Novel features of dFMR1, the Drosophila orthologue of the fragile X mental retardation protein.

FMRP belongs to a family of widely expressed proteins that contain RNA-binding domains. Although lack of human FMRP results in mental retardation, correlated with subtle synaptic changes, the precise role of FMRP remains elusive. The Drosophila genome contains a single gene homologous to the FXR family. We show that dFMR1 is subjected to transcriptional and posttranscriptional regulation during development and that it homomerizes, like its human counterpart. dFMR1 profile of expression recapitulates that of the human FXR protein family: it is highly enriched in muscles, in central nervous system and in gonads. In the larval brain, anti-dFMR1 also recognizes mushroom bodies, a centre that mediates learning and memory. These features make the fly an ideal system to analyse the role of the FXR family and to identify genes in the FMRP pathway.