Figure 1.

Introduction of R255X mutation into Mecp2 affects mRNA and protein expression. (A) Diagrammatic representation of the p.R255X allele. The allele has a single retained loxP sequence within intron 3, the expected nonsense point mutation in exon 4 and no other molecular changes in the locus, confirmed by sequencing. (B) Quantitative PCR of hemibrain lysates reveals that Mecp2^R255X/Y mice brains express Mecp2 mRNA at ∼60% of WT levels. (C) Western blotting shows no full-length or truncated MeCP2 protein produced from the hippocampus or cortex of Mecp2^R255X/Y mice brains. In contrast, brain tissue from Tg1 animals express twice as much MeCP2 as WT, and the addition of Tg1 transgene normalizes MeCP2 protein levels in Mecp2^R255X/Y mice brains. (D) Western blot of human brain lysates from heterozygous female RTT patients who have nonsense mutations in MECP2. No truncation MeCP2 protein product was observed in any of the cases. Lower panel shows levels of GAPDH, which is used as a loading control.