STOCK Grm7^{Tg(SMN2)89Ahmb} Smn1^tm1Jme/J

Stock number: 033847
Product name: SMN2;SMN^F7 [or Tg(SMN2)89;SMN^F7]
Research areas: Developmental Biology Research, Neurobiology Research, Research Tools

Description

SMN2;SMN^F7 double mutant mice (also called Tg(SMN2)89;SMN^F7) harbor a human SMN2 transgene and the SMN^F7 floxed allele. Exposure to Cre recombinase removes the floxed sequence (Smn1 exon 7) - creating a null allele. These SMN2;SMN^F7 mice may be useful for Cre-inducible studies related to human spinal muscular atrophy (SMA) or other neuromuscular degenerative diseases.

Detailed description

These SMN2;SMN^F7 double mutant mice (also called Tg(SMN2)89;SMN^F7) harbor a human SMN2 transgene (Tg(SMN2)89) and the SMN^F7 floxed allele.
The Tg(SMN2)89 transgene sequence encoding the entire human SMN2 gene is inserted into the glutamate receptor metabotropic 7 locus (Grm7) on chromosome 6.
The SMN^F7 floxed allele has a neomycin resistance cassette within intron 6 and loxP sites immediately flanking exon 7 of the survival motor neuron 1 locus (Smn1) on chromosome 13. This floxed allele exhibits no transcript splicing defects (see Stock No. 006146).

Prior to introduction of Cre recombinase, mice homozygous for both alleles (SMN2^+/+;SMN^F7/F7) are viable and fertile with no reported gross physical or behavioral abnormalities.

When SMN2;SMN^F7 are bred to mice that express Cre recombinase, the resulting offspring will have Smn1 exon 7 deleted - creating a null allele in the cells/tissues as determined by the Cre promoter. As mutations of this exon are implicated in 95% of all human spinal muscular atrophy (SMA), these mice may be useful in studying SMA or other neuromuscular degenerative diseases. For example, other mouse lines harboring this Tg(SMN2)89 transgene and homozygous for a different Smn1 knock-out allele (Stock No. 005024) exhibit symptoms and neuropathology similar to patients afflicted with type I proximal SMA.

Development

These SMN2;SMN^F7 double mutant mice (Stock No. 033847; also called Tg(SMN2)89;SMN^F7) harbor a human SMN2 transgene and the SMN^F7 floxed allele.

The human SMN2 transgene (Tg(SMN2)89; Grm7^{Tg(SMN2)89Ahmb}) was created in the laboratory of Dr. Arthur H. M. Burghes (The Ohio State University). A 35.5 kb BamHI genomic fragment encoding the human SMN2 promoter and gene (derived from genomic clone PAC215P15) was injected into fertilized FVB/N mouse oocytes and founder animal 89 was obtained. One copy of the transgene integrated into intron 4 of the glutamate receptor metabotropic 7 locus (Grm7) on chromosome 6. Mice harboring this transgene were backcrossed to FVB/N at least five generations (Stock No. 005024), and then females homozygous for Tg(SMN2)89 and wildtype at the Smn1 locus were used as described below.

The SMN^F7 floxed allele (Smn1^tm1Jme) was designed by Dr. Judith Melki (Genopole, Inserm) to have a neomycin resistance cassette within intron 6 and loxP sites immediately flanking exon 7 of the survival motor neuron 1 locus (Smn1) on chromosome 13. This targeting vector was electroporated into "129Sv" embryonic stem cells. Chimeric males were bred to C57BL/6J females. C57BL/6J-congenic males (N10) homozygous for this floxed allele (Stock No. 006146) were used as described below.

To generate the SMN2;SMN^F7 double mutant line (Stock No. 033847), sperm homozygous for the SMN^F7 floxed allele (from Stock No. 006146) was used to fertilize oocytes homozygous for Tg(SMN2)89 and wildtype at the Smn1 locus (from Stock No. 005024). The live colony (mixed FVB/N;C57BL/6J genetic background) was then maintained by breeding the double mutant mice together.

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
Synonyms: SMN2; Tg(SMN2)89Ahmb
Marker symbol: Grm7
Marker name: glutamate receptor, metabotropic 7
Marker synonyms: 6330570A01Rik; E130018M02Rik; GLUR7; Gpr1g; GPRC1G; MGLU7; mGlu7a receptor; mGluR7; NEDSHBA; PPP1R87
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.

Allele

Symbol: Smn1^tm1Jme
Name: targeted mutation 1, Judith Melki
MGI accession ID: MGI:2384151
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); No functional change
Synonyms: SMN^F7
Marker symbol: Smn1
Marker name: survival motor neuron 1
Marker synonyms: BCD541; C-BCD541; GEMIN1; SMA; SMA@; SMA1; SMA2; SMA3; SMA4; Smn; SMNC; SMNT; T-BCD541; TDRD16A; TDRD16B
Chromosome: 13
Strain of origin: 129
Molecular note: A floxed exon 7 and neomycin resistance cassette were introduced to the gene via homologous recombination. The floxed exon 7 and neo cassette do not appear to interfere with transcript splicing in mutant animals as determined by RT-PCR analysis.