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Circadian rhythms in neuronal activity propagate through output circuits

Nature Neuroscience volume 19, pages 587595 (2016) | Download Citation

Abstract

Twenty-four hour rhythms in behavior are organized by a network of circadian pacemaker neurons. Rhythmic activity in this network is generated by intrinsic rhythms in clock neuron physiology and communication between clock neurons. However, it is poorly understood how the activity of a small number of pacemaker neurons is translated into rhythmic behavior of the whole animal. To understand this, we screened for signals that could identify circadian output circuits in Drosophila melanogaster. We found that leucokinin neuropeptide (LK) and its receptor (LK-R) were required for normal behavioral rhythms. This LK/LK-R circuit connects pacemaker neurons to brain areas that regulate locomotor activity and sleep. Our experiments revealed that pacemaker neurons impose rhythmic activity and excitability on LK- and LK-R-expressing neurons. We also found pacemaker neuron–dependent activity rhythms in a second circadian output pathway controlled by DH44 neuropeptide–expressing neurons. We conclude that rhythmic clock neuron activity propagates to multiple downstream circuits to orchestrate behavioral rhythms.

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Acknowledgements

We thank B. Al-Anzi (California Institute of Technology), D. Clark (Yale University), P. Hardin (Texas A & M University), P. Herrero (Universidad Autónoma de Madrid), M. Rosbash (Brandeis University), F. Rouyer (Institut des Neurosciences Paris-Saclay), A. Sehgal (University of Pennsylvania School of Medicine), O. Shafer (University of Michigan), S. Sweeney (University of York), the Developmental Studies Hybridoma Bank and the Bloomington stock center for flies and antibodies. We thank the TRiP stock center at Harvard Medical School (NIH/NIGMS R01-GM084947) for transgenic RNAi fly stocks. We thank C. Desplan for sharing the two-photon microscope and perfusion chamber and O. Shafer for advice on calcium imaging. We thank R. Behnia, C. Desplan, C. Hackley, E. Meekhof, A. Petsakou, H. Piggins and Z. Zhu for discussions and comments on the manuscript. This investigation was conducted in facilities constructed with support from Research Facilities Improvement Grant Number C06 RR-15518-01 from the National Center for Research Resources, US National Institutes of Health (NIH). Imaging was performed at the NYU Center for Genomics & Systems Biology. This work was supported by EMBO ALTF 249-2009 (M.C.), the Charles H. Revson foundation (M.C.), EMBO ALTF 680-2009 (C.B.), HSFPO LT000077/2010-l (C.B.), NIH grant R01 EY017916 (to C. Desplan), NIH grant GM063911 (J.B.) and the NYU Abu Dhabi Research Institute (G1205).

Author information

Author notes

    • Matthieu Cavey
    •  & Claire Bertet

    Present address: Aix-Marseille Université, CNRS, IBDM UMR7288, Marseille, France.

    • Ben Collins

    Present address: Institute of Pharmacology and Toxicology, University of Zürich, Zürich, Switzerland.

Affiliations

  1. Department of Biology, New York University, New York, New York, USA.

    • Matthieu Cavey
    • , Ben Collins
    • , Claire Bertet
    •  & Justin Blau
  2. Center for Genomics & Systems Biology, New York University Abu Dhabi Institute, Abu Dhabi, United Arab Emirates.

    • Matthieu Cavey
    •  & Justin Blau
  3. Program in Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates.

    • Justin Blau

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Contributions

M.C. and B.C. performed the RNAi screen. M.C. performed all other experiments and analyses except the immunostaining in Supplementary Figure 3, which was done by C.B. M.C. and J.B. wrote the manuscript, with comments from B.C. and C.B.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Justin Blau.

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DOI

https://doi.org/10.1038/nn.4263

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