Somatic stem/progenitor cells actively proliferate and give rise to different types of mature cells (active state) in embryonic tissues while they are mostly dormant (quiescent state) in many adult tissues. Notch signaling is known to regulate both active and quiescent states of somatic stem cells, but how it regulates these different states is unknown. Recent studies revealed that the Notch effector Hes1 is expressed differently during the active and quiescent states during neurogenesis and myogenesis: high in the quiescent state and oscillatory in the active state. When the Hes1 expression level is high, both Ascl1 and MyoD expression are continuously suppressed. By contrast, when Hes1 expression oscillates, it periodically represses expression of the neurogenic factor Ascl1 and the myogenic factor MyoD, thereby driving Ascl1 and MyoD oscillations. High levels of Hes1 and the resultant Ascl1 suppression promote the quiescent state of neural stem cells, while Hes1 oscillation-dependent Ascl1 oscillations regulate their active state. Similarly, in satellite cells of muscles, known adult muscle stem cells, high levels of Hes1 and the resultant MyoD suppression seem to promote their quiescent state, while Hes1 oscillation-dependent MyoD oscillations activate their proliferation and differentiation. Therefore, the expression dynamics of Hes1 is a key regulatory mechanism of generating and maintaining active/quiescent stem cell states.

中文翻译：

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通过Notch信号调节活跃和静止的体细胞干细胞。

体细胞干/祖细胞活跃增殖并在胚胎组织中产生不同类型的成熟细胞（活跃状态），而它们在许多成年组织中大多处于休眠状态（静止状态）。已知Notch信号传导可调节体干细胞的活跃和静止状态，但是尚不清楚其如何调节这些不同状态。最近的研究表明，Notch效应器Hes1在神经发生和肌生成过程的活跃状态和静止状态中表达不同：处于静止状态时处于高状态，处于活跃状态时处于振荡状态。当Hes1表达水平高时，Ascl1和MyoD表达均被连续抑制。相比之下，当Hes1表达振荡时，它会周期性抑制神经源性因子Ascl1和肌源性因子MyoD的表达，从而驱动Ascl1和MyoD振荡。高水平的Hes1和由此产生的Ascl1抑制作用促进了神经干细胞的静止状态，而Hes1振荡相关的Ascl1振荡调节了它们的活动状态。类似地，在肌肉的卫星细胞中，已知的成年肌肉干细胞，高水平的Hes1和产生的MyoD抑制似乎促进了它们的静止状态，而依赖于Hes1振荡的MyoD振荡激活了它们的增殖和分化。因此，Hes1的表达动力学是产生和维持活性/静态干细胞状态的关键调控机制。在肌肉的卫星细胞中，已知的成年肌肉干细胞，高水平的Hes1和所产生的MyoD抑制似乎促进了它们的静止状态，而依赖于Hes1振荡的MyoD振荡激活了它们的增殖和分化。因此，Hes1的表达动力学是产生和维持活性/静态干细胞状态的关键调控机制。在肌肉的卫星细胞中，已知的成年肌肉干细胞，高水平的Hes1和所产生的MyoD抑制似乎促进了它们的静止状态，而依赖于Hes1振荡的MyoD振荡激活了它们的增殖和分化。因此，Hes1的表达动力学是产生和维持活性/静态干细胞状态的关键调控机制。