The cell cycle is a crucial biological process that is involved in cell growth, development, and reproduction. It can be divided into G1, S, G2, and M phases, and each period is closely regulated to ensure the production of two similar daughter cells with the same genetic material. However, many obstacles influence the cell cycle, including the R-loop that is formed throughout this process. R-loop is a triple-stranded structure, composed of an RNA: DNA hybrid and a single DNA strand, which is ubiquitous in organisms from bacteria to mammals. The existence of the R-loop has important significance for the regulation of various physiological processes. However, aberrant accumulation of R-loop due to its limited resolving ability will be detrimental for cells. For example, DNA damage and genomic instability, caused by the R-loop, can activate checkpoints in the cell cycle, which in turn induce cell cycle arrest and cell death. At present, a growing number of factors have been proven to prevent or eliminate the accumulation of R-loop thereby avoiding DNA damage and mutations. Therefore, we need to gain detailed insight into the R-loop resolution factors at different stages of the cell cycle. In this review, we review the current knowledge of factors that play a role in resolving the R-loop at different stages of the cell cycle, as well as how mutations of these factors lead to the onset and progression of diseases.

中文翻译：

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R 环和疾病：细胞周期很重要

细胞周期是涉及细胞生长、发育和繁殖的重要生物过程。可分为G1、S、G2和M期，每个时期都受到严格调控，以确保产生两个具有相同遗传物质的相似子细胞。然而，许多障碍会影响细胞周期，包括整个过程中形成的 R 环。 R环是一种三链结构，由RNA：DNA杂合体和单条DNA链组成，在从细菌到哺乳动物的生物体中普遍存在。 R环的存在对于多种生理过程的调节具有重要意义。然而，由于其有限的解析能力，R 环的异常积累将对细胞有害。例如，由 R 环引起的 DNA 损伤和基因组不稳定可以激活细胞周期中的检查点，进而诱导细胞周期停滞和细胞死亡。目前，越来越多的因素已被证明可以防止或消除R环的积累，从而避免DNA损伤和突变。因此，我们需要详细了解细胞周期不同阶段的 R 环分辨率因子。在这篇综述中，我们回顾了目前对细胞周期不同阶段在解决 R 环中发挥作用的因素的认识，以及这些因素的突变如何导致疾病的发生和进展。