In Situ Monitoring of Mitochondria Regulating Cell Viability by the RNA-Specific Fluorescent Photosensitizer

Abstract

Cell viability is greatly affected by external stimulus eliciting correlated dynamical physiological processes for cells to choose survival or death. A few fluorescent probes have been designed to detect whether the cell is in survival state or apoptotic state, but monitoring the regulation process of the cell undergoing survival to death remains a long-standing challenge. Herein, we highlight the in situ monitor of mitochondria regulating the cell viability by the RNA-specific fluorescent photosensitizer L. At normal conditions, L anchored mitochondria and interacted with mito-RNA to light up the mitochondria with red fluorescence. With external light stimulus, L generated reactive oxide species (ROS) and cause damage to mitochondria, which activated mitochondrial autophagy to prevent death, during which the red fluorescence of L witnessed dynamical distribution in accordance with the evolution of vacuole structures containing damaged mitochondria into autophagosomes. However, with ROS continuously increasing, the mitochondrial apoptosis was eventually commenced and L with red fluorescent was gradually accumulated in the nucleoli, indicating the programmed cell death. This work demonstrated how the delicate balance between survival and death are regulated by mitochondria.

Fluorescent Carbon Dots Shuttling between Mitochondria and the Nucleolus for in Situ Visualization of Cell Viability

“…3 Moreover, cell viability usually fluctuates with different external stimuli. 4 Besides, mitochondria and the nucleolus play significant roles in regulating cell viability in various biological processes. For instance, mitochondria are implicated in many biological processes including cellular differentiation, produce adenosine triphosphate, and cause apoptosis.…”

“…Additionally, cell viability testing has many other functions such as the assessment of antitumor drug efficiency, the screening of drugs, and cytotoxicity testing of biological reagents containing fluorophores, nanomaterials, and antibiotics . Moreover, cell viability usually fluctuates with different external stimuli . Besides, mitochondria and the nucleolus play significant roles in regulating cell viability in various biological processes.…”

Polarity-Sensitive Probe: Dual-Channel Visualization of the “Chameleon” Migration with the Assistance of Reactive Oxygen Species

“…Additionally, the faint fluorescence appeared in cells under white irradiation, manifesting that DPDO-C could generate a small amount of ROS. At the same time, JC-10 was used to monitor the mitochondrial member potential. , As shown in Figure S17, upon photoirradiation, the red fluorescence of the cells co-incubated with DPDO-C became weak, while the green fluorescence increased gradually, indicating that the mitochondrial membrane potential of the cells was disrupted. Based on the above results, we could conclude that the migration from mitochondria to LDs of DPDO-C was ascribed to the membrane potential disruption induced by less ROS under a short irradiation time, which inspired us to monitor the diseases (fatty liver, inflammation, etc.)…”

Common methods in mitochondrial research (Review)

“…Under pathological conditions, the balance between the intracellular antioxidant system and oxygen radicals is disrupted. When intracellular ROS levels are too high, mitochondrial structure and function are impaired and cytochrome c is released through mPTP, resulting in damage to mitochondrial enzymes, lipids and nucleic acids as well as oxidative stress (303,(306)(307)(308)(309)(310). ROS can also attack mitochondrial dNA (mtdNA) to produce oxidative damage, resulting in reduced mitochondrial ATP synthesis and MMP damage.…”

“…The chemical reaction method is characterized by high sensitivity, low cost and simple operation; however, it has poor specificity and measurement results are easily affected by some redox reactions or enzyme-catalyzed reactions. Tetranitromethane, nitrotetrazolium blue chloride (NBT), cytochrome c, epinephrine and reduced coenzyme I are commonly used for spectrophotometric methods; these react with superoxide anion radicals to produce ferrous cytochromes with a specific absorbance (detectable at a wavelength of 550 nm), which can be used to directly measure ROS levels (307,(314)(315)(316)(317). The NBT assay is highly sensitive and is commonly used for the histochemical localization of oxygen radicals; however, it is difficult to measure dynamic changes in oxygen radicals in cells or aqueous systems.…”