B6.129-Dio2^tm1Vag/J

Stock number: 018985
Product name: D2KO
Strain synonyms: Dio2^-
Research areas: Endocrine Deficiency Research, Internal/Organ Research, Metabolism Research

Description

These Dio2 knockout mice may be useful in applications involving thyroid hormone homeostasis, metabolism regulation, and bone strength.

Detailed description

A neo cassette replaces sequence including the 5' end of exon 2 of the deiodinase, iodothyronine, type 2 (Dio2) gene. The replaced sequence includes the TGA selenocysteine codon, removal of which abolishes gene function in these D2KO mice. D2 is a selenoenzyme expressed mainly in the pituitary, brown adipose tissue (BAT) and brain where it generates local triiodothyronine (T₃) thyroid hormone. Homozygotes are viable and fertile. D2KO mice exhibit deficits in thyroid stimulating hormone (TSH) regulation, thermogenesis, and auditory function. Brain T₃ content is reduced while brain thyroxine (T₄) content is elevated. The bones of D2KO mice are more brittle and fracture easier. They show a reduction in bone formation and an increase in skeletal mineralization.

Development

A targeting vector was designed to replace sequence, including the 5' end of exon 2, of the deiodinase, iodothyronine, type 2 (Dio2) gene with a neomycin resistance (neo) cassette. The construct was electroporated into 129S7/SvEvBrd-Hprt^b-m2-dervived AB2.2 embryonic stem (ES) cells and correctly targeted ES cells were injected into C57BL/6 blastocysts. The resulting chimeric males were bred to C57BL/6 females and subsequently a colony of D2KO mice were established. D2KO mice were then mated to D1KO mice deficient of the deiodinase, iodothyronine, type I (Dio1) gene. These double mutant mice were backcrossed for at least 10 generations to C57BL/6 mice. Upon arrival at The Jackson Laboratory, mice were bred to C57BL/6J (Stock No. 000664) for at least one generation and the D1KO and D2KO alleles were separated. D1KO mice are maintained a Stock No. 018984.

Allele

Symbol: Dio2^tm1Vag
Name: targeted mutation 1, Valerie Anne Galton
MGI accession ID: MGI:2182450
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Dio2
Marker name: deiodinase, iodothyronine, type II
Chromosome: 12
Strain of origin: 129S7/SvEvBrd-Hprt^b-m2
Molecular note: A neomycin selection cassette replaced a 2.6kb region including a 5' portion of exon 2. 72% of the coding region was deleted, including a TGA codon that encodes the selenocysteine located at the active site. Northern blot analysis of total RNA obtained from brown adipose tissue showed an absence of transcript in homozygous mutant mice. Functional ablation of the endogenous protein in homozygous mutant mice was confirmed by assaying deiodination in brown adipose tissue.