Single Image Capture of Bioactive Ion Crosstalk within Inter‐Organelle Membrane Contacts at Nanometer Resolution

Abstract

mitochondria and lysosomes, thus regulating numerous cellular processes, most notably those involved in the maintenance of cellular homeostasis. [3][4][5][6][7][8][9][10][11] Moreover, the mounting evidence implicates the breakdown in mitochondria-lysosome interorganelle cross-talk as relevant in number of human pathologies, most notably neurodegenerative disease, such as Parkinson's disease. [3] Therefore, understanding MLC processes and the key molecules involved in mediating inter-organelle communication in normal cellular physiology as well as disease is of critical importance.Due to the limitation of Abel diffraction, the structure of subcellular organelles below 200 nm cannot be observed by a traditional fluorescence microscope. [12,13] Recently developed super-resolution imaging technology, such as structured illumination microscopy (SIM) [14][15][16] has been widely used for organelle interaction analysis to reveal the involvement of Ca 2+ in MLCs through capturing various time-lapse images. [17] Although this study captured Ca 2+ dynamics through the acquisition of time-lapse images, this required continuous laser irradiation, thus destroying the quantum yield of fluorescence. [12,18,19] This effect, also known as photobleaching, represents a major Rapid bioactive ion exchange is a form of communication that regulates a wide range of biological processes. Despite advances in super-resolution optical microscopy, visualizing ion exchange remains challenging due to the extremely fast nature of these events. Here, a "converting a dynamic event into a static image construction" (CDtSC) strategy is developed that uses the color transformation of a single dichromatic molecular probe to visualize bioactive ion inter-organelle exchange in live cells. As a proof of concept, a reactive sulfur species (RSS) is analyzed at the mitochondria-lysosome contact sites (MLCs). A non-toxic and sensitive probe based on coumarin-hemicyanine structure is designed that responds to RSS localized in both mitochondria and lysosomes while fluorescing different colors. Using this probe, RSS give-and-take at MLCs is visualized, thus providing the first evidence that RSS is involved in inter-organelle contacts and communication. Taken together, the CDtSC provides a strategy to visualize and analyze rapid inter-organelle ion exchange events in live cells at nanometer resolution.

In situ visualization of the cellular uptake and sub-cellular distribution of mussel oligosaccharides

“…After shaking for 2 h, the absorption wavelength of each well was measured at 450 nm by an enzyme labeling apparatus (BioTek Synergy HTX; Agilent Technologies, Inc., Beijing, China). Cell viability (%) was calculated by the mean absorbance value of the treatment group divided by the mean absorbance value of the control group [ 27 , 28 ].…”

Drug delivery system for the extended-release of larotrectinib based on a biocompatible Fe-based metal-organic framework: synthesis, characterization, in vitro release properties and antitumor evaluation

“…The 96-well plate medium was discarded, and the cells were washed twice with PBS. Media containing different concentrations of Fe-MOF (0.5–50 μg/mL) were then added to each well and incubated for 24 h. Cell viability was determined using the MTT assay according to standard protocols ( Javad Farhangi et al, 2021 ; Liu et al, 2021 ; Fang et al, 2022 ; Ji et al, 2022 ).…”

Small-molecule fluorogenic probes for mitochondrial nanoscale imaging

“…Furthermore, Fang et al reported another hemicyanine-based fluorogenic probe, CHS , with good solubility due to the sulfonic acids, which responded to mitochondrial ( λ em = 493 nm) and lysosomal ( λ em = 674 nm) RSS by emitting different fluorescence wavelengths. 176 This probe enabled the visualization of mutual RSS alterations, establishing the role of RSS in intercellular organelle interaction (Table 2).…”