In this knockout of the non-coding enhancer element (Rr23or HS746), mRNA expression of Msx1 in mouse embryos is diminished and adult skulls exhibit significant differences in skull morphology. This strain may be useful for downstream analysis of craniofacial development.
Axel Visel, Lawrence Berkeley National Laboratory
The regulatory region 23 (Rr23 or HS746) is a non-coding enhancer element that controls expression of Msx1 (homeobox, msh-like 1), a gene involved in craniofacial development. qPCR analysis indicates a 1.5 fold down regulation of Msx1 in homozygous HS1431 E11.5 and E13.5 embryos. Analysis of the adult skulls from homozygous mice by micro-computed tomography reveals significant differences in skull morphology compared to wild type. Alterations in HS746 include a shortening of the face, a widening of the posterior neurocranium, a narrowing of the palate and shortening of the cranial base. This strain may be useful for downstream analysis of craniofacial development.
A targeting vector containing a loxP-flanked PGKneo cassette was used to delete 1682 bp of the HS746 enhancer sequence. Transient Cre expression in targeted cells excised the neo cassette. The construct was electroporated into 129S6/SvEvTac-derived W4 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts. The resulting chimeric animals were crossed to C57BL/6 mice for approximately three generations. Upon arrival, mice were bred to C57BL/6J for at least 1 generation to establish the colony.
|Allele Name||targeted mutation 1, Axel Visel|
|Allele Type||Targeted (Null/Knockout, No functional change)|
|Gene Symbol and Name||Rr23, regulatory region 23|
|Strain of Origin||129S6/SvEvTac|
|Molecular Note||The enhancer sequence was replaced with a floxed neo selection cassette which was subsequently removed by cre excision.|
While maintaining a live colony, these mice are bred as homozygotes.
When using the B6;129S6-Rr23tm1Axvi/Mmjax mouse strain in a publication, please cite the originating article(s) and include MMRRC stock #36888 in your Materials and Methods section.