Mecp2R168X knock-in mice develop impaired motor function, and behavioral abnormalities such as reduced anxiety. This strain may be useful for in studies of Rett syndrome.
Peter Huppke, University Medical Center Gottingen
The nonsense R168X mutation is one of the most common MeCP2 mutations associated with Rett syndrome (RTT), and produces a truncated mutant protein. These mice carry the R168X knock-in mutation of the Mecp2. An in-frame UGA stop codon is introduced with the adenine at position 502 substituted with thymine in exon 4.
While gene transcript is detected by RT-PCR in total RNA from brain tissue of mutant male mice, no full length or truncated protein is detected in nuclear extracts from brain tissue of hemizygous males. Sequencing confirmed the presence of the mutation.
Hemizygous males are smaller than wildtype littermates and exhibit tremors, hind limb clasping, hypoactivity, irregular breathing, and apnea as early as 27 days of age. Impaired motor performance and decreased anxiety-like behavior of hemizygous males are observed by 6 weeks of age.
Heterozygous females start to develop tremor and hind limb clasping as early as 36 days. By 9 months of age, female heterozygotes exhibit impaired motor control. Mutant mice have poor nest building abilities. Hemizygous males have a median lifespan of 57 days of age, and lifespan range of 23 to 150 days.
A targeting vector containing a FRT site flanked NEO cassette was used to insert the R168X point mutation (502 A to T) into exon 4. The construct was electroporated into 129 derived R1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6 blastocysts. The resulting chimeric males were bred to C57BL/6 females. Heterozygous female mice were were bred to 129S4/SvJaeSor-Gt(ROSA)26Sortm1(FLP1)Dym/J (Stock No. 003946) male mice to remove the FRT site flanked NEO cassette. The mice were then backcrossed to C57BL/6JRj (JANVIER LABS) for 10 generations. Upon arrival at The Jackson Laboratory, the mice were crossed to C57BL/6J inbred mice (Stock No. 000664) at least once to establish the colony.
|Allele Name||targeted mutation 1.1, Peter Huppke|
|Allele Type||Targeted (Humanized sequence)|
|Gene Symbol and Name||Mecp2, methyl CpG binding protein 2|
|Strain of Origin||(129X1/SvJ x 129S1/Sv)F1-Kitl+|
|Molecular Note||A targeting vector containing an FRT flanked neomycin cassette was used to insert an in-frame UGA stop codon in place of the codon (AGA) for arginine (R168X) at position 502 in exon 4. R168X is the most common nonsense mutation associated with Rhett syndrome. Flp-mediated recombination removed the FRT-flanked neo cassette.|
When maintaining a live colony, heterozygous females may be bred with wildtype males from the colony. Median life span for hemizygous males is 57 days of age.
When using the Mecp2R168X knock-in mice mouse strain in a publication, please cite the originating article(s) and include JAX stock #019528 in your Materials and Methods section.