This targeted mutation of the sonic hedgehog (Shh) gene displays growth abnormalities including small size, reduced brain weight, decreased cell proliferation, hypoplasia in the olfactory bulb and cerebellum and may be useful in studies of cell proliferation and SHH signaling.
Rosalind A Segal, Dana Farber Cancer Institute
Mice that are homozygous for the targeted mutation are viable, fertile and do not exhibit patterning defects found in Shh null mutants. The R34A and K38A mutations are targeted to the conserved Cardin Weintraub motif and reduce SHH high-affinity proteoglycan binding. Homozygous mice exhibit reduced body weight, small eyes, hypoplasia of the cerebellum and olfactory bulb, reduced precursor cell proliferation in the cerebellar granule cell layer, the spinal cord, the subventricular zone and the hippocampal subgranular layer. This mutant mouse strain may be useful in studies of cell proliferation and SHH-signaling.
A targeting vector containing the amino acid substitutions Arg33Ala and Lys37Ala was used to disrupt exon 1 and a loxP-flanked PGKneo cassette was inserted in the intron between exon 1 and 2. The construct was electroporated into 129S4/SvJae-derived J1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts. The neomycin cassette was removed by transient transfection with a Cre recombinase expressing plasmid leaving a single loxP site downstream of exon 1. The resulting chimeric animals were crossed to C57BL/6 mice for two generations. Upon arrival, mice were bred to C57BL/6J for at least 1 generation to establish the colony.
|Allele Name||targeted mutation 1.1, Rosalind A Segal|
|Gene Symbol and Name||Shh, sonic hedgehog|
|Promoter||Shh, sonic hedgehog, mouse, laboratory|
|Strain of Origin||129S4/SvJae|
|Molecular Note||Mutations (R34A/K38A) were introduced into the N-terminal Cardin-Weintraub motif encode by exon 1 to reduce high-affinity Shh-proteoglycan interaction without altering Shh's affinity for its receptor. For targeting purposes, a floxed neomycin cassette was introduced into intron 1 and subsequently removed by transient expression of cre recombinase. Expression levels of the mutant protein in homozygotes was identical to wild-type as determined by immunoblot analysis of cerebella extracts.|
|Mutations Made By|| |
Rosalind Segal, Dana Farber Cancer Institute
While maintaining a live colony, these mice are bred as homozygotes.
When using the B6;129S4-Shhtm1.1Rseg/J mouse strain in a publication, please cite the originating article(s) and include JAX stock #011031 in your Materials and Methods section.