B6;129S-Cyp7b1^tm1Rus/J

Stock number: 016108
Research areas: Cardiovascular Research, Cell Biology Research, Metabolism Research

Description

In this strain, a neomycin resistance cassette replaces part of exon 6 of the endogenous Cyp7b1 gene. These mice are useful for studying cholesterol and bile acid metabolism, oxysterol synthesis and breakdown, macrophage function, and B cell trafficking and activation in the immune system.

Detailed description

In this strain, a neomycin resistance (neo) cassette replaces part of exon 6 of the endogenous cytochrome P450, family 7, subfamily b, polypeptide 1 (Cyp7b1) gene, abolishing gene function. Homozygotes are viable and fertile. Cyp7b1 encodes oxysterol 7α-hydroxylase, an enzyme of the alternate bile acid synthesis pathway involved in cholesterol homeostasis. Plasma and tissue levels of 25- and 27-hydroxycholesterol, two oxysterol bioactive lipid substrates of oxysterol 7α-hydroxylase, were elevated in homozygotes. Sterol biosynthetic rates showed a 40% decrease in male kidneys. These mice are useful for studying cholesterol and bile acid metabolism, oxysterol synthesis and breakdown, macrophage function, and B cell trafficking and activation in the immune system.

Development

A targeting vector was designed to replace part of exon 6 encoding the cytochrome P450, family 7, subfamily b, polypeptide 1 (Cyp7b1) gene with a neomycin resistance (neo) cassette. The construct was electroporated into 129/SvEv-derived I1C embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6J blastocysts and the resulting chimeric males were bred to C57BL/6J females. These mice were maintained on a mixed C57BL/6J x 129 background. Upon arrival at The Jackson Laboratory, mice were bred to C57BL/6J (Stock No. 000664) for at least one generation to establish the colony.

Allele

Symbol: Cyp7b1^tm1Rus
Name: targeted mutation 1, David W Russell
MGI accession ID: MGI:2387030
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Cyp7b1
Marker name: cytochrome P450, family 7, subfamily b, polypeptide 1
Chromosome: 3
Strain of origin: 129S/SvEv
Molecular note: The gene was disrupted by replacing the majority of exon 6 (encoding amino acids 410-507) with a neomycin resistance cassette. Homozygous mutant animals lacked enzyme activity as determined by assay of hepatic lysates. Northern blot anlaysis of homozygous animals showed expression of mutant RNA species of larger size compared to wild-type, presumably from abnormal splicing of the gene product. Western blot analysis using polyclonal antibodies recognizing amino acids 266-281 did not detect protein product in liver homogenates from homozygous mutant animals.
General note: ES cell line = I1C.