Mice with this X-linked lox-STOP mutation of the methyl CpG binding protein 2 gene may be useful in neurological and developmental studies of Rett syndrome and its amelioration upon excision of the lox-STOP cassette.
Adrian Bird, University of Edinburgh
These mice possess a loxP-flanked STOP cassette in intron 2 of the targeted gene on the X chromosome. Western blot and hybridization analysis confirm the absence of wildtype protein from the targeted allele (although the donating investigator reports that the targeted allele produces a "read-through" transcript which does not give rise to detectable levels of protein but makes it difficult to discriminate between the "flox-stopped" and reactivated alleles by RT-PCR). Hemizygous (Mecp2lox-Stop/y) males do not breed and develop Rett syndrome symptoms (reduced mobility, hindlimb clasping) at approximately 6 weeks of age, with death occurring at approximately 11 weeks of age. Heterozygous females are fertile until developing Rett syndrome characteristics at 4-12 months of age. This Rett syndrome-like phenotype is similar to that observed for the traditional knock-out allele (see Stock No. 003890). Cre recombinase-mediated removal of the floxed-STOP cassette restores transcription from the targeted allele and MECP2 protein activity to normal, and reverses the Rett syndrome-like neurological defects.
This mutant mouse strain may be bred to a strain expressing tamoxifen inducible Cre recombinase in most tissues (see Stock No. 004682).
Mice with this X-linked lox-STOP mutation may be useful in neurological and developmental studies of Rett syndrome and its amelioration upon excision of the lox-STOP cassette.
A targeting vector was designed to insert a loxP-flanked STOP-Neo cassette into intron 2 of the targeted gene. The STOP-Neo cassette is composed of a PGK-Neo cassette followed by the 3' portion of the yeast His3 gene, an SV40 polyadenylation sequence, and a false translation initiation codon followed by a 5' splice donor site. The construct was electroporated into 129P2/OlaHsd-derived E14TG2a embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6 blastocysts, and chimeric offspring were bred to C57BL/6 mice. Heterozygous female mutants were bred to wild-type C57BL/6 males for 5 generations prior to arrival at The Jackson Laboratory. A SNP (single nucleotide polymorphism) panel analysis performed in April 2009 by The Jackson Laboratory revealed that this strain was on a mixed B6;129 genetic background background. Further backcrossing to C57BL/6J inbred mice generated mutant mice congenic on a C57BL/6 genetic background (confirmed by SNP analysis August 2009).
|Allele Name||targeted mutation 2, Adrian Bird|
|Allele Type||Targeted (Conditional ready (e.g. floxed), Null/Knockout)|
|Allele Synonym(s)||Mecp2lox-stop; Mecp2stop|
|Gene Symbol and Name||Mecp2, methyl CpG binding protein 2|
|Strain of Origin||129P2/OlaHsd|
|Molecular Note||Cre recombinase-reversible gene inactivation was accomplished by insertion into intron 2 of a 3.1-kb DNA fragment containing a loxP-flanked "neostop" cassette, which comprises a neomycin resistance cassette followed by a transcriptional/translational "stop" cassette composed of 550 bp of 3' sequence from the Saccharomyces cerevisiae His3 gene, an SV40 polyadenylation sequence, and a synthetic sequence containing a false translation initiation codon (ATG) immediately followed by a consensus splice donor sequence. Despite the production of a read-through transcript, no protein product was detected by western blot or immunofluorescence analysis of brains of mutant mice.|
|Mutations Made By|| |
Adrian Bird, University of Edinburgh
When maintaining a live colony, females heterozygous for this X-linked mutation can be bred with wildtype male siblings. The donating investigator recommends replacing heterozygous female breeders when Rett syndrome symptoms appear or when females fail to produce or care for regular litters (may be as early as 4-6 months). The donating investigator also reports that breeding performance may be improved if mice are maintained on a mixed C57BL/6;BALB/c background.
When using the Mecp2lox-stop mouse strain in a publication, please cite the originating article(s) and include JAX stock #006849 in your Materials and Methods section.