A role for cryptochromes in sleep regulation

• Published in: BMC neuroscience Vol. 3; no. 1; p. 20
• Main Authors: Wisor, Jonathan P, O'Hara, Bruce F, Terao, Akira, Selby, Chris P, Kilduff, Thomas S, Sancar, Aziz, Edgar, Dale M, Franken, Paul
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 20.12.2002; BioMed Central; BMC
• Subjects: Animals; ARNTL Transcription Factors; Basic Helix-Loop-Helix Transcription Factors; Casein Kinases; Cell Cycle Proteins; circadian genes; Circadian Rhythm - physiology; CLOCK Proteins; Cryptochromes; Darkness; Delta Rhythm; DNA-Binding Proteins; Drosophila Proteins; EEG slow-wave activity; Eye Proteins; Flavoproteins - physiology; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; Nuclear Proteins - genetics; Nuclear Proteins - metabolism; oscillatory network of transcriptional factors; Period Circadian Proteins; Phenotype; Photoreceptor Cells, Invertebrate; Protein Kinases - genetics; Protein Kinases - metabolism; Rats; Rats, Wistar; Receptors, G-Protein-Coupled; RNA, Messenger - metabolism; Sleep - physiology; Sleep Deprivation - metabolism; Trans-Activators - genetics; Trans-Activators - metabolism; Transcription Factors - genetics; Transcription Factors - metabolism; Wakefulness
• ISSN: 1471-2202; 1471-2202
• DOI: 10.1186/1471-2202-3-20

The cryptochrome 1 and 2 genes (cry1 and cry2) are necessary for the generation of circadian rhythms, as mice lacking both of these genes (cry1,2-/-) lack circadian rhythms. We studied sleep in cry1,2-/- mice under baseline conditions as well as under conditions of constant darkness and enforced wakefulness to determine whether cryptochromes influence sleep regulatory processes. Under all three conditions, cry1,2-/- mice exhibit the hallmarks of high non-REM sleep (NREMS) drive (i.e., increases in NREMS time, NREMS consolidation, and EEG delta power during NREMS). This unexpected phenotype was associated with elevated brain mRNA levels of period 1 and 2 (per1,2), and albumin d-binding protein (dbp), which are known to be transcriptionally inhibited by CRY1,2. To further examine the relationship between circadian genes and sleep homeostasis, we examined wild type mice and rats following sleep deprivation and found increased levels of per1,2 mRNA and decreased levels of dbp mRNA specifically in the cerebral cortex; these changes subsided with recovery sleep. The expression of per3, cry1,2, clock, npas2, bmal1, and casein-kinase-1epsilon did not change with sleep deprivation. These results indicate that mice lacking cryptochromes are not simply a genetic model of circadian arrhythmicity in rodents and functionally implicate cryptochromes in the homeostatic regulation of sleep.