B6;129P2-Pnpla2^tm1Rze/J

Stock number: 019003
Product name: ATGL-ko
Research areas: Cardiovascular Research, Developmental Biology Research, Diabetes and Obesity Research, Internal/Organ Research, Metabolism Research, Neurobiology Research, Research Tools

Description

In this ATGL-ko strain a NEO cassette replaces exon 1 of the Pnpla2 (patatin-like phospholipase domain containing 2) gene. Homozygotes exhibit a shortened lifespan, abnormal lipid homeostasis, glucose tolerance, and cardiovascular physiology and have applications in studies of impaired cardiac function, thermogenesis and lipid and energy homeostasis.

Detailed description

Patatin-like phospholipase domain containing 2 (PNPLA2, ATGL) initiates lipolysis by catalyzing the hydrolysis of triacylglycerol to diacylglycerol in adipose tissue and non-adipose tissues. Mutations in human PNPLA2 have been associated with neutral lipids storage disorder with myopathy. These mice carry a targeted mutation of the Pnpla2 gene in which exon 1 (encoding the translational initiation codon and the lipase consensus sequence motif,) is replaced by a NEO cassette. Mice that are heterozygous for the targeted mutation are viable and fertile. Homozygotes die at about 14 to 16 weeks of age due to severe cardiac steatosis and lethal myopathy. Triacylglycerol hydrolase activity in homozygotes is decreased by more than 80% in white and brown adipose tissue, and reduced in cardiac muscle, skeletal muscle, testis, and in the liver. Levels of plasma free fatty acids are reduced in both fed and fasting homozygotes. Mice homozygous for this targeted mutation have 2 fold increased body mass, as well as increased gonadal and inguinal white adipose tissue. Intrascapular brown adipose tissue is increased more than 10-fold when compared to wildtype controls. Homozygotes exhibit increased levels of triacylglycerol also in most non-adipose tissues with a more than 10-fold increase in cardiac muscle. Following an overnight fast, homozygotes are hypoinsulinemic (ciruculating insulin levels reduced by 70%) and hypoglycemic (reduced approximately 40%). Fed homozygous mice exhibit a 40% reduction in circulating insulin compared to levels seen in controls. Homozygotes exhibit increased glucose tolerance and increased respiratory quotient during fasting. Homozygotes are sensitive to cold temperatures, experiencing severe hypothermia after 5 hours in 4 degrees celcius. Homozygous are protected against certain forms of cancer cachexia.

Development

A targeting vector containing a NEO cassette was used to disrupt exon 1, which encodes the translational initiation codon and the lipase consensus sequence motif (GXSXG). The construct was electroporated into 129P2/OlaHsd-Hprt^b-m3 derived HM-1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6J blastocysts. The resulting chimeric animals were crossed to C57BL/6J mice. The donating investigator reported that these mice were backcrossed to C57BL/6J for at least 10 generations (see SNP note below). Upon arrival at The Jackson Laboratory, the mice were crossed to C57BL/6J (Stock No. 000664) at least once to establish the colony.

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. Three markers throughout the genome were segregating for 129, suggesting an incomplete backcross.

Allele

Symbol: Pnpla2^tm1Rze
Name: targeted mutation 1, Rudolf Zechner
MGI accession ID: MGI:3629035
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Pnpla2
Marker name: patatin-like phospholipase domain containing 2
Chromosome: 7
Strain of origin: 129P2/OlaHsd-Hprt1^b-m3
Molecular note: A neomycin resistance cassette replaced the first exon including the translational start codon and the lipase consensus sequence motif (GXSXG). Northern analysis of white adipose tissue did not detect transcript in white adipose tissue from homozygous mutant mice. Similarly, western blot analysis of white adipose tissue from homozygous mutant mice did not detect protein.