Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
Development. 2022 May 1;149(9). doi: 10.1242/dev.200173. Epub 2022 May 3.
Diapause arrest in animals such as Caenorhabditis elegans is tightly regulated so that animals make appropriate developmental decisions amidst environmental challenges. Fully understanding diapause requires mechanistic insight of both entry and exit from the arrested state. Although a steroid hormone pathway regulates the entry decision into C. elegans dauer diapause, its role in the exit decision is less clear. A complication to understanding steroid hormonal regulation of dauer has been the peculiar fact that steroid hormone mutants such as daf-9 form partial dauers under normal growth conditions. Here, we corroborate previous findings that daf-9 mutants remain capable of forming full dauers under unfavorable growth conditions and establish that the daf-9 partial dauer state is likely a partially exited dauer that has initiated but cannot complete the dauer exit process. We show that the steroid hormone pathway is both necessary for and promotes complete dauer exit, and that the spatiotemporal dynamics of steroid hormone regulation during dauer exit resembles that of dauer entry. Overall, dauer entry and dauer exit are distinct developmental decisions that are both controlled by steroid hormone signaling.
动物（如秀丽隐杆线虫）的休眠中止受到严格调控，以使动物在环境挑战中做出适当的发育决策。要全面了解休眠，就需要深入了解进入和退出休眠状态的机制。尽管甾体激素途径调节线虫 dauer 休眠的进入决策，但它在退出决策中的作用尚不清楚。理解固醇激素对 dauer 的调节之所以复杂，是因为类固醇激素突变体（如 daf-9）在正常生长条件下形成部分 dauer。在这里，我们证实了先前的发现，即 daf-9 突变体在不利的生长条件下仍能形成完全 dauer，并确定 daf-9 部分 dauer 状态可能是部分退出 dauer，它已经启动但不能完成 dauer 退出过程。我们表明，甾体激素途径对于完全 dauer 退出是必要的和促进的，并且在 dauer 退出过程中甾体激素调节的时空动态与 dauer 进入过程相似。总的来说，dauer 进入和 dauer 退出是由类固醇激素信号控制的两种不同的发育决策。
