# Neural development goes retro: Gags as essential modulators of synapse formation

## TL;DR

A retrotransposon's gag protein helps control synapse formation in fruit fly nerve connections.

## Contribution

The study identifies Copia's gag protein as a modulator of synapse formation through RNA transfer.

## Key findings

- Copia's gag protein forms virus-like capsids that transfer RNA across neuromuscular junctions.
- Copia's gag protein regulates synapse formation in Drosophila.
- Copia and Arc, both retrotransposon gag proteins, act antagonistically in synapse regulation.

## Abstract

Neurodevelopment requires dynamic control of synapse number. A new study in PLOS Biology reveals that the gag protein of Copia, an active retrotransposon, forms virus-like capsids that transfer its own RNA across the Drosophila neuromuscular junction. Here, Copia acts antagonistically with Arc, another retrotransposon gag protein, to regulate synapse formation.

Neurodevelopment requires dynamic control of synapse number. This Primer highlights a new study in PLOS Biology which reveals that the gag protein of Copia, an active retrotransposon, forms virus-like capsids that transfer its own RNA across the Drosophila neuromuscular junction, to regulate synapse formation.