PDF neuron firing phase-shifts key circadian activity neurons in Drosophila

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Abstract

Our experiments address two long-standing models for the function of the Drosophila brain circadian network: a dual oscillator model, which emphasizes the primacy of PDF-containing neurons, and a cell-autonomous model for circadian phase adjustment. We identify 5 different circadian (E) neurons that are a major source of rhythmicity and locomotor activity. Brief firing of PDF cells at different times of day generates a phase response curve (PRC), which mimics a light-mediated PRC and requires PDF receptor expression in the 5 E neurons. Firing also resembles light by causing TIM degradation in downstream neurons. Unlike light however, firing-mediated phase-shifting is CRY-independent and exploits the E3 ligase component CUL-3 in the early night to degrade TIM. Our results suggest that PDF neurons integrate light information and then modulate the phase of E cell oscillations and behavioral rhythms. The results also explain how fly brain rhythms persist in constant darkness and without CRY.

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Fang Guo

Howard Hughes Medical Institute, National Center for Behavioral Genomics, Brandeis University, Waltham, United States

Competing interests
The authors declare that no competing interests exist.
Isadora Cerullo

Penn Medicine (University of Pennsylvania Health System), Philadelphia, United States

Competing interests
The authors declare that no competing interests exist.
Xiao Chen

Howard Hughes Medical Institute, National Center for Behavioral Genomics, Brandeis University, Waltham, United States

Competing interests
The authors declare that no competing interests exist.
Michael Rosbash

Howard Hughes Medical Institute, National Center for Behavioral Genomics, Brandeis University, Waltham, United States

For correspondence
rosbash@brandeis.edu

Competing interests
The authors declare that no competing interests exist.

Ethics

Animal experimentation: The research performed in this study on the fruit fly, Drosophila melanogaster, did not require approval by an ethics committee.

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This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.