Hippocampal neurons, nylon-2 experiments

Ongoing neuronal activity during development and plasticity acts to refine synaptic connections and contributes to the induction of plasticity and ultimately long term memory storage. Activity-dependent post-transcriptional control of mRNAs occurs through transport to axonal and dendritic compartments, local translation, and mRNA stability. We have identified a mechanism that contributes to activity-dependent regulation of mRNA stability during synaptic plasticity. In this study we demonstrate rapid, post-transtriptional control over process-enriched mRNAs by neuronal activity. Systematic analysis of the 3'-UTRs of destablized transcripts, identifies enrichment in sequence motifs corresponding to miRNA binding sites. The miRNAs that were identified, miR-326-3p/miR-330-5p, miR-485-5p, miR-666-3p, and miR-761 are predicted to regulate networks of genes important in plasticity and development. We find that these miRNAs are developmentally regulated in the hippocampus, many increasing by postnatal day 14. We further show that miR-485-5p controls NGF-induced neurite outgrowth in PC12 cells, tau expression, and axonal development in hippocampal neurons. miRNAs can function at the synapse to rapidly control and affect short- and long-term changes at the synapse. These processes likely occur during refinement of synaptic connections and contribute to the induction of plasticity and learning and memory. 12 hippocampal cell culture samples analysed, 3 coverslips pooled per sample. Treatments are as follows: Block: an inhibitor cocktail containing 50 µM D-APV, 40 µM CNQX, and 100 nM TTX for 3 hrs Activity: 50 µM bicuculline (BiC)/500 µM 4-Aminopyridine ActD: 25 µM actinomycin D