Abstract
Summary Long term synaptic plasticity requires transcription in response to changes in neuronal activity. While genes induced by neuronal activity have been extensively studied, genes induced by hyperpolarization are largely unknown. We focused on Pura , a Rho1 GEF whose rhythmic expression drives the daily retraction of the projections of Drosophila LN v circadian pacemaker neurons. We found that Pura transcription is repressed by activity and induced by hyperpolarization in LN v s – the opposite of typical activity-regulated genes. Pura is repressed by activity-regulated transcriptional factors including Mef2 and Sr (fly Egr-1) and activated by Toy, a Pax6 transcription factor. toy transcription is also induced by inactivity. Thus toy and Pura represent a class of genes induced by hyperpolarization. Highlights Hyperpolarization activates transcription of Pura , a plasticity gene This phenomenon occurs in circadian pacemaker neurons and mushroom body neurons The Pura enhancer integrates recent neuronal activity to regulate transcription Hyperpolarization activates transcription of toy (Pax-6), which then activates Pura