B6;129S-Ldlr^tm1Her Apob^tm2Sgy/J

Stock number: 003000
Product name: apo-B¹⁰⁰
Research areas: Cardiovascular Research, Developmental Biology Research, Metabolism Research, Mouse/Human Gene Homologs, Neurobiology Research

Description

These double mutant mice express only the apo-B100 isoform and a truncated nonfunctional (unable to bind LDL) low density lipoprotein receptor. These mice may be suitable for use in studies related to cholesterol and lipid metabolism.

See Updated Apob Allele Information below [2020].

Detailed description

This strain expresses only APO-B100 (normally expressed in the liver and yolk sac) and is deficient in low density lipoprotein receptor (Ldlr^tm1Her/Ldlr^tm1Her). No ApoB48 isoform is detected by western blot analysis of plasma lipoproteins from homozygotes. Mice that are homozygous for both alleles are viable and fertile.

Updated Apob Allele Information: In 2020, analysis by The Jackson Laboratory determined the mice to have the post-FIAU Apo-B¹⁰⁰ (the neo, TK and duplicate exons 26-29 deleted) allele on one homologous chromosome, and pre-FIAU Apo-B¹⁰⁰ (retaining the neo, TK and duplicate exons 26-29) on the other homologous chromosome. This analysis also confirmed that RT-PCR of compound heterozygous liver shows predicted change in coding component (CAA to CTA in codon 2179), and reduced HDL was verified (64.2 mg/dL +/- 9.02 [n=9] compared to C57BL/6J 94.9 mg/dL +/-6.5 [n=4]).

Development

A "hit and run"-type vector was used to create a CTA to TTA mutation in codon 2179 (codon 2153 in the original publication) sequences corresponding to the apo-B48 editing codon in exon 26 of the mouse Apob gene. The mutation was created through homologous recombination in 129S7/SvEvBrd-Hprt⁺-derived embryonic stem (ES) cells. Western blot analysis on plasma derived from heterozygous and homozygous mice demonstrates that the expression of the ApoB100 isoform is unaffected by this mutation, while no ApoB48 isoform is produced from this allele.
The original publication (Farese et al. 1996 Proc Natl Acad Sci U S A. 93:6393 [PMID:8692825]) indicates in vitro treatment with 1-[2-fluoro-13-D-arabinofuranosyl]-5-iodouracil (Fialuridine [FIAU]) was performed in an effort to delete the 3' targeting vector sequences (neo, thymidine kinase, and duplicate exons 26-29) - see Updated Apob Allele Information below.
Updated Apob Allele Information: In 2020, analysis by The Jackson Laboratory determined the mice to have the post-FIAU Apo-B¹⁰⁰ (the neo, TK and duplicate exons 26-29 deleted) allele on one homologous chromosome, and pre-FIAU Apo-B¹⁰⁰ (retaining the neo, TK and duplicate exons 26-29) on the other homologous chromosome. This analysis also confirmed that RT-PCR of compound heterozygous liver shows predicted change in coding component (CAA to CTA in codon 2179), and reduced HDL was verified (64.2 mg/dL +/- 9.02 [n=9] compared to C57BL/6J 94.9 mg/dL +/-6.5 [n=4]).

For the Ldlr^tm1Her allele, a targeting vector containing a NEO selection cassette was used to disrupt exon 4 of the targeted Ldlr gene. The construct was electroporated into 129S7/SvEvBrd-Hprt⁺ derived AB1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6 blastocysts. The resulting chimeric animals were bred to C57BL/6 to achieve germline transmission.

Mice carrying the targeted mutations were bred together to generate these double mutant mice as Stock No. 003000.

Allele

Symbol: Apob^tm2Sgy
Name: targeted mutation 2, Stephen G Young
MGI accession ID: MGI:1857304
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Apob
Marker name: apolipoprotein B
Chromosome: 12
Strain of origin: 129S7/SvEvBrd-Hprt⁺
Site of expression: Expression of the ApoB100 isoform is unaffected by this mutation, while no ApoB48 isoform, which is normally synthesized by the small intestine, is produced from this allele.
Molecular note: A "hit and run"-type vector was used to create a CTA to TTA mutation in codon 2179 (codon 2153 in the original publication) in sequences corresponding to the apo-B48 editing codon. Western blot analysis on plasma derived from heterozygous and homozygous mice demostrated that the expression of the ApoB100 isoform is unaffected by this mutation, while no ApoB48 isoform is produced from this allele.
General note: Levels of LDL-cholesterol, VLDL, and triglyceride LDL are higher relative to wild-type mice in APOB100 only mice in the presence of wild-type APOE production. In the presence of genetic APOE deficiency, APOB100 only mice have lowered cholesterol levels (J:33830).

Phenotypic Similarity to Human Syndrome: Calcific Aortic Valve Disease J:227165 in mice homozygous for Apob^tm2Sgy and Ldlr^tm1Her and carrying the Tg(Ins-Igf2)1Fbos transgene.

Allele

Symbol: Ldlr^tm1Her
Name: targeted mutation 1, Joachim Herz
MGI accession ID: MGI:1857212
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Ldlr
Marker name: low density lipoprotein receptor
Chromosome: 9
Strain of origin: 129S7/SvEvBrd-Hprt⁺
Site of expression: Immunoblot analysis of liver membranes detected a truncated protein in homozygous mutant animals.
Molecular note: Insertion of a neomycin resistance cassette into exon 4. The authors predict that the targeted allele would encode a truncated non-functional protein that will not bind LDL, and that lacks a membrane spanning segment. Immunoblot analysis of liver membranes detected a truncated protein in homozygous mutant animals.
General note: When used in bone marrow transplant into Ldlr^tm1Her homozygous mice, Abca1^tm1Jdm Abcg1^tm1Dgen homozygous cells accelerate the development of atherosclerosis. (J:130777)

Phenotypic Similarity to Human Syndrome: Atherosclerosis, Susceptibility to J:29950, J:225091 in mice fed a high-cholesterol diet.