B6.129-Cyp27a1^tm1Elt/J

Stock number: 009106
Product name: cyp27^-
Research areas: Cardiovascular Research, Endocrine Deficiency Research, Internal/Organ Research, Metabolism Research, Research Tools

Description

Cyp27a1^tm1Elt mice (or sterol 27-hydroxylase-deficient mice) harbor a knock-out mutation of the cytochrome P450, family 27, subfamily a, polypeptide 1 locus that abolishes endogenous gene expression. These mice may be useful in studying the conversion of cholesterol to bile acids, as well as lipid and cholesterol homeostasis research.

Detailed description

These mice harbor a targeted mutation of the Cyp27a1 (cytochrome P450, family 27, subfamily a, polypeptide 1) locus that abolishes endogenous gene expression. Homozygous mice (also called Cyp27a1^-/-, cyp27^-/-, or sterol 27-hydroxylase-deficient mice) are viable and fertile, with no RNA or protein expression from the targeted gene detected in liver tissue. Both formation of bile acids and excretion of fecal bile acids are decreased in homozygous mice. Compensatory up-regulation of hepatic enzymes that convert cholesterol to bile acids (bile acid synthesis) is also observed. Cyp27a1^-/- mice exhibit a dramatic increase in cytochrome P450 3A (Cyp3a11) which catalyzes side-chain hydroxylations of bile acid intermediates subsequently facilitating their excretion in the bile and urine. Homozygous mice also have increased expression of other nuclear xenobiotic receptor PXR (pregnane X receptor) target genes.

Development

A targeting vector was designed to replace a 71 bp fragment of the Cyp27a1 (cytochrome P450, family 27, subfamily a, polypeptide 1) locus in exon 8 (upstream to the putative heme-binding site that is crucial for the activity of P-450 enzymes) with a neomycin resistance gene cassette. This construct was electroporated into 129Sv-derived embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts and chimeric mice were bred with C57BL/6J mice to generate the mutant colony. The donating investigator reported that the cyp27-mutant colony was subsequently backcrossed to C57BL/6J inbred mice (see SNP note below) for approximately 12 generations prior to sending to The Jackson Laboratory Repository. Upon arrival, mice were bred to C57BL/6J inbred mice (Stock No. 000664) for at least one generation 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. While the 27 markers throughout the genome suggested a C57BL/6 genetic background, 2 of 5 markers that determine C57BL/6J from C57BL/6N were found to be segregating. These data suggest the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6J ; C57BL/6N genetic background.

Allele

Symbol: Cyp27a1^tm1Elt
Name: targeted mutation 1, Eran Leitersdorf
MGI accession ID: MGI:2181406
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Cyp27a1
Marker name: cytochrome P450, family 27, subfamily a, polypeptide 1
Chromosome: 1
Strain of origin: 129/Sv
Molecular note: A 71 bp fragment of exon 8 was deleted and replaced with a neomycin resistance gene via homologous recombination. The mutant allele was verified by Northern blot analysis of liver extracts from homozygous mutant mice. Western blot analysis of total liver mitochondrial protein from homozygous mutants confirmed the absence of protein product.