Interneurons Regulate Locomotion Quiescence via Cyclic Adenosine Monophosphate Signaling During Stress-Induced Sleep in Caenorhabditis elegans

Abstract

Sleep is evolutionarily conserved, thus studying simple invertebrates such as Caenorhabditis elegans can provide mechanistic insight into sleep with single cell resolution. A conserved pathway regulating sleep across phylogeny involves cyclic adenosine monophosphate (cAMP), a ubiquitous second messenger that functions in neurons by activating protein kinase A. C. elegans sleep in response to cellular stress caused by environmental insults [stress-induced sleep (SIS)], a model for studying sleep during sickness. SIS is controlled by simple neural circuitry, thus allowing for cellular dissection of cAMP signaling during sleep. We employed a red-light activated adenylyl cyclase, IlaC22, to identify cells involved in SIS regulation. We found that pan-neuronal activation of IlaC22 disrupts SIS through mechanisms independent of the cAMP response element binding protein. Activating IlaC22 in the single DVA interneuron, the paired RIF interneurons, and in the CEPsh glia identified these cells as wake-promoting. Using a cAMP biosensor, epac1-camps, we found that cAMP is decreased in the RIF and DVA interneurons by neuropeptidergic signaling from the ALA neuron. Ectopic overexpression of sleep-promoting neuropeptides coded by flp-13 and flp-24, released from the ALA, reduced cAMP in the DVA and RIFs, respectively. Overexpression of the wake-promoting neuropeptides coded by pdf-1 increased cAMP levels in the RIFs. Using a combination of optogenetic manipulation and in vivo imaging of cAMP we have identified wake-promoting neurons downstream of the neuropeptidergic output of the ALA. Our data suggest that sleep-and wake-promoting neuropeptides signal to reduce and heighten cAMP levels during sleep, respectively.

Exploring potential mechanism of ciwujia tablets for insomnia by UPLC-Q-TOF-MS/MS, network pharmacology, and experimental validation

“…In addition, the cAMP signaling pathways, calcium signaling, Gap junction and other related pathways in the GO and KEGG analysis results have also been verified in related reports. As per some studies, sleep and wakefulness are closely related to the expression level of cAMP ( Choi et al, 2016 ; Carev and Sarikurkcu, 2021 ), and it has been previously proved that sleep- and wake-promoting neuropeptide signals could decrease and increase cAMP levels during sleep ( Cianciulli et al, 2019 ). Furthermore, taking into consideration that calcium signaling pathways underlie the regulation of sleep duration in mammals ( Tatsuki et al, 2016 ), damage to this specific pathway will lead to increased wakefulness and abnormal brain rhythms ( Bojarskaite et al, 2020 ).…”

Evolutionary conserved peptide and glycoprotein hormone-like neuroendocrine systems in C. elegans

“…The C. elegans genome encodes two PDF-like precursors (PDF-1 and PDF-2/NLP-37) and a single PDFR ortholog, PDFR-1 ( Beets et al, 2023 ; Janssen et al, 2009a ). C. elegans PDF signaling is involved in arousal, orchestrating circadian rhythm and other rhythmic behaviors, suppressing developmentally timed and stress-induced sleep, promoting mate searching, and stimulating roaming behavior ( Barrios et al, 2012 ; Chew et al, 2018b ; Choi et al, 2013 ; Cianciulli et al, 2019 ; Flavell et al, 2013 ; Herrero et al, 2015 ; Hilbert and Kim, 2018 ; Janssen et al, 2009a ; Meelkop et al, 2012 ; Pfaff et al, 2008 ; Soto et al, 2019 ; Suo et al, 2019 ).…”

Orcokinin neuropeptides regulate sleep in Caenorhabditis elegans

“…Many neuropeptides signal through GPCRs, which increase or decrease signaling of second messenger pathways. Movement quiescence is antagonized by signaling through the cyclic adenosine monophosphate/protein kinase A pathway (Cianciulli et al, 2019). In C. elegans, PKA activity can be experimentally increased by genetic impairment in the gene kin-2, which encodes a regulatory subunit of PKA (Charlie, Thomure, Schade, & Miller, 2006).…”

“…Numerous neuropeptides regulate movement quiescence, including FLP-11, secreted from the RIS (Konietzka et al, 2020) andFLP-13, FLP-24, andNLP-8 (Nath et al, 2016;Nelson et al, 2015), released from ALA. These molecules signal through many GPCRs (Iannacone et al, 2017;Nelson et al, 2015), reducing cAMP/PKA signaling in different cells (Cianciulli et al, 2019). The orcokinins can be added to this expanding list of somnogenic neuropeptides.…”