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

随着对良好睡眠的重视程度的提高，人们越来越有兴趣了解睡眠/清醒行为是如何控制的。然而，到目前为止，在分子水平上对睡眠和觉醒的调节机制仍然不清楚。这项研究是基于我们之前发现的SIK3激酶作为睡眠稳态的关键调节因子。我们确定了几个SIK3底物分子，在这些分子中，SIK3诱导的这些蛋白的磷酸化将它们定位于细胞质，并导致核内靶基因表达的下调。我们观察到功能丧失突变和磷缺乏SIK3底物小鼠的异常睡眠和觉醒行为。功能丧失的突变体表现出睡眠时间和睡眠需求的增加，这与Sik3-Sleepy突变体的表型一致。另一方面，缺磷突变体表现出觉醒增加，睡眠需要标记减少。这些结果提示，SIK3级联反应可能是睡眠需要调节的重要分子途径。为了研究睡眠调节中负责任的神经细胞群体，我们建立了与CRE驱动的小鼠交配时诱导有条件地敲除目标基因的小鼠。睡眠时间和睡眠需要的调节可能由不同的神经元和细胞类型控制，这似乎是合理的。选择了几个CRE驱动品系与被驱赶的小鼠交配，并检查了任何睡眠参数的变化。我们正在利用这些新建立的小鼠系继续研究SIK3底物在脑区和细胞类型特异性方式中的作用。

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.