Temporal depolarization of mitochondria during M phase

Abstract

Mitochondrial activity in cells must be tightly controlled in response to changes in intracellular circumstances. Despite drastic changes in intracellular conditions and mitochondrial morphology, it is not clear how mitochondrial activity is controlled during M phase of the cell cycle. Here, we show that mitochondrial activity is drastically changed during M phase. Mitochondrial membrane potential changed during M phase progression. Mitochondria were polarized until metaphase to the same extent as mitochondria in interphase cells, but were depolarized at around telophase and cytokinesis. After cytokinesis, mitochondrial membrane potential was recovered. In addition, the generation of superoxide anions in mitochondria was significantly reduced at metaphase even in the presence of antimycin A, an inhibitor of complex III. These results suggest that the electron supply to the mitochondrial electron transfer chain is suppressed during M phase. This suppression might decrease the reactive oxygen species generated by the fragmentation of mitochondria during M phase.

The Phosphorylation Status of Drp1-Ser637 by PKA in Mitochondrial Fission Modulates Mitophagy via PINK1/Parkin to Exert Multipolar Spindles Assembly during Mitosis

“…The effects of ROT on mitochondrial dysfunction in cancer have been reported [ 17 ]. Cell damage induced by AA results from the inhibition of electron transfer through the ETC [ 37 ], especially for the Mdivi-1-driven mitochondrial apoptotic pathway [ 38 ]. However, to our knowledge, there is no previous study examining the relationship between mitochondrial fission and cell cycle after ROT, AA, and Mdivi-1 administration in HeLa cells.…”

A protonic biotransducer controlling mitochondrial ATP synthesis

“…Fluorescence from BCECF is collected between 515 and 550 nm. Total fluorescence of F 480 and F 405 from individual mitochondria are obtained as integrated fluorescence as described previously 41 . The fluorescence ratio (F 480 /F 405 ) is measured in the presence of 5 µM carbonyl cyanide m-chlorophenyl hydrazine (CCCP) at the different solution pH (6.8, 7.3, 7.8, 8.3 and 8.8) to equilibrate the pH between buffer solution and mitochondrial matrix.…”

Effects of Matrix pH on Spontaneous Transient Depolarization and Reactive Oxygen Species Production in Mitochondria

“…Briefly, the isolated mitochondria were stained with 2 nM TMRE in Tris-HCl buffer for 10 min in the presence of 1 mg/mL BSA at 25°C ( Hattori et al, 2005 ; Shibata et al, 2019 ). To measure the mitochondria in H9c2 cells, the cells were stained with 10 nM TMRE in HEPES-buffered saline (HBS; 10 mM HEPES, 120 mM NaCl, 4 mM KCl, 0.5 mM MgSO 4 , 1 mM NaH 2 PO 4 , 4 mM NaHCO 3 , 25 mM glucose, 1.2 mM CaCl 2 , and 0.1% BSA, pH 7.4) for 30 min at 37°C ( Hirusaki et al, 2017 ). Then, the glass-bottom culture dish with isolated mitochondria or cells was placed on the stage of an inverted epifluorescence microscope (IX-70; Olympus; Tokyo, Japan).…”

“…To analyze the changes in Δψ m of individual intracellular mitochondria, time-lapse images of TMRE fluorescence in the cells were obtained for 90 s with a 40 × objective lens and were analyzed using MetaMorph. Transient depolarization was identified as a decrease greater than 15% of the average intensity in an area >1.0 μm 2 within 3 s. To estimate the Δψ m in a whole cell, the TMRE fluorescence was integrated over the entire cell ( Hirusaki et al, 2017 ) and represented as the percentage of the integrated cellular fluorescence to the average of the integrated fluorescence of control cells (Cell TMRE). We selected cells that were not in contact with surrounding cells to obtain the whole-cell fluorescence and to calculate the integrated fluorescence intensity.…”

“…BCECF fluorescence was recorded between 515 and 550 nm. Fluorescence images of the dye illuminated with a shorter wavelength (F S ) and a longer wavelength (F L ) were obtained every 1 min and analyzed as integrated fluorescence, as described previously ( Hirusaki et al, 2017 ).…”