Regulation of Sleep Amount by CRTC1 via Transcription of Crh in Mice

The cAMP response element binding protein (CREB) is required for regulation of daily sleep amount, whereas gain of function of CREB-regulated transcription coactivator 1 (CRTC1) causes severe insomnia in mice. However, the physiological functions of CRTCs and their downstream target genes in the regulation of sleep amount remain unclear. Here, we use an adult brain chimeric (ABC)-expression/knock-out platform for somatic genetic analysis of sleep in adult male mice. ABC expression of constitutively active mutant CRTC1/2CA in the mouse brain neurons significantly reduces the amount of non-rapid eye movement sleep (NREMS) and/or rapid eye movement sleep (REMS). Consistent with the fact that SIK3 phosphorylates and inhibits CRTCs, ABC expression of CRTC1/2/3CA rescues the hypersomnia phenotype of Sleepy (Sik3Slp) mice. WhileABCCrtc2KO or Crtc3KO causes no sleep phenotype,ABCCrtc1KO or ABC expression of dominant-negative CRTC (dnCRTC) results in a modest reduction of NREMS amount accompanied with elevated NREMS delta power. Moreover, ABC expression of CRTC1CA or dnCRTC in the excitatory neurons causes bidirectional changes of NREMS/REMS amount and/or NREMS delta power. The ability of CRTC1CA to regulate sleep requires its transactivation domain and CREB-binding domain and is dependent on CREB. Furthermore, we showed that inducible ABC expression of corticotropin-releasing hormone (Crh) and brain-derived neurotrophic factor (Bdnf)-two target genes of CRTCs-significantly reduces daily sleep amount. Notably, ABC-CrhKO, but not Bdnf KO, rescues the insomnia phenotype of ABCCRTC1CA mice. Taken together, these results indicate that the CREB-CRTC1 complex regulates daily sleep amount by modulating the transcription of Crh in the mouse brain neurons.