Fig. 4.

Cellular redox balance-DNA damage response (DDR)-miRNA triangle. Under various stress conditions, increased ROS production is usually present in different cell compartments, such as the nucleus, cytoplasm, etc., through which ROS and redox signals move to regulate gene expression. ROS accumulation in the nucleus can arrest the cell cycle by inducing DNA damage; however, the DDR reduces the negative effects of DNA damage by modulating the activity of microRNAs. To promote the cell cycle according to the redox environment, altered antioxidant and oxidant balance is required in the nucleus. In this circumstance, ROS and redox signals regulate gene expression at transcriptional and post-transcriptional levels. The picture illustrates redox-dependent transcriptional mechanisms involved in the regulation of redox-sensitive TF (SRG1, PAN, and HSFA8) expression to regulate gene expression affected by ROS/RNS. In fact, at the post-transcriptional level, miRNAs can also target mRNAs (redox- and DDR-related target mRNAs) to inhibit the translation of negative regulation of stress tolerance. miRNA, microRNA; ROS, reactive oxygen species; RNS, reactive nitrogen species; AOx, antioxidants; Ox, oxidants; DCL1, DICER-like1; PAN, perianthia; SRG1, SNO-regulated gene1; HSFA8, heat shock factor A8 [115]. The schematic representation was adapted from Cimini et al. [115].