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Conserved properties of Drosophila Insomniac link sleep regulation and synaptic function
Journal article   Open access   Peer reviewed

Conserved properties of Drosophila Insomniac link sleep regulation and synaptic function

Qiuling Li, David A Kellner, Hayden A M Hatch, Tomohiro Yumita, Sandrine Sanchez, Robert P Machold, C Andrew Frank and Nicholas Stavropoulos
PLoS genetics, Vol.13(5), pp.e1006815-e1006815
05/2017
DOI: 10.1371/journal.pgen.1006815
PMCID: PMC5469494
PMID: 28558011
url
https://doi.org/10.1371/journal.pgen.1006815View
Published (Version of record) Open Access

Abstract

Sleep is an ancient animal behavior that is regulated similarly in species ranging from flies to humans. Various genes that regulate sleep have been identified in invertebrates, but whether the functions of these genes are conserved in mammals remains poorly explored. Drosophila insomniac (inc) mutants exhibit severely shortened and fragmented sleep. Inc protein physically associates with the Cullin-3 (Cul3) ubiquitin ligase, and neuronal depletion of Inc or Cul3 strongly curtails sleep, suggesting that Inc is a Cul3 adaptor that directs the ubiquitination of neuronal substrates that impact sleep. Three proteins similar to Inc exist in vertebrates-KCTD2, KCTD5, and KCTD17-but are uncharacterized within the nervous system and their functional conservation with Inc has not been addressed. Here we show that Inc and its mouse orthologs exhibit striking biochemical and functional interchangeability within Cul3 complexes. Remarkably, KCTD2 and KCTD5 restore sleep to inc mutants, indicating that they can substitute for Inc in vivo and engage its neuronal targets relevant to sleep. Inc and its orthologs localize similarly within fly and mammalian neurons and can traffic to synapses, suggesting that their substrates may include synaptic proteins. Consistent with such a mechanism, inc mutants exhibit defects in synaptic structure and physiology, indicating that Inc is essential for both sleep and synaptic function. Our findings reveal that molecular functions of Inc are conserved through ~600 million years of evolution and support the hypothesis that Inc and its orthologs participate in an evolutionarily conserved ubiquitination pathway that links synaptic function and sleep regulation.
Synapses - physiology Humans Mice, Inbred C57BL Sleep - genetics Drosophila Proteins - chemistry Drosophila Proteins - metabolism Drosophila - physiology Potassium Channels - genetics Protein Transport Cullin Proteins - genetics Potassium Channels - metabolism Animals Synapses - metabolism HEK293 Cells Conserved Sequence Cullin Proteins - metabolism Potassium Channels - chemistry Mice Drosophila - metabolism Drosophila Proteins - genetics Drosophila - genetics Evolution, Molecular

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