Detection of stable RNA transmission across the synapse

Our thoughts and memories are formed by circuits of neurons transmitting information from one to another.

Yet, we have a limited understanding of how long-term symbolic information transfer is achieved in face of the molecular turnover at the synapse.

Recent evidence indicates that ancient retrotransposon elements have been repurposed to transfer genetic information from one cell to another (e.g.

Similarly, circular RNAs (circRNAs), whose formation depend on retrotransposon- derived intronic elements near splice sites, were found to be enriched in the brain.

Although their molecular function remains unknown, I hypothesize that given their resistance to exonucleases (with half-life >60 h) trans-synaptic transfer of circRNA has the potential to transfer information across the synapse on the same time scale as the turnover of several common synaptic receptors.

The current proposal aims to extend an in situ sequencing tool I have already developed to an assay for investigating the transfer of circRNA across the synapse using the Drosophila Neuromuscular Junction (NMJ). We will first establish if circRNAs are transferred from motor neurons across the synapse to muscle cells.

Once specific circRNAs have been identified we will examine their functional role with calcium imaging by using cell-type-specific targeting of Cas13 enzymes to nick the splicing junction only present in the circular version of the transcript in either donor or acceptor cells.