FVB.129X1(B6)-Tfr2^tm1Slu/J

Stock number: 005215
Research areas: Hematological Research, Immunology, Inflammation and Autoimmunity Research, Internal/Organ Research, Metabolism Research, Mouse/Human Gene Homologs

Description

These Tfr2^Y245X mutant mice have codon 245 of the targeted gene converted to a stop codon; this mutation corresponds to the human truncation mutation Y250X which is the cause of hemochromatosis (HH type 3). As such, these Tfr2^Y245X mutant mice may be useful in studying intestinal iron loading and hemochromatosis type 3.

Detailed description

These Tfr2^Y245X mice have codon 245 of the targeted gene converted to a stop codon; this mutation corresponds to the human truncation mutation Y250X which is the cause of hemochromatosis (HH type 3). Mice that are homozygous for the targeted mutation are viable and fertile. Northern blot analysis of total RNA from liver tissue detects a reduced level of full length gene product (mRNA). PCR analysis of liver tissue detects the C to G point mutation in exon 6. Western blot analysis of hepatic membrane preparations does not detect truncated gene product (protein). By 4 weeks of age, homozygotes display ~5-fold increase in liver iron levels and ~1.5-fold increase in serum transferrin saturations levels over wildtype control. Iron deposition in the liver is hepatocellular and periportal. Mice homozygous for the mutation have decreased iron concentrations in the spleen, indicating reticuloendothelial iron sparing. These Tfr2^Y245X mutant mice may be useful in studying intestinal iron loading and hemochromatosis type 3.

In an attempt to offer alleles on well-characterized or multiple genetic backgrounds, alleles are frequently moved to a genetic background different from that on which an allele was first characterized. It should be noted that the phenotype could vary from that originally described. We will modify the strain description if necessary as published results become available.

Development

A targeting vector was designed to disrupt exon 6 and intron 6 of the targeted gene with a C to G point mutation at codon 245 (Y245X) in exon 6 and a loxP site flanked self-deleting selection cassette (containing a neomycin resistance gene and Cre recombinase under the control of a testes-specific angiotensin-converting enzyme promoter). The construct was electroporated into 129X1/SvJ derived RW4 embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts, and chimeric males were crossed to C57BL/6J females. The resulting mutant offspring (with the selection cassette excised following cre expression in the germ line of the chimeric males) were established. The Tfr2^Y245X mutant strain was maintained on this mixed genetic background for many generations. Subsequently, these Tfr2^Y245X mutant mice were backcrossed to FVB/N inbred mice for at least 10 generations prior to arrival at The Jackson Laboratory. Upon arrival, mutant mice were bred with FVB/NJ inbred mice (Stock No. 001800) for at least one generation to establish the colony.

Allele

Symbol: Tfr2^tm1Slu
Name: targeted mutation 1, St Louis School of Medicine
MGI accession ID: MGI:2384726
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Tfr2
Marker name: transferrin receptor 2
Chromosome: 5
Strain of origin: 129X1/SvJ
Molecular note: A construct containing a nonsense mutation at codon 245 (in exon 6 and orthologous to human position 250) and a floxed neo cassette in intron 6 was incorporated at the endogenous locus via homologous recombination. Transient transfection of ES cells with cre excised the neo cassette, leaving a single loxP site. Northern blot analysis of total hepatic RNA showed a reduced abundance of normal size transcript in homozygous mutant mice, putatively due to nonsense-mediated decay. Encoded protein was undetected by Western blot analysis.