Abstract
Progress in mass spectroscopy of posttranslational oxidative modifications has enabled researchers to experimentally verify the concept of redox signaling. We focus here on redox signaling originating from mitochondria under physiological situations, discussing mechanisms of transient redox burst in mitochondria, as well as the possible ways to transfer such redox signals to specific extramitochondrial targets. A role of peroxiredoxins is described which enables redox relay to other targets. Examples of mitochondrial redox signaling are discussed: initiation of hypoxia-inducible factor (HIF) responses; retrograde redox signaling to PGC1α during exercise in skeletal muscle; redox signaling in innate immune cells; redox stimulation of insulin secretion, and other physiological situations.
Highlights
Progress in mass spectroscopy of posttranslational oxidative modifications has enabled researchers to experimentally verify the concept of redox signaling
Examples of the most studied physiological redox signaling from mitochondria are (1) initiation of hypoxia-inducible factor (HIF) and consequent transcriptome reprogramming; (2) retrograde redox signaling to proliferator-activated receptor-gamma coactivator-1α (PGC1α) during exercise in skeletal muscle; (3) redox signaling in innate immune cells; (4) redox stimulation of insulin secretion due to metabolism of secretagogues such as branched-chain keto acids and fatty acids; and other situations, which we attempt to describe in this review
Oxygen sensing in cells is provided by multiple mechanisms, among which central mechanism lies in action of 2OG-dependent prolyl hydroxylases (PHDs), alternatively termed Egl nine homolog
Summary
Excellent reviews can be recommended to recall mechanisms of superoxide generation within the respiratory chain complexes, and by several mitochondrial dehydrogenases, as well as electron-transfer flavoprotein: coenzyme Q oxidoreductase (ETFQOR) [10,11,12,13]. Ion channels typically receive cell signals from three distinct sources through the following: (i) cytosolic Ca2+ elevation; (ii) phosphorylation by Ca2+ - and/or redox-dependent kinases, either cytosolic ones or those recruited to the mitochondrial matrix or ICS; (iii) other oxidative post-translational modifications dependent directly on cytosolic ROS; and, hypothetically (iv) other post-translational modifications such as acetylation, acylation, etc. If sustained cytosolic Ca2+ concentration elevation occurs, the Ca2+ concentration triggers an excessive mitochondrial Ca2+ uptake called mitochondrial Ca2+ overload This is followed by ∆Ψm depolarization, decreased ATP production, and, most notably, by an acceleration of superoxide generation, leading to activation of cell death pathways under various pathological conditions [46]. The phosphorylation of the mitochondrial K+ channels during ischemic preconditioning seems to be a key mechanism in cardioprotection [73]
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