B6.129P2-Lipe^tm1Rze/J

Stock number: 019004
Research areas: Diabetes and Obesity Research, Metabolism Research, Reproductive Biology Research, Research Tools

Description

In this HSL-ko strain exons 2 through 7 of the Lipe (lipase, hormone sensitive) gene have been deleted. Homozygotes exhibit accumulation of diglycerides in brown and white fat and have applications in studies of lipid homeostasis and energy metabolism.

Detailed description

Hormone sensitive lipase catalyzes the hydrolysis of diacylglycerol, and of triacylglycerol to a lesser extent, in lipolysis in adipose and non-adipose tissues and is involved in the supply of cholesterol for steroid-hormone production in adrenals and testis. These mice carry a targeted mutation in which exons 2 through 7 have been deleted. Mice that are heterozygous for this targeted mutation are viable and fertile. Although homozygous females are fertile, homozygous males are infertile due to gonadal hypotrophy and oligospermia. No gene product (mRNA or protein) is detected by Northern blot analysis of white adipose tissue, or Western blot analysis of white adipose, cardiac muscle, skeletal muscle, testis, and liver tissues. Homozygotes exhibit decreased white fat cell mass but significant brown fat cell hypertrophy. While triglyceride levels are reduced in cardiac muscle and liver, and elevated in brown adipose tissue; diacylglycerols accumulate in brown fat, white fat, skeletal and cardiac muscle, and testes of homozygotes. After fasting conditions, homozygotes exhibit reduced plasma levels of triacylglycerol and non-esterified fatty acids. Hydrolysis of triglycerides and diacylglycerols is impaired, resulting in decreased free fatty acid and glycerol release from white adipose tissue. Homozygous are partially protected against certain forms of cancer cachexia. Although body weight of female knock out mice is similar to that seen in controls, gonadal white adipose tissue mass is significantly reduced, and decreases progressively with age. Cholesteryl ester hydrolase activity is substantially decreased in brown and white adipose, cardiac and skeletal muscle, liver, kidney, testis, and brain tissue of knock out mice.

Development

A loxP site flanked targeting vector containing NEO HSV-TK selection cassette was utilized in the construction of this mutant. This selection cassette was inserted in intron 1 of the targeted gene, and another loxP site was inserted downstream of exon 7. The construct was electroporated into 129P2/OlaHsd-Hprt^b-m3 derived HM-1 embryonic stem (ES) cells. Correctly targeted ES cells were transiently transfected with a Cre expression plasmid for the purpose of removing the selectable marker cassette. ES cells that had successfully undergone Cre recombination and no longer retained the cassette and the loxP-flanked exons 2-7 were injected in C57BL/6J blastocysts. The resulting chimeric animals were crossed to C57BL/6J mice. The mice were then backcrossed to C57BL/6J for at least 10 generations. Upon arrival at The Jackson Laboratory, the mice were crossed to C57BL/6J (Stock No. 000664) at least once to establish the colony.

Allele

Symbol: Lipe^tm1Rze
Name: targeted mutation 1, Rudolf Zechner
MGI accession ID: MGI:2388334
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Lipe
Marker name: lipase, hormone sensitive
Chromosome: 7
Strain of origin: 129P2/OlaHsd-Hprt1^b-m3
Molecular note: A floxed neomycin selection cassette was inserted in intron 1 and an additional loxP site was inserted 3' to exon 7. The resulting targeted ES cells were subjected to transient cre expression. Exons 2 to 7 as well as neomycin selection cassette were deleted. In addition to this allele, transient expression provided recombinant ES cells in which only the selection cassette was deleted. These cells were used to produce Lipe^tm2Rze.