STOCK Gsc^tm2Bhr/J

Stock number: 035392
Product name: Gsc^lacZ
Research areas: Developmental Biology Research, Internal/Organ Research, Research Tools

Description

Gsc^lacZ knock-in/knock-out mice have a beta-galactosidase (lacZ) cassette replacing exon 2 of the endogenous goosecoid homeobox (GSC) gene. Gsc promoter/enhancer sequences direct expression of the beta-galactosidase reporter primarily in craniofacial regions, ventral body wall, and the limbs of developing embryos. These mice may be useful for the study of embryogenesis, development, and craniofacial abnormalities.

Detailed description

The Gsc gene encodes goosecoid, a paired-like homeoprotein which functions like a transcription factor and is involved in gastrulation and skeletal development.

The Gsc^lacZ knock-in/knock-out allele has a lacZ cassette inserted into exon 2 of the Gsc gene. This insertion is expected to create a frameshift mutation, resulting in a null allele. While the absence of full length Gsc protein has not been confirmed for this allele, the donating investigator reports that mice homozygous for the Gsc^lacZ allele are phenotypically identical to other Gsc knock-out mice (such as Stock No. 007556), with perinatal lethality within 24 hours of birth and pronounced craniofacial defects.

Mice heterozygous for the Gsc^lacZ allele are viable and fertile with normal breeding, and have no gross physical or behavioral abnormalities. In heterzygous embryos, lacZ expression can be seen in cranofacial tissues in a pattern consistent with endogenous Gsc expression. Specifically, Gsc-directed β-galactosidase can be observed in the dorsal nasal cartilage, the the lamina propia of the olfactory epithelium, the mesenchymal cells surrounding the external acoustic meatus and the cartilage anlage of the malleus of E15.5 embryos (Rivera-Pérez et al., 1999). The donating investigator indicates that stronger β-galactosidase expression can be observed in homozygous embryos.

Development

The Gsc^lacZ knock-in/knock-out allele was created in the laboratory of Dr. Richard Behringer (MD Anderson Cancer Center). First, a targeting vector was designed to insert a beta-galactosidase (lacZ) reporter cassette and a loxP-flanked neomycin resistance cassette into exon 2 of the goosecoid homeobox locus (Gsc) on chromosome 12. The construct was electroporated into 129S7/SvEvBrd-Hprt⁺ derived AB1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts, and chimeric mice were bred with C57BL/6J for germline transmission. The progeny were subsequently bred to an unspecified germline Cre-expressing strain for removal of the neo cassette. The resulting Gsc^lacZ colony was then backcrossed to C57BL/6J mice for at least 1 generation for removal of the Cre-expressing allele prior to sending males to The Jackson Laboratory Repository in 2021. Upon arrival, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes (Stock No. 000664).

Allele

Symbol: Gsc^tm2Bhr
Name: targeted mutation 2, Richard R Behringer
MGI accession ID: MGI:3716759
Generation method: Targeted
Attributes: Reporter; Null/Knockout
Synonyms: Gsc^lacZ
Marker symbol: Gsc
Marker name: goosecoid homeobox
Marker synonyms: goosecoid; GSC1; SAMS
Chromosome: 12
Strain of origin: Not Specified
Molecular note: An nls-lacZ-SV40pA-floxed neo cassette was inserted into exon 2 then Cre-mediated recombination was used to remove the neo.