Grosser, Joshua A.; Maes, Margaret EIST Austria ; Nickells, Robert W.
Recent advancements in live cell imaging technologies have identified the phenomenon of intracellular propagation of late apoptotic events, such as cytochrome c release and caspase activation. The mechanism, prevalence, and speed of apoptosis propagation remain unclear. Additionally, no studies have demonstrated propagation of the pro-apoptotic protein, BAX. To evaluate the role of BAX in intracellular apoptotic propagation, we used high speed live-cell imaging to visualize fluorescently tagged-BAX recruitment to mitochondria in four immortalized cell lines. We show that propagation of mitochondrial BAX recruitment occurs in parallel to cytochrome c and SMAC/Diablo release and is affected by cellular morphology, such that cells with processes are more likely to exhibit propagation. The initiation of propagation events is most prevalent in the distal tips of processes, while the rate of propagation is influenced by the 2-dimensional width of the process. Propagation was rarely observed in the cell soma, which exhibited near synchronous recruitment of BAX. Propagation velocity is not affected by mitochondrial volume in segments of processes, but is negatively affected by mitochondrial density. There was no evidence of a propagating wave of increased levels of intracellular calcium ions. Alternatively, we did observe a uniform increase in superoxide build-up in cellular mitochondria, which was released as a propagating wave simultaneously with the propagating recruitment of BAX to the mitochondrial outer membrane.
This work was supported by National Institute of Health grants R01 EY030123, P30 EY016665, and T32 GM081061, an unrestricted research grant from Research to Prevent Blindness, Inc., and the Frederick A. Davis Endowment from the Department of Ophthalmology and Visual Sciences at the University of Wisconsin-Madison.
Grosser JA, Maes ME, Nickells RW. Characteristics of intracellular propagation of mitochondrial BAX recruitment during apoptosis. Apoptosis. 2021;26(2):132-145. doi:10.1007/s10495-020-01654-w
Grosser, J. A., Maes, M. E., & Nickells, R. W. (2021). Characteristics of intracellular propagation of mitochondrial BAX recruitment during apoptosis. Apoptosis. Springer Nature. https://doi.org/10.1007/s10495-020-01654-w
Grosser, Joshua A., Margaret E Maes, and Robert W. Nickells. “Characteristics of Intracellular Propagation of Mitochondrial BAX Recruitment during Apoptosis.” Apoptosis. Springer Nature, 2021. https://doi.org/10.1007/s10495-020-01654-w.
J. A. Grosser, M. E. Maes, and R. W. Nickells, “Characteristics of intracellular propagation of mitochondrial BAX recruitment during apoptosis,” Apoptosis, vol. 26, no. 2. Springer Nature, pp. 132–145, 2021.
Grosser JA, Maes ME, Nickells RW. 2021. Characteristics of intracellular propagation of mitochondrial BAX recruitment during apoptosis. Apoptosis. 26(2), 132–145.
Grosser, Joshua A., et al. “Characteristics of Intracellular Propagation of Mitochondrial BAX Recruitment during Apoptosis.” Apoptosis, vol. 26, no. 2, Springer Nature, 2021, pp. 132–45, doi:10.1007/s10495-020-01654-w.