Abstract：
Mutations in methyl-CpG binding protein 2 (MeCP2), such as the T158M, P152R, R294X, and R306C mutations, are responsible for most Rett syndrome (RTT) cases. These mutations often result in altered protein expression that appears to correlate with changes in the nuclear size; however, the molecular details of these observations are poorly understood. Using a C2C12 cellular system expressing human MeCP2-E1 isoform as well as mouse models expressing these mutations, we show that T158M and P152R result in a decrease in MeCP2 protein, whereas R306C has a milder variation, and R294X resulted in an overall 2.5 to 3 fold increase. We also explored the potential involvement of the MeCP2 PEST domains in the proteasome-mediated regulation of MeCP2. Finally, we used the R294X mutant to gain further insight into the controversial competition between MeCP2 and histone H1 in the chromatin context. Interestingly, in R294X, MeCP2 E1 and E2 isoforms were differently affected, where the E1 isoform contributes to much of the overall protein increase observed, while E2 decreases by half. The modes of MeCP2 regulation, thus, appear to be differently regulated in the two isoforms.
摘要：
甲基-CpG结合蛋白2（MeCP2）的突变，例如T158M，P152R,R294X,和R306C突变，是大多数Rett综合征(RTT)病例的病因。这些突变通常会导致蛋白质表达的改变，这似乎与细胞核大小的变化有关；然而，这些观察的分子细节知之甚少。使用表达人MeCP2-E1亚型的C2C12细胞系统以及表达这些突变的小鼠模型，我们显示T158M和P152R导致MeCP2蛋白减少，而R306C的变异更温和，和R294X导致整体2.5至3倍的增加。我们还探索了MeCP2PEST结构域在蛋白酶体介导的MeCP2调节中的潜在参与。最后,我们使用R294X突变体来进一步了解在染色质背景下MeCP2和组蛋白H1之间有争议的竞争。有趣的是,在R294X中，MeCP2E1和E2亚型受到不同的影响，其中E1同工型有助于观察到的大部分整体蛋白质增加，而E2减少了一半。MeCP2调节的模式，因此，似乎在两种同工型中受到不同的调节。
