Spatio-temporal regulation of signalling pathways plays a key role in generating diverse responses during the development of multicellular organisms. The role of signal dynamics in transferring signalling information in vivo is incompletely understood. Here, we employ genome engineering in Drosophila melanogaster to generate a functional optogenetic allele of the Notch ligand Delta (opto-Delta), which replaces both copies of the endogenous wild-type locus. Using clonal analysis, we show that optogenetic activation blocks Notch activation through cis-inhibition in signal-receiving cells. Signal perturbation in combination with quantitative analysis of a live transcriptional reporter of Notch pathway activity reveals differential tissue- and cell-scale regulatory modes. While at the tissue-level the duration of Notch signalling determines the probability with which a cellular response will occur, in individual cells Notch activation acts through a switch-like mechanism. Thus, time confers regulatory properties to Notch signalling that exhibit integrative digital behaviours during tissue differentiation.

中文翻译：

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Delta的光遗传学抑制揭示了组织分化过程中数字Notch信号输出。

信号通路的时空调节在多细胞生物体发育过程中产生各种反应中起着关键作用。信号动力学在体内传递信号信息中的作用尚不完全清楚。在这里，我们采用果蝇果蝇的基因组工程来生成Notch配体Delta（光合Delta）的功能性光遗传等位基因，它取代了内源性野生型基因座的两个拷贝。使用克隆分析，我们表明，光遗传学激活通过信号接收细胞中的顺式抑制来阻断Notch激活。信号扰动结合对Notch通路活性的实时转录报道基因的定量分析揭示了不同的组织和细胞规模调节模式。虽然在组织水平上，Notch信号传导的持续时间决定了发生细胞应答的可能性，但在单个细胞中，Notch激活是通过开关样机制起作用的。因此，时间赋予Notch信号调节特性，这些信号在组织分化过程中表现出整合的数字行为。