Imaging the Life and Death of mRNAs in Single Cells

RNA plays a central role in gene expression from its transcription in the nucleus through translation and degradation in the cytoplasm. Technological advances in fluorescent microscopy and labeling methodologies have made it possible to detect single molecules of RNA in both fixed and living cells. Here, we focus on the recent developments in RNA imaging that have allowed quantitatively measuring the lives of individual transcripts from birth to death and all the events in between in single cells and tissues. Direct observation of RNAs within their native cellular environment has revealed a complex layer of spatial and temporal regulation that has profoundly impacted our understanding of RNA biology. Outline 1 Visualizing RNA at the single-cell and single-molecule scale 2 smFISH reveals the basic features of gene expression regulation 3 Localization as a gene expression regulator 4 Increasing spatial resolution: Toward structural resolution of mRNPs with light microscopy 5 Optimized in situ techniques to visualize and quantify the diversity of RNAs and their processing at the singlemolecule level 6 Increasing RNA visualization throughput 7 Imaging RNA beyond cultured cells: Recent developments for single-molecule RNA imaging in tissue 8 Imaging RNAs in living cells 9