to valine (A165V; chr14:34571772 C to T; GRCm38/mm10) into exon 6. The substitution is followed by a loxP-flanked neomycin cassette in intron 6. Cre-mediated recombination removed the loxP-flanked neo cassette.