GSE201732
Circadian ribosome profiling reveals a role for the Period2 upstream opening reading frame in sleep
Many mammalian proteins have circadian cycles of production and degradation, but de novo transcription is only responsible for a small fraction of this rhythmicity. We used ribosome profiling to quantify RNA translation in liver from circadian-entrained mice transferred to constant darkness conditions over a 24-h period and compared translation levels to absolute protein production for 16 circadian proteins. We observed a delay between translation and peak protein levels for several circadian genes covering a wide range of translation efficiencies. We found extensive binding of ribosomes to upstream open reading frames (uORFs) in circadian mRNAs, including the core clock gene Period2 (Per2). Increased uORFs in 5' UTRs was associated with decreased ribosome binding in downstream ORFs and reduced expression of synthetic reporter constructs in vitro and in single cells. Mutation of the Per2 uORF increased luciferase and fluorescence reporter expression in 3T3 cells without altering phase or period. Genomic Per2 uORF mutation using CRISPR/Cas9 increased PER2 expression in PER2:Luc MEFs and reduced sleep in Per2 uORF mutant mice. These results suggest that post-transcriptional processes shape translation of mRNA transcripts, which can impact physiological rhythms and sleep. Overall design: Circadian ribosome profiling of two C57BL/6N mouse livers from each timepoint CT00, CT04, CT08, CT12, CT16, CT20, and CT24