Mitochondrial cristae changes in insulin-secreting INS-1E cells as reflected by 3D super-resolution dSTORM microscopy A. Dlasková1*, A. Kahancová1, H. Engstová1, T. Špaček1, P. Ježek1 1Institute of Physiology, Department of Mitochondrial Physiology, Vídeňská 1083, 14220 Prague 4, Czech Republic *Corresponding Author: andrea.dlaskova@fgu.cas.cz 3D super-resolution microscopy represents a powerful method for accessing ultrastructural changes of objects that could be normally resolved only by electron microscopy. In this work, we applied the direct stochastic optical reconstruction microscopy (dSTORM) with fluorescently labeled primary antibodies against ATP-synthase F1 subunit alpha (F1-alpha) and monitored mitochondrial cristae changes in pancreatic β-cells. Obtained 3D images were analyzed with the help of Ripley's K-function and from it derived distance distribution function. Resulting histograms provided most frequent distances (MFD) between the localized single antibody molecules [1]. In fasting state MFD between F1-alpha were ~80 nm at 0 and 3 mM glucose, whereas decreased to 61 nm and 57 nm upon glucose-stimulated insulin secretion (GSIS) at 11 mM and 20 mM glucose, respectively. Shorter F1-alpha interdistances well corresponded to decrease in cristae width upon GSIS. Namely, cristae width estimated by transmission electron microscopy was 20 nm and 15 nm at 0 and 3 mM glucose and 9 nm or 8 nm after GSIS (11, 20 mM glucose, respectively). We also demonstrate that changes in cristae width are accompanied by concomitant changes in ATP synthase oligomerization. We conclude that the observed modulation of mitochondrial cristae width by glucose levels might represent regulatory mechanism of mitochondrial OXPHOS efficiency and might be critical for appropriate glucose sensing by pancreatic β-cells.
Supported by GACR 17- 08565S grant. [1] Dlasková A, Engstová H, Špaček T, Kahancová A, Smolková K, Špačková J, Plecitá-Hlavatá L, and Ježek P. 3D super-resolution microscopy reflects mitochondrial cristae and mt nucleoid morphology changes. Biochim. Biophys. Acta special issue EBEC 2018.
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