A signalling pathway for transcriptional regulation of sleep amount in mice

In mice and humans, sleep quantity is governed by genetic factors and exhibits age-dependent variation 1 – 3 . However, the core molecular pathways and effector mechanisms that regulate sleep duration in mammals remain unclear. Here, we characterize a major signalling pathway for the transcriptional regulation of sleep in mice using adeno-associated virus-mediated somatic genetics analysis 4 . Chimeric knockout of LKB1 kinase—an activator of AMPK-related protein kinase SIK3 5 – 7 —in adult mouse brain markedly reduces the amount and delta power—a measure of sleep depth—of non-rapid eye movement sleep (NREMS). Downstream of the LKB1–SIK3 pathway, gain or loss-of-function of the histone deacetylases HDAC4 and HDAC5 in adult brain neurons causes bidirectional changes of NREMS amount and delta power. Moreover, phosphorylation of HDAC4 and HDAC5 is associated with increased sleep need, and HDAC4 specifically regulates NREMS amount in posterior hypothalamus. Genetic and transcriptomic studies reveal that HDAC4 cooperates with CREB in both transcriptional and sleep regulation. These findings introduce the concept of signalling pathways targeting transcription modulators to regulate daily sleep amount and demonstrate the power of somatic genetics in mouse sleep research.