Glycogen synthase kinase-3β mediates convergence of protection signaling to inhibit the mitochondrial permeability transition pore
Magdalena Juhaszova, … , Eric N. Olson, Steven J. Sollott
Magdalena Juhaszova, … , Eric N. Olson, Steven J. Sollott
Published June 1, 2004
Citation Information: J Clin Invest. 2004;113(11):1535-1549. https://doi.org/10.1172/JCI19906.
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Categories: Article Cell biology

Glycogen synthase kinase-3β mediates convergence of protection signaling to inhibit the mitochondrial permeability transition pore

Abstract

Environmental stresses converge on the mitochondria that can trigger or inhibit cell death. Excitable, postmitotic cells, in response to sublethal noxious stress, engage mechanisms that afford protection from subsequent insults. We show that reoxygenation after prolonged hypoxia reduces the reactive oxygen species (ROS) threshold for the mitochondrial permeability transition (MPT) in cardiomyocytes and that cell survival is steeply negatively correlated with the fraction of depolarized mitochondria. Cell protection that exhibits a memory (preconditioning) results from triggered mitochondrial swelling that causes enhanced substrate oxidation and ROS production, leading to redox activation of PKC, which inhibits glycogen synthase kinase-3β (GSK-3β). Alternatively, receptor tyrosine kinase or certain G protein–coupled receptor activation elicits cell protection (without mitochondrial swelling or durable memory) by inhibiting GSK-3β, via protein kinase B/Akt and mTOR/p70s6k pathways, PKC pathways, or protein kinase A pathways. The convergence of these pathways via inhibition of GSK-3β on the end effector, the permeability transition pore complex, to limit MPT induction is the general mechanism of cardiomyocyte protection.

Authors

Magdalena Juhaszova, Dmitry B. Zorov, Suhn-Hee Kim, Salvatore Pepe, Qin Fu, Kenneth W. Fishbein, Bruce D. Ziman, Su Wang, Kirsti Ytrehus, Christopher L. Antos, Eric N. Olson, Steven J. Sollott

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Figure 1

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ROS are involved in mitochondrial deterioration during hypoxia/reoxygena...
ROS are involved in mitochondrial deterioration during hypoxia/reoxygenation. (A) Reoxygenation-induced mitochondrial hyperpolarization leads to increased ROS. Mitochondria stained with TMRM (ØΨ, red) and DCF (ROS, green) were laser line-scanned (2 Hz) during hypoxia and the reoxygenation phase. The ROS burst is delayed after reoxygenation and starts at the maximum ØΨ. Mitochondrial hyperpolarization lasts for approximately 2 minutes, followed by loss of ØΨ. (B) ØΨ loss in a significant fraction of mitochondria, caused by hypoxia/reoxygenation. Depolarized mitochondria (red-fluorescence “holes”; bottom panels) are associated with increased ROS (green; bottom left panel). Hypoxic PC or pharmacologic PC (represented by Dz) prevents mitochondrial depolarization, and 5HD accentuates the loss. (C) Cell survival after constant-energy photoexcitation of a 25 ∞ 25 ∝m2 region. The right panels show TMRM-stained cells (red) immediately after, and 1 hour after, irradiation. Survival is inversely related to the fraction of mitochondria (mito) undergoing MPT induction and is improved by ROS scavenger (Trolox), NO donor (SNAP), and Dz and impaired by 5HD. (D) Methodology used to determine the ROS threshold of MPT induction. Mitochondria stained with TMRM (red) were laser line-scanned until MPT induction. The average time required for the standardized photoproduction of ROS to cause MPT induction (tMPT) is taken as the index of the ROS threshold in that cell. (E) Two-hertz line scan of individual isolated cardiac mitochondria. Light transmittance (gray) and TMRM fluorescence (red) are overlaid. The abrupt loss of ØΨ (TMRM) and increase in volume (arrow) are similar to those observed in situ (D). Vertical flickering in the image is an artifact caused by movement of adjacent floating mitochondria.