Lisa A. Gabel, Sandra Won, Hideki Kawai, Margaret McKinney, Alan M. Tartakoff, and Justin R Fallon
The most common form of inherited mental retardation, Fragile X syndrome (FXS), results from triplet repeat expansion in Fmr1 gene, leading to loss of Fragile X mental retardation protein(FMRP) expression. Normally, FMRP binds to and represses translation of mRNA's, including those expressed in dendrites and near synapses. In this issue, Gabel et al. report that FMRP expression is dynamically regulated in vivo in dark-reared, light-exposed rats. Interestingly, the regulation was posttranscriptional, because FMRP and mRNA levels remained constant, suggesting that the increased levels might be attributable to altered degradation of FMRP.