Hangover Links Nuclear RNA Signaling to cAMP Regulation via the Phosphodiesterase 4d Ortholog dunce

Manuela Ruppert,Mirjam Franz,Anastasios Saratsis,Laura Velo Escarcena,Oliver Hendrich,Li Ming Gooi,Isabell Schwenkert,Ansgar Klebes,Henrike Scholz

doi:10.1016/j.celrep.2016.12.048

Abstract

The hangover gene defines a cellular stress pathway that is required for rapid ethanol tolerance in Drosophila melanogaster. To understand how cellular stress changes neuronal function, we analyzed Hangover function on a cellular and neuronal level. We provide evidence that Hangover acts as a nuclear RNA binding protein and we identified the phosphodiesterase 4d ortholog dunce as a target RNA. We generated a transcript-specific dunce mutant that is impaired not only in ethanol tolerance but also in the cellular stress response. At the neuronal level, Dunce and Hangover are required in the same neuron pair to regulate experience-dependent motor output. Within these neurons, two cyclic AMP (cAMP)-dependent mechanisms balance the degree of tolerance. The balance is achieved by feedback regulation of Hangover and dunce transcript levels. This study provides insight into how nuclear Hangover/RNA signaling is linked to the cytoplasmic regulation of cAMP levels and results in neuronal adaptation and behavioral changes.

Highlights

In mammals and insects alike, repetitive ethanol exposure leads to the development of tolerance (Scholz and Mustard, 2013)
To confirm the role of the PDE4 ortholog Dnc in ethanol tolerance, we investigated the consequence of altered cyclic AMP (cAMP) signaling by analyzing the dnc1 mutant for defects in ethanol-induced behaviors
Hang Function as an RNA Binding Protein To identify the potential mechanism through which Hang regulates rapid ethanol tolerance, we first analyzed the nuclear expression of Hang in the adult brain using an anti-Hang antibody (Figure 1A)

Summary

Introduction

In mammals and insects alike, repetitive ethanol exposure leads to the development of tolerance (Scholz and Mustard, 2013). Tolerance is defined as an increased resistance to the behavioral effects of ethanol upon previous exposure. At least two different mechanisms contribute to the rapid development of tolerance. A Hang-related protein, ZNF699, is associated with alcoholism in humans (Riley et al, 2006), supporting the idea that a cellular stress mechanism underlying ethanol tolerance is evolutionarily conserved between humans and D. melanogaster. Hang mutants develop reduced ethanol tolerance and show defects in their response to oxidative stress and heat shock-induced ethanol resistance. The cellular signaling process upon which Hang acts remains unclear, and how the broadly expressed Hang protein mediates specific behavioral changes in response to global increases of cellular stressors such as ethanol remains an open question

Objectives

Results

Conclusion