No abstract

Photo-caged methodologies have been indispensable for elucidating the functional mechanisms of pharmacologically active molecules at the cellular level. A photo-triggered removable unit enables control of the photo-induced expression of pharmacologically active molecular function, resulting in a rapid increase in the concentration of the bioactive compound near the target cell. However, caging the target bioactive compound generally requires specific heteroatom-based functional groups, limiting the types of molecular structures that can be caged. We have developed an unprecedented methodology for caging/uncaging on carbon atoms using a unit with a photo-cleavable carbon−boron bond. The caging/uncaging process requires installation of the CH 2 −B group on the nitrogen atom that formally assembles an N-methyl group protected with a photoremovable unit. N-Methylation proceeds by photoirradiation via carbon-centered radical generation. Using this radical caging strategy to cage previously uncageable bioactive molecules, we have photocaged molecules with no general labeling sites, including acetylcholine, an endogenous neurotransmitter. Caged acetylcholine provides an unconventional tool for optopharmacology to clarify neuronal mechanisms on the basis of photo-regulating acetylcholine localization. We demonstrated the utility of this probe by monitoring uncaging in HEK cells expressing a biosensor to detect ACh on the cell surface, as well as Ca 2+ imaging in Drosophila brain cells (ex vivo).

Epithelial‐to‐mesenchymal transition (EMT) of carcinoma cells is a promising target for cancer therapy since it is closely related to tumor metastasis and therapeutic resistance. The process of EMT is strongly associated with epigenetic alterations in cancer cells. In addition, recent accumulating evidence suggests that EMT also has a significant influence on inducing cancer stem cells (CSCs). In this study, novel polymer core–lipid shell nanoparticles (PLNPs) are prepared to suppress cancer EMT by the combined effects of the antioxidant activity of core‐encapsulated Mn imidazolium porphyrin (MnImP) and the epigenetic control by histone acetyltransferase‐encoding plasmid DNA (pHAT) hybridized onto the shell surface. PLNPs show the ability to control the expression of EMT‐related markers, resulting in the suppression of EMT in lung epithelial cancer cells (paraquat‐treated A549 cells). Furthermore, PLNPs suppress the levels of intracellular mitochondrial ROS and the transformation to CSCs. The results of this study may provide a novel therapeutic strategy against tumor metastasis and treatment resistance.

Fluorescence thermometry is a microscopy technique in which a fluorescent temperature sensor records temperature changes as alterations of fluorescence signals. Fluorescence lifetime imaging (FLIM) is a promising method for quantitative analysis of intracellular temperature. Recently, we developed small-molecule thermometers, termed Organelle Thermo Greens, that target various organelles and achieved quantitative temperature mapping using FLIM. Despite its highly quantitative nature, FLIM-based thermometry cannot be used widely due to expensive instrumentation. Here, we investigated the applicability and limitations of fluorescence intensity (FI)-based analysis, which is more commonly used than FLIM-based thermometry. Temperature gradients generated by artificial heat sources and physiological heat produced by brown adipocytes were visualized using FI- and FLIM-based thermometry. By comparing the two thermometry techniques, we examined how the shapes of organelles and cells affect the accuracy of the temperature measurements. Based on the results, we concluded that FI-based thermometry could be used for “qualitative”, rather than quantitative, thermometry under the limited condition that the shape change and the dye leakage from the target organelle were not critical.