129S/Sv-Ccn2^tm2Mae/J

Stock number: 030767
Product name: Ctgf Lo-Hi
Research areas: Developmental Biology Research, Research Tools

Description

Ctgf Lo-Hi mice allow Cre recombinase-inducible quantitative variation of expression of the Ctgf gene. As part of an allelic set, with the Ctgf KO allele (Stock No. 030769), Ctgf gene expression (transcript) can be altered to range from 30% to 500% of wildtype expression levels. These mice are suitable for use in applications related to the study of development, extracellular matrix homeostasis and fibrosis.

Detailed description

The targeted Ctgf gene encodes a connective tissue mitoattractant/mitogen secreted by vascular endothelial cells, and that is important in extracellular matrix homeostasis, cell adhesion and chondrocyte proliferation and differentiation. These mice carry the Ctgf Lo-Hi allele which allows Cre recombinase-inducible quantitative variation of expression of the Ctgf gene. The endogenous 3' UTR of Ctgf was replaced with a floxed mouse Fos (FBJ osteosarcoma) 3'UTR and bovine GH (growth hormone) 3'UTR. Before exposure to Cre recombinase, the unrecombined hypomorphic allele, Ctgf-Lo, expresses Ctgf using the Fos 3'UTR producing an unstable mRNA. Mice that are homozygous for the unrecombined Ctgf-Lo allele are viable and fertile, and exhibit a Ctgf expression level that is 60% of wildtype. Mice that are heterozygous for the unrecombined Ctgf-Lo allele have a Ctgf expression level that is 85% of wildtype. When these mutant mice are bred to mice that express Cre recombinase, resulting offspring will have the floxed mouse Fos 3'UTR deleted in the cre-expressing tissues - resulting in utilization of the bovine GH 3'UTR which produces a more stable transcript. Mice that are homozygous for the Cre recombined Ctgf-Hi allele exhibit Ctgf expression at a level that is 60% of wildtype. Mice that are heterozygous for the unrecombined Ctgf-Lo allele have a Ctgf expression level that is 85% of wildtype.

When bred to a strain with inducible widespread Cre recombinase expression (see Stock No. 004453 for example), the resulting offspring (after tamoxifen induction) exhibit Ctgf expression (mRNA) levels at approximately 360% of wildtype.

When bred to a strain with Cre recombinase germ line expression (see Stock No. 003724 for example), the resulting offspring (carrying the recombined Ctgf-Hi allele and the Cre recombinase transgene) exhibit an embryonic lethal phenotype (failing to survive past E13.5). Heterozygous embryos at E14.5 of age exhibit craniofacial defects and developmental abnormalities, and express a nine fold increase in Ctgf transcript levels over wildtype controls.

When female mice homozygous for the unrecombined Ctgf-Lo allele are bred to male mice with Cre recombinase germ line expression, a few offspring (4 out of 81), heterozygous for the Ctgf-Hi allele and carrying the Cre recombinase transgene, may survive to adulthood. The surviving Ctgf-Hi heterozygotes exhibit craniofacial and growth defects (small body size, shortened snout, dysmorphic tail, small ears).

Development

A targeting vector containing (3' to 5') a loxP site, the 3' UTR of the Fos (FBJ osteosarcoma) gene, neo cassette, a loxP site, and the 3' UTR of the bovine growth hormone gene was used to disrupt exons 3 through 5 of the Ctgf gene. The construct was electroporated into 129S6/SvEvTac-derived TC1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts. The resulting chimeric animals were tested for germline transmission. The mice were maintained on a 129S6/SvEvTac background. Upon arrival, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize 129S1/SvImJ oocytes (Stock No. 002448).

Allele

Symbol: Ccn2^tm2Mae
Name: targeted mutation 2, Nobuyo Maeda
MGI accession ID: MGI:4838152
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); Hypomorph
Synonyms: Ctgf-Lo
Marker symbol: Ccn2
Marker name: cellular communication network factor 1
Marker synonyms: CTGF; CTGRP; Fisp12; Hcs24; hypertrophic chondrocyte-specific gene product 24; IBP-8; IGFBP8; KMD; NOV2; SEMDLSL
Chromosome: 10
Strain of origin: 129S6/SvEvTac
Molecular note: The endogenous 3' UTR sequence was replaced with a cassette composed of a loxP site followed by the 3' UTR of the Fos gene, followed by the neomycin gene, a second loxP site and finally, the 3' UTR of the bovine growth hormone gene. The modified allele expresses the gene at lower levels whereas, after cre excision of the first 3'UTR and the neo cassette, the endogenous gene is over expressed.