Regulation of Synaptogenesis by the miRNA Pathway and FMR/P Bodies

Post-transcriptional regulation of mRNA is facilitated by different mechanisms, such as microRNA (miRNA) induced gene silencing or fragile X mental retardation protein (FMRP) mediated repression either independent of or acting through cytoplasmic RNA Processing bodies (P bodies). DPTP99A, Lar, and Wg have known functions during synaptogenesis and may be targets of miR-8. Here, we provide evidence that miR-8 regulates DPTP99A in vitro. Non-endogenous miR-8 expressed using an UAS driver regulates Lar. Endogenous miR-8 may regulate DPTP99A in vivo. Here we show that FMRP is capable of colocalizing with the P body components: DCP1, HPat, and Me31B, but not CCR4. We also show that RNAi against HPat and Me31B but not CCR4 and DCP1 are required for FMRP’s repression of a translational reporter in vivo. This functional analysis provides additional insight into another aspect of FMRP’s and P bodies’ ability to cooperatively control repression of mRNA targets.