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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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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GSK-3β, and not GSK-3α, regulates the protection state. (A) SiRNA treatm...
GSK-3β, and not GSK-3α, regulates the protection state. (A) SiRNA treatment specifically decreases respective protein levels of GSK-3α and GSK-3β in neonatal rat cardiac myocytes; GFP siRNA and media alone served as negative controls. Immunoblot of cell lysates probed with antibodies against GSK-3α/β, GSK-3β, and 39-kDa subunit of mitochondrial Complex I (as a loading control). The immunoblot is representative of two independent experiments. (B) Silencing of GSK-3β, but not of GSK-3α, enhances tMPT to levels comparable to insulin-induced protection in neonatal rat cardiac myocytes. Data comprise two independent experiments; n = 30 in each group (except n = 22 for GFP siRNA). *P < 0.02, **P < 0.001, ***P < 0.0001 vs. respective control. (C) Constitutive activation of GSK-3β prevents ability to engage protective signaling. GSK-3β inhibition is required for protection against oxidative stress. Both mitochondrial sweller_dependent and _independent protection mechanisms are abolished in adult cardiac myocytes from GSK-3β S9A TG mice. *P < 0.02 vs. control. (D) Hypoxic PC protection after hypoxia/reoxygenation is abolished in adult cardiac myocytes from GSK-3β S9A TG mice. #P < 0.01 vs. control.