RNAs play pivotal roles in many biological processes, such as translation, gene editing etc. Since RNAs are usually smaller in size than optical diffraction limit, it is impossible for optical microscopes to get deep insight of them. With the recent emergence of super-resolution optical imaging microscopies, it becomes possible to study the ultra-fine structure of such RNA in side cells. Different kind of fluorescent probes are used for RNA labeling and imaging inside cells. However, most of them cannot be used for live-cell super-resolution imaging, due to typical laser toxicity to live cells. Herein, we developed a new type of RNA-labeled probe, which can be used for STED imaging of RNA in living cells. We believe this probe is of great significance for studying biological behaviors of RNA in living cells.
Unfolded or misfolded protein accumulation inside Endoplasmic Reticulum (ER) will cause ER stress and subsequently will activate cellular autophagy to release ER stress, which would ultimately result in microviscosity changes. However, even though, it is highly significant to gain a quantitative assessment of microviscosity changes during ER autophagy to study ER stress and autophagy behaviors related diseases, it has rarely been reported yet. In this work, we have reported a BODIPY based fluorescent molecular rotor that can covalently bind with vicinal dithiols containing nascent proteins in ER and hence can result in ER stress through the inhibition of the folding of nascent proteins. The change in local viscosity, caused by the release of the stress in cells through autophagy, was quantified by the probe using fluorescence lifetime imaging. This work basically demonstrates the possibility of introducing synthetic chemical probe as a promising tool to diagnose ER-viscosity-related diseases.