STOCK Grm7^{Tg(SMN2)89Ahmb} Smn1^{tm3(SMN2/Smn1)Mrph} Tg(SMN2*delta7)4299Ahmb/J

Stock number: 007951
Product name: SMNΔ7;SMN2;Smn^Res , SMNΔ7;SMN2;Smn^COIN , Moderate Type II SMA Rescue , Delta 7 mouse with hybrid rescue allele
Research areas: Neurobiology Research

Description

This triple mutant mouse strain harbors two human SMN2 transgenic alleles and a single Smn1 targeted mutation, and may be useful in studies of Spinal Muscular Atrophy.

Detailed description

This triple mutant mouse harbors two transgenic alleles and a single targeted mutation. The Tg(SMN2*delta7)4299Ahmb allele consists of a human SMN2 (survival of motor neuron 2, centromeric) cDNA lacking exon 7 whereas the Tg(SMN2)89Ahmb allele consists of the entire human SMN2 gene. Mice that are homozygous for the targeted mutant Smn1^{tm3(SMN2/Smn1/SMN2)Mrph} allele and homozygous for the two transgenic alleles should function similarly to SMA mutant strain FVB.Cg-Tg(SMN2*delta7)4299Ahmb Tg(SMN2)89Ahmb Smn1^tm1Msd/J (Stock No. 005025). The targeted mutant Smn1^{tm3(SMN2/Smn1/SMN2)Mrph} allele is engineered to revert to a fully functional Smn1 allele upon Cre-mediated recombination. This mutant mouse strain may be useful in studies of Spinal Muscular Atrophy.

Importation of this model was supported by the Spinal Muscular Atrophy Foundation.

Development

The transgenic alleles were created in the laboratory of Dr. Arthur Burghes at Ohio State University. A 35.5 kb BamHI genomic fragment encoding the human SMN2 (survival of motor neuron 2, centromeric) promoter and gene (derived from genomic clone PAC215P15) was injected into fertilized FVB/N mouse oocytes and founder animal 89 was obtained. Similarly, a human SMN2 cDNA (SMNdelta7) lacking exon 7 under the control of the human SMN2 promoter was microinjected into fertilized FVB/N oocytes and founder animal 4299 was obtained. These double mutants were in turn mated with mice bearing the Smn1^{tm3(SMN2/Smn1/SMN2)Mrph} targeted mutation. The 129S6/SvEvTac X C57BL/6Tac hybrid derived F1H4 ES cell line was used to generate the targeted mutation.

Allele

Symbol: Tg(SMN2*delta7)4299Ahmb
Name: transgene insertion 4299, Arthur H M Burghes
MGI accession ID: MGI:3056918
Generation method: Transgenic
Attributes: Inserted expressed sequence; Humanized sequence
Marker symbol: Tg(SMN2*delta7)4299Ahmb
Marker name: transgene insertion 4299, Arthur H M Burghes
Chromosome: UN
Strain of origin: FVB/N
Expressed genes: SMN2,survival of motor neuron 2, centromeric,human
Site of expression: Tg(SMN2*delta7)4299Ahmb
Molecular note: The transgene contains a human SMN2 promoter and a human SMN2 cDNA (SMNdelta7) that lacks exon 7. There are 14 copies of this allele integrated into the genome.

Allele

Symbol: Smn1^{tm3(SMN2/Smn1)Mrph}
Name: targeted mutation 3, Andrew Murphy
MGI accession ID: MGI:3794199
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); Humanized sequence; No functional change
Marker symbol: Smn1
Marker name: survival motor neuron 1
Chromosome: 13
Strain of origin: (129S6/SvEvTac x C57BL/6NTac)F1
Site of expression: Following Cre-mediated irreversible inversion of the fragment bordered by the lox71 and lox66 sites, the allele is "rescued" into a format that contains mouse Smn1 exons 1 through 7 and human SMN2 exon 8 and the resulting SMN protein is produced in motor neurons.
Molecular note: Exons 7 and 8 of the mouse Smn1 (survival motor neuron 1) gene and a several hundred base pairs of flanking sequence were replaced with a fragment containing, in order: 1) an inverted lox71 site; 2) exon 7 from the human SMN2 (survival of motor neuron 2, centromeric) gene flanked by several hundred base pairs of intron sequence; 3) an inverted copy of mouse Smn1 exon 7 flanked by several hundred base pairs of intron sequence; 4) a lox66 site; 5) an FRT site remnant from a deleted selection cassette; and 6) human SMN2 exon 8 including the 3'UTR and polyA signal with several hundred base pairs of flanking sequence. The engineered allele expresses a hybrid Smn1 gene containing mouse Smn1 exons 1 through 6 and human SMN2 exons 7 and 8. The human SMN2 exon 7 is skipped in the majority of mRNA derived from the hybrid gene due to a single base pair difference in human SMN2 exon 7, compared to human SMN1 exon 7. Following Cre-mediated irreversible inversion of the fragment bordered by the lox71 and lox66 sites, the allele is "rescued" into a format that contains mouse Smn1 exons 1 through 7 and human SMN2 exon 8. Because the mouse Smn1 exon 8 is efficiently spliced, the majority of the mRNA from the rescue allele after Cre-mediated inversion contains mouse Smn1 exon 7.

Allele

Symbol: Grm7^{Tg(SMN2)89Ahmb}
Name: transgene insertion 89, Arthur H M Burghes
MGI accession ID: MGI:2448989
Generation method: Transgenic
Attributes: Hypomorph; Inserted expressed sequence; Humanized sequence
Marker symbol: Grm7
Marker name: glutamate receptor, metabotropic 7
Chromosome: 6
Strain of origin: FVB/N
Expressed genes: SMN2,survival of motor neuron 2, centromeric,human
Site of expression: Human SMN2 protein is expressed in the tissues examined (brain, liver, spinal cord) [Stock No. 005024].
Molecular note: A 35.5 kb genomic fragment containing the human survival motor neuron 2 (SMN2) gene and promoter was used for the transgene. The transgene is ubiquitously expressed in all tissues examined by Northern blot analysis. Line 89 carries 1 copy of the transgene integrated into intron 4 of the gene. RT-PCR confirmed reduced expression of the gene the transgene is integrated into.