Genome-Wide Screen for Genes Involved in Caenorhabditis elegans Developmentally Timed Sleep

Abstract

In Caenorhabditis elegans, Notch signaling regulates developmentally timed sleep during the transition from L4 larval stage to adulthood (L4/A) . To identify core sleep pathways and to find genes acting downstream of Notch signaling, we undertook the first genome-wide, classical genetic screen focused on C. elegans developmentally timed sleep. To increase screen efficiency, we first looked for mutations that suppressed inappropriate anachronistic sleep in adult hsp:: osm-11 animals overexpressing the Notch coligand OSM-11 after heat shock. We retained suppressor lines that also had defects in L4/A developmentally timed sleep, without heat shock overexpression of the Notch coligand. Sixteen suppressor lines with defects in developmentally timed sleep were identified. One line carried a new allele of goa-1 ; loss of GOA-1 Gα _o decreased C. elegans sleep. Another line carried a new allele of gpb-2 , encoding a Gβ ₅ protein; Gβ ₅ proteins have not been previously implicated in sleep. In other scenarios, Gβ ₅ GPB-2 acts with regulators of G protein signaling (RGS proteins) EAT-16 and EGL-10 to terminate either EGL-30 Gα _q signaling or GOA-1 Gα _o signaling, respectively. We found that loss of Gβ ₅ GPB-2 or RGS EAT-16 decreased L4/A sleep. By contrast, EGL-10 loss had no impact. Instead, loss of RGS-1 and RGS-2 increased sleep. Combined, our results suggest that, in the context of L4/A sleep, GPB-2 predominantly acts with EAT-16 RGS to inhibit EGL-30 Gαq signaling. These results confirm the importance of G protein signaling in sleep and demonstrate that these core sleep pathways function genetically downstream of the Notch signaling events promoting sleep.