C57BL/6J-Ldlr^Hlb301/J

Stock number: 005061
Product name: WHC
Strain synonyms: HLB301
Research areas: Cardiovascular Research, Internal/Organ Research, Mouse/Human Gene Homologs

Description

The single point mutation (Ldlr^Hlb301) in this ENU mutagenized strain was originally named "Wicked High Cholesterol" (WHC) for a phenotype of elevated atherosclerotic lesion formations and reduced hepatosteatosis following an atherogenic diet. This mutant mouse strain may be useful in studies of familial hypercholesterolemia and atherosclerosis.

Detailed description

Mice that are homozygous for the mutation are viable, fertile, normal in size and do not display any gross physical or behavioral abnormalities. This single base pair G to A transition mutation in exon 14, nucleotide 2096 was induced by ENU mutagenesis. The "Wicked High Cholesterol" (WHC) phenotype was mapped to the Ldlr, low density lipoprotein receptor, gene. Although total plasma cholesterol levels do not differ between sexes, when fed a standard chow diet for 5 weeks, homozygous WHC males exhibit higher triglyceride and HDL levels than homozygous WHC females. When fed Western diet for 5 weeks, mutant WHC males exhibit higher HDL levels than female WHC mutants. When fed an atherogenic diet for 5 weeks, WHC homozygotes of both sexes develop elevated total cholesterol levels of more than a 4 fold increase when compared to WHC homozygotes on standard chow diet. Cholesterol and HDL levels of WHC homozygotes fed atherogenic diet for 5 weeks remain elevated 1 month after resuming chow diet. Atherosclerotic lesions develop in WHC homozygotes fed Western and atherogenic diet, with the largest lesions observed in homozygous WHC mice fed the atherogenic diet. Long term (34 weeks) atherogenic diet consumption results in formation of multiple cutaneous xanthomas in the distal limbs of WHC homozygotes, 42 weeks of age. Half of the WHC homozygotes develop gallstones.

On the atherogenic diet WHC homozygotes develop significantly greater HDL and triglyceride levels, as well as larger atherosclerotic lesions, when compared to mice carrying the Ldlr targeted mutation (Stock No. 002207).

This mutant mouse strain may be useful in studies of familial hypercholesterolemia and atherosclerosis.

Development

Following multidose ethylnitrosourea (ENU) treatments to induce mutations in male founder C57BL/6J mice (Stock No. 000664), a forward genetic screen was utilized to identify phenotypic deviants in complex heart, lung, blood, and sleep disorders, at the Mouse Heart, Lung, Blood, and Sleep Disorders (HLBS) Center at The Jackson Laboratory. Screening of third generation mice (G3) identified mice with elevated total plasma cholesterol levels after being fed an atherogenic diet for 5 weeks. The "Wicked High Cholesterol" (WHC) phenotype was mapped to chromosome 9. Sequencing of the candidate gene Ldlr, low density lipoprotein receptor, revealed a G to A transition in exon 14, nucleotide 2096; missense mutation C699Y. Heterozygotes were crossed to generate homozygotes. The mice have been maintained on a C57BL/6J background.

Allele

Symbol: Ldlr^Hlb301
Name: heart, lung and blood 301
MGI accession ID: MGI:2683091
Generation method: Chemically induced (ENU)
Marker symbol: Ldlr
Marker name: low density lipoprotein receptor
Chromosome: 9
Strain of origin: C57BL/6J
Molecular note: This phenotypic mutation was identified in a screen of the progeny of ENU treated male mice for serum cholesterol elevation in response to a high fat, high cholesterol diet. It is a G to A transition at nucleotide 2096 of the mouse cDNA sequence, in a region encoded by exon 14, resulting in replacement of a highly conserved cysteine by tyrosine at amino acid 699 (C699Y; count includes 21-aa signal peptide), which is predicted to cause a folding defect and failure of the protein to transit from the endoplasmic reticulum to the Golgi system.
General note: Schmidt and Kostner (Atherosclerosis 148(2):431-432, 1999) identified the same mutation in an Austrian patient with Familial Hypercholesterolemia (FH): a G-to-A transition at nucleotide 2093 of the human LDLR coding sequence, resulting in replacement of cysteine with tyrosine at amino acid 677 (count does not include 21-aa signal peptide).