Endocrine timing of the cell cycle in the zebrafish: The case of glucocorticoids

内分泌信号在正常生理和疾病中起着至关重要的作用。我们知识中的一个主要差距是它们有节奏的、通常是脉动的释放模式如何影响它们在体内的生理靶点的时间，例如细胞分裂周期。此外，人们对这些信令系统在开发过程中如何在功能上成熟知之甚少。在这里，我们建议使用糖皮质激素作为内分泌信号的一个例子来解决这些问题。作为一个模型生理读数，我们将探索最近揭示的糖皮质激素在斑马鱼幼虫昼夜细胞周期进程中的作用的分子机制[1]。我们将使用一套生物传感器来监测完整动物体内的糖皮质激素信号活动和细胞周期进程，以了解肾上腺信号的动态及其对细胞周期进程的影响。在糖皮质激素反应元件的控制下，将使用荧光素酶报告基因来测量糖皮质激素信号，而在细胞周期调节因子Wee1启动子的控制下，将使用荧光素酶报告基因来监测细胞周期进展。生物传感器将使我们能够研究肾上腺信号的成熟和发育过程中的昼夜细胞周期动力学，以及垂体功能受损的突变体。最终，这些生物传感器将成为筛选下丘脑-垂体-肾上腺轴功能紊乱和细胞增殖缺陷突变的有价值的工具。

Endocrine signals play crucial roles in normal physiology and disease. A major gap in our knowledge is how their rhythmic, often pulsatile release patterns impact on timing of their physiological targets in vivo, such as cell division cycles. Furthermore, relatively little is known about how these signalling systems mature functionally during development. Here, we propose to address these questions using glucocorticoids as an example of an endocrine signal. We will explore the molecular mechanisms underlying the recently revealed role of glucocorticoids in timing circadian cell cycle progression in zebrafish larvae [1] as a model physiological readout. We will use a set of biosensors to monitor glucocorticoid signalling activity and cell cycle progression in the intact animal to understand the dynamics of adrenal signals and their effect on cell cycle progression. Glucocorticoid signalling will be measured using a luciferase reporter under control of Glucocorticoid Response Elements, and cell cycle progression will be monitored using a luciferase reporter gene under control of the promoter of the cell cycle regulator Wee1. The biosensors will enable us to study the maturation of adrenal signalling and circadian cell cycle dynamics during development and in mutants with disrupted pituitary function. Ultimately, these biosensor lines will represent a valuable tool to screen for mutants with disrupted hypothalamic-pituitary-adrenal axis function and cell proliferation defects.