Department of Cell Biology, Duke University Medical Center, Durham, NC 27705, USA.
Department of Cell Biology, Duke University Medical Center, Durham, NC 27705, USA.
Curr Biol. 2024 Jun 3;34(11):R519-R523. doi: 10.1016/j.cub.2024.04.044.
Rapid cleavage divisions and the transition from maternal to zygotic control of gene expression are the hallmarks of early embryonic development in most species. Early development in insects, fish and amphibians is characterized by several short cell cycles with no gap phases, necessary for the rapid production of cells prior to patterning and morphogenesis. Maternal mRNAs and proteins loaded into the egg during oogenesis are essential to drive these rapid early divisions. Once the function of these maternal inputs is complete, the maternal-to-zygotic transition (MZT) marks the handover of developmental control to the gene products synthesized from the zygotic genome. The MZT requires three major events: the removal of a subset of maternal mRNAs, the initiation of zygotic transcription, and the remodeling of the cell cycle. In each species, the MZT occurs at a highly reproducible time during development due to a series of feedback mechanisms that tightly couple these three processes. Dissecting these feedback mechanisms and their spatiotemporal control will be essential to understanding the control of the MZT. In this primer, we outline the mechanisms that govern the major events of the MZT across species and highlight the role of feedback mechanisms that ensure the MZT is precisely timed and orchestrated.
快速分裂和从母体到合子控制基因表达的转变是大多数物种早期胚胎发育的标志。昆虫、鱼类和两栖类的早期发育特征是几个短的细胞周期，没有间隙阶段，这对于在模式形成和形态发生之前快速产生细胞是必要的。在卵母细胞发生过程中加载到卵子中的母体 mRNA 和蛋白质对于驱动这些快速早期分裂至关重要。一旦这些母体输入的功能完成，母体到合子的过渡（MZT）标志着将发育控制移交给从合子基因组合成的基因产物。MZT 需要三个主要事件：去除一组母体 mRNA，启动合子转录，以及细胞周期的重塑。在每种物种中，由于一系列紧密偶联这三个过程的反馈机制，MZT 在发育过程中高度可重复地发生在特定时间。剖析这些反馈机制及其时空控制对于理解 MZT 的控制至关重要。在本入门指南中，我们概述了跨物种控制 MZT 的主要事件的机制，并强调了确保 MZT 精确定时和协调的反馈机制的作用。
