Spatiotemporal regulation of microRNA-mediated gene silencing in cells.

MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression by silencing mRNAs with complementary sequences. Over the past few decades, genetic and biochemical studies have revealed the molecular machinery and mechanisms underlying miRNA function. However, the current understanding of their cellular biology remains relatively limited. While the conventional view simplifies the miRNA journey as transcription in the nucleus and function in the cytoplasm, the precise spatiotemporal regulation of miRNAs within the intracellular environment is only beginning to emerge. Accumulating evidence suggests that miRNAs do not merely float in the cytosol, but instead associate with various organelles and biomolecular condensates, potential sites of miRNA regulation. In this review, we summarize the current knowledge regarding how these intracellular compartments relate to miRNA function. Furthermore, we introduce cutting-edge methodologies designed to explore this expanding frontier of miRNA cell biology.Key words: microRNA, mRNA, translation, organelles, single-molecule imaging.