新規コンディショナル過眠モデルマウスを用いた睡眠制御分子メカニズムの解明

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There has been increased interest in understanding how sleep/wake behavior is controlled as the emphasis on the well-maintained sleep has grown. However, the regulatory mechanism of sleep and wake at the molecular level remains unclear to date. This study is based on our previous finding of SIK3 kinase as a key regulator of sleep homeostasis. We identified several SIK3 substrate molecules where SIK3-induced phosphorylation of these proteins localizes them to the cytoplasm and result in desuppression of target gene expression in the nucleus. We observed abnormal sleep and wake behavior in the loss-of-function mutants and phosphodeficient SIK3-substrate mice. The loss-of-function mutants showed increased sleep time and sleep need, consistent with the Sik3-Sleepy mutant phenotype. On the other hand, the phosphodeficient mutants showed increased wakefulness with decrease in sleep need marker. These results suggest that the SIK3 cascade may constitute an important molecular pathway in sleep need regulation. To investigate responsible neural population in sleep regulation, we established floxed mice to induce conditional knockout of the target gene when mated with Cre-driver mice. It is plausible that sleep time and sleep need regulation may be controlled by distinct population of neurons and cell types. Several Cre-driver strains were selected to mate with the floxed mice and examined for changes in any sleep parameters. We are proceeding with investigation of the role of SIK3 substrates in brain region- and cell type-specific manner using these newly established mouse line.