FVB.Cg-Mapk10^tm1Flv Grm7^{Tg(SMN2)89Ahmb} Smn1^tm1Msd Tg(SMN2*delta7)4299Ahmb/LganJ

Stock number: 030970
Product name: SMA-J3
Research areas: Apoptosis Research, Developmental Biology Research, Neurobiology Research, Research Tools

Description

A targeted knock-out of the Mapk10 (JNK3) gene ameliorates the spinal muscular atrophy phenotype associated with the FVB.Cg-Grm7^{Tg(SMN2)89Ahmb} Smn1^tm1Msd Tg(SMN2*delta7)4299Ahmb/2J (Stock No. 005025) strain.

Detailed description

Mapk10 (mitogen-activated protein kinase 10; also called JNK3) is one of several MAP kinases showing increased phosphorylation in both spinal muscular atrophy (SMA) patients and mouse models of SMA.

These SMA-J3 compound mutant mice combine a Mapk10/JNK3 knock-out allele with an established compound mutant model of SMA that incorporates Grm7^{Tg(SMN2)89Ahmb}, Smn1^tm1Msd , and Tg(SMN2*delta7)4299Ahm (see Stock No. 005025). Stock No. 005025 mice that are homozygous for the targeted mutant Smn allele and homozygous for the two transgenic alleles (Grm7^{Tg(SMN2)89Ahmb} and Tg(SMN2*delta7)4299Ahmb) exhibit symptoms and neuropathology similar to patients afflicted with proximal spinal muscular atrophy (SMA). Triple homozygous mice on the FVB/N genetic background are noticeably smaller than normal littermates at birth and show progressive muscle weakness.

Adding the Mapk10 (JNK3) deficiency to the above triple mutant line reduces degeneration of cultured neurons caused by low levels of SMN protein. Genetic inhibition of the JNK pathway in vivo by the Mapk10 knock-out results in amelioration of the SMA phenotype. MAPK10/JNK3 deficiency prevents the loss of spinal cord motor neurons, reduces muscle degeneration, improves muscle fiber thickness and muscle growth, improves motor function and overall growth, and increases lifespan of mice with SMA.

SMA-J3 mice homozygous for all 4 mutations live a reported 14.95 +/- 0.79 days. Triple homozygous SMA mutants carrying wildtype Mapk10/Jnk3 survive an average of 7.14 +/- 0.93 days. Knock-out of the Mapk10/Jnk3 gene results in a 45% increase in lifespan in this SMA mouse model.

Evidence suggests a systemic rescue of phenotype by an SMN-independent mechanism. The publishing lab proposes that MAPK10/JNK3 may represent a possible SMA therapeutic target.

Development

FVB.Cg-Grm7^{Tg(SMN2)89Ahmb}Smn1^tm1Msd Tg(SMN2*delta7)4299Ahmb/2J (Stock No. 005025) mice were intercrossed with B6.129S1-Mapk10^tm1Flv/J (Stock No. 004322) animals that had been backcrossed to FVBN/J for 10 generations.

In brief:

Smn1^tm1Msd: The mouse Smn gene was disrupted with a neomycin cassette and a lacZ gene fused to the first 40 nucleotides of exon 2.

Grm7^{Tg(SMN2)89Ahmb}: 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.

Tg(SMN2*delta7)4299Ahmb: 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.

Mapk10^tm1Flv: Protein subdomains VIII and IX (amino acid residues 189-267) of the mouse Mapk10 (JNK3) gene, encoding the tripeptide dual phosphorylation motif required for protein kinase activity, were replaced with a neomycin cassette to create a knock-out allele.

This compound mutant strain is on a congenic FVB/N genetic background.

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
Synonyms: SMNdelta7; Tg(SMN1*delta7)4299Ahmb
Marker symbol: Tg(SMN2*delta7)4299Ahmb
Marker name: transgene insertion 4299, Arthur H M Burghes
Marker synonyms: SMNdelta7; Tg(SMN1*delta7)4299Ahmb
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: 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: Mapk10^tm1Flv
Name: targeted mutation 1, Richard A Flavell
MGI accession ID: MGI:2176237
Generation method: Targeted
Attributes: Null/Knockout
Synonyms: Jnk3-
Marker symbol: Mapk10
Marker name: mitogen-activated protein kinase 10
Marker synonyms: C230008H04Rik; Jnk3; JNK3A; p493F12; p54bSAPK; PRKM10; SAPb; SAPK1b; SAPKC; Serk2
Chromosome: 5
Strain of origin: 129S1/Sv-Oca2⁺ Tyr⁺ Kitl⁺
Molecular note: A neomycin resistance cassette replaced a genomic fragment containing sequences corresponding to amino acids 211-267, which encode the tripeptide dual phosphorylation motif required for protein kinase activity. Northern blot and RT-PCR analysis on total brain RNA derived from homozygous mice demonstrated that no detectable transcript is produced from this allele. Enzymatic activity assays on extracts derived from hippocampus of homozygous mice confirmed that no functional protein was expressed from this allele.

Allele

Symbol: Smn1^tm1Msd
Name: targeted mutation 1, Michael Sendtner
MGI accession ID: MGI:2183946
Generation method: Targeted
Attributes: Reporter; Null/Knockout
Synonyms: SMN^-
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: 129P2/OlaHsd
Expressed genes: lacZ,beta-galactosidase,E. coli
Site of expression: The expression of the lacZ gene in tissues where Smn is normally expressed was noted.
Molecular note: A lacZ-neo cassette was inserted into exon 2 by homologous recombination resulting in an in-frame fusion of lacZ to exon 2. Homozygous mutant embryos were identified up to 80 hours post coitum. The expression of the lacZ gene in tissues where Smn is normally expressed was noted.