B6.129P2-Mecp2^tm2Bird/J

Stock number: 006849
Product name: Mecp2^lox-stop
Research areas: Mouse/Human Gene Homologs, Neurobiology Research, Research Tools

Description

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.

Detailed description

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 (Mecp2^lox-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.

Development

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

Symbol: Mecp2^tm2Bird
Name: targeted mutation 2, Adrian Bird
MGI accession ID: MGI:3700191
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); Null/Knockout
Marker symbol: Mecp2
Marker name: methyl CpG binding protein 2
Chromosome: X
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.