B6N;129S-Acacb^tm1.1Lowl/J

Stock number: 013042
Research areas: Cardiovascular Research, Metabolism Research, Research Tools

Description

The Acc2^flox allele has loxP sites flanking the biotin-binding motif exon (and the preceding exon) of the acetyl-Coenzyme A carboxylase beta (Acacb or Acc2) locus. The exon immediately upstream of the biotin-binding catalytic domain was included so that splicing of the remaining exons following Cre-mediated deletion would introduce a frameshift and nonsense mutation after Asp865 in any translated protein. These mutant mice may be useful to generate conditional mutations for studying malonyl-CoA (the substrate for fatty acid synthesis and the regulator of fatty acid oxidation) synthesis and other metabolic cellular signaling molecules, as well as diet-induced obesity, glucose intolerance and insulin resistance.

Detailed description

Mice homozygous for the Acc2^flox allele are viable, fertile, normal in size, and have no reported physical abnormalities. The Acc2^flox allele has loxP sites flanking the biotin-binding motif exon (and the preceding exon) of the targeted locus. When bred to mice that express Cre recombinase, the resulting offspring will have the floxed sequences deleted in the cre-expressing cells/tissues. The exon immediately upstream of the biotin-binding catalytic domain was included so that splicing of the remaining exons following Cre-mediated deletion would introduce a frameshift and nonsense mutation after Asp865 in any translated protein. These mutant mice may be useful to generate conditional mutations for studying malonyl-CoA (the substrate for fatty acid synthesis and the regulator of fatty acid oxidation) synthesis and other metabolic cellular signaling molecules, as well as diet-induced obesity, glucose intolerance and insulin resistance.

NOTE: When these Acc2^flox mice are bred with germline cre-expressing mice (B6.FVB-Tg(Zp3-cre)3Mrt/J (Stock No. 003394)), the resulting offspring may be bred together to generate Acc2-deficient (Acc2KO) homozygous mice. Such pan Acc2KO homozygotes exhibit reduced total acetyl CoA carboxylase (ACC) activity in skeletal muscle, reduced heart size, decreased cardiac malonyl CoA levels, and a slight increase in energy expenditure (increased oxygen consumption during the dark cycle). Except for the increase in energy expenditure, this pan Acc2KO phenotype is similar to that reported for Acc2-deficient mice lacking exon 12 (Acacb^tm1Dejs; Hoehn et al., 2010 Cell Metab 11:70). However, the pan Acc2KO mice are not reported to display any of the abnormal metabolic effects described for Acacb^tm1Sjw homozygous mice (including reduced fat storage, continuous fatty acid oxidation, improved insulin sensitivity, and protection against obesity and diabetes induced by high-fat/high-carbohydrate diets) (Abu-Elheiga et al., 2001 Science 291:2613). Like the Acc2KO allele, the Acacb^tm1Sjw allele also lacks the biotin-binding domain. Unlike the Acc2KO allele, the Acacb^tm1Sjw allele retains the upstream exon (leaving the mutant RNA in-frame).

Development

A targeting vector was designed to insert a frt-flanked kanamycin cassette and a loxP site downstream of the biotin-binding domain exon, as well as a loxP site upstream of the preceding exon of the Acetyl-CoA carboxylase 2 (Acacb or Acc2) locus. The exon immediately upstream of the catalytic domain was included so that splicing of the remaining exons following Cre-mediated deletion would introduce a frameshift and nonsense mutation after Asp865 in any translated protein. The construct was electroporated into 129S6/SvEvTac-derived W4 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts and chimeric mice were bred with C57BL/6NCrl mice to establish the colony. The mutant mice were then bred to mice expressing Flp recombinase (R26-FLPe on a 129S4 genetic background; see Stock No. 003946) to remove the frt-flanked neo cassette. The resulting Acc2^flox mice had a loxP site upstream of the preceding exon, and a single frt site and second loxP site downstream of the biotin binding domain exon. Acc2^flox mice were maintained on this C57BL/6N;129 mixed genetic background (and the R26-FLPe allele was removed) prior to sending to The Jackson Laboratory Repository. Upon arrival, mice were bred to C57BL/6NJ (Stock No. 005304) for at least one generation to establish the colony.

Allele

Symbol: Acacb^tm1.1Lowl
Name: targeted mutation 1.1, Bradford B Lowell
MGI accession ID: MGI:4450932
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); No functional change
Marker symbol: Acacb
Marker name: acetyl-Coenzyme A carboxylase beta
Chromosome: 5
Strain of origin: 129S6/SvEvTac
Molecular note: LoxP sites were positioned upstream of the preceding exon and downstream of the biotin binding domain exon, with an Frt flanked kanamycin resistance cassette inserted before the 3' loxP site. The Frt-flanked selection cassette was removed by Flpe recombinase-mediated recombination. Splicing of the remaining exons following Cre-mediated deletion would introduce a frameshift and nonsense mutation after Asp865 in any translated protein.