B6.129S4(FVB)-Ppargc1a^tm1Brsp/J

Stock number: 008597
Product name: PGC-1alpha KO
Research areas: Cardiovascular Research, Developmental Biology Research, Diabetes and Obesity Research, Metabolism Research, Neurobiology Research, Research Tools

Description

Mice that are homozygous for this Ppargc1a (peroxisome proliferative activated receptor, gamma, coactivator 1 alpha) knock-out mutation exhibit some postnatal lethality, impaired mitochondrial function and gluconeogenesis, are hypermetabolic, hyperactive, and sensitive to cold temperatures. This mutant mouse strain may be useful in studies of metabolic homeostasis, resistance to obesity, hyperactivity and behavior, mitochondrial impairment and neurodegeneration, and heart failure.

Detailed description

Mice that are homozygous for this targeted mutation are fertile, normal in size and do not display any gross physical or behavioral abnormalities. Approximately half of homozygotes exhibit postnatal lethality. The Donating Investigator reports maintaining homozygous pups at a higher temperature (77°F) increases their survival. No gene product (mRNA or protein) is detected by RNA hybridization, real-time PCR analysis of skeletal muscle or liver, or Western blot analysis of brown fat. Histological examination of the brown fat from homozygotes reveals abnormal accumulation of large lipid droplets. Examination of brain tissue shows spongiform lesions and gliosis. When fed a high fat diet homozygotes have increased insulin sensitivity, glucose tolerance and reduced body weight. After 24 hours of fasting, homozygotes develop mild hypoglycemia. Mutants have impaired mitochondrial function and gluconeogenesis and are hypermetabolic as well as hyperactive. Homozygotes are unable to survive exposure to 4°C for more than 6 hours. Exaggerated startle response, stimulus induced myoclonus, dystonic posturing, and limb clasping are also observed. Transverse aortic constriction (TAC) results in dilated cardiomyopathy and development of heart failure. The Donating Investigator reports that heterozygote X heterozygote crosses yields less than the expected Mendelian ratio (the observed ratio is 1 homozygote in 8); and homozygous mice are more likely to have litters disappear or die after birth. This mutant mouse strain may be useful in studies of metabolic homeostasis, resistance to obesity, hyperactivity and behavior, mitochondrial impairment, neurodegeneration, and heart failure.

Development

A loxP site flanked targeting vector containing hygromycin resistance and thymidine kinase genes utilized in the construction of this mutant. This selection cassette was inserted downstream of exon 5 of the targeted gene, and another loxP site was inserted upstream of exon 3. This construct was electroporated into 129S4/SvJae derived J1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts. The resulting chimeric animals were crossed to C57BL/6 mice. The resulting offspring were then crossed to transgenic mice (on the C57BL/6 genetic background) expressing Cre recombinase under the control of the zona pellucida 3 (Zp3) promoter to remove exons 3 through 5 and the selection cassette. Heterozygotes were crossed to generate homozygotes. The donating investigator reported that the mice were then backcrossed to C57BL/6 (see SNP note below) for 9 generations before arriving at The Jackson Laboratory.

A 32 SNP (single nucleotide polymorphism) panel analysis, with 27 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 rederived living colony at The Jackson Laboratory Repository. While the 27 markers throughout the genome suggested a C57BL/6 genetic background, all 5 markers that determine C57BL/6J from C57BL/6N were found to be segregating, including the rd8 recessive mutation associated with retinal degeneration on Chromosome 1 within the Crb1 locus. These data suggest the mice sent to The Jackson Laboratory Repository were on a C57BL/6N genetic background.

Allele

Symbol: Ppargc1a^tm1Brsp
Name: targeted mutation 1, Bruce M Spiegelman
MGI accession ID: MGI:3511352
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Ppargc1a
Marker name: peroxisome proliferative activated receptor, gamma, coactivator 1 alpha
Chromosome: 5
Strain of origin: 129S4/SvJae
Molecular note: This allele resulted from the crossing of Ppargc1a^tm2Brsp with mice expressing cre recombinase in the germline. Exons 3-5 were removed from the locus. Northern and Western blot analyses indicated a lack of transcript and protein in mutants.