H(2)O(2)-mediated modulation of cytosolic signaling and organelle function in rat hippocampus.
Reactive oxygen species (ROS) released from (dys-)functioning mitochondria contribute to normal and pathophysiological cellular signaling by modulating cytosolic redox state and redox-sensitive proteins. To identify putative redox targets involved in such signaling, we exposed hippocampal neurons to hydrogen peroxide (H(2)O(2)). Redox-sensitive dyes indicated that externally applied H(2)O(2) may oxidize intracellular targets in cell cultures and acute tissue slices. In cultured neurons, H(2)O(2) (EC(50) 118 microM) induced an intracellular Ca(2+) rise which could still be evoked upon Ca(2+) withdrawal and mitochondrial uncoupling. It was, however, antagonized by thapsigargin, dantrolene, 2-aminoethoxydiphenyl borate, and high levels of ryanodine, which identifies the endoplasmic reticulum (ER) as the intracellular Ca(2+) store involved. Intracellular accumulation of endogenously generated H(2)O(2)-provoked by inhibiting glutathione peroxidase-also released Ca(2+) from the ER, as did extracellular generation of superoxide. Phospholipase C (PLC)-mediated metabotropic signaling was depressed in the presence of H(2)O(2), but cytosolic cyclic adenosine-5'-monophosphate (cAMP) levels were not affected. H(2)O(2) (0.2-5 mM) moderately depolarized mitochondria, halted their intracellular trafficking in a Ca(2+)- and cAMP-independent manner, and directly oxidized cellular nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FADH(2)). In part, the mitochondrial depolarization reflects uptake of Ca(2+) previously released from the ER. We conclude that H(2)O(2) releases Ca(2+) from the ER via both ryanodine and inositol trisphosphate receptors. Mitochondrial function is not markedly impaired even by millimolar concentrations of H(2)O(2). Such modulation of Ca(2+) signaling and organelle interaction by ROS affects the efficacy of PLC-mediated metabotropic signaling and may contribute to the adjustment of neuronal function to redox conditions and metabolic supply.
DFG Research Center Molecular Physiology of the Brain (CMPB), Zentrum für Physiologie und Pathophysiologie, Abteilung Neuro- und Sinnesphysiologie, Georg-August-Universität Göttingen, Humboldtallee 23, 37073, Göttingen, Germany.
Florian J
FJ
Gerich
Frank
F
Funke
Belinda
B
Hildebrandt
Martin
M
Fasshauer
Michael
M
Müller
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001370:Axonal Transport / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D005182:Flavin-Adenine Dinucleotide / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism* / Q000494:pharmacology; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000037:antagonists & inhibitors; D007700:Kinetics; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009068:Movement / Q000187:drug effects; D009243:NAD / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D015388:Organelles / Q000187:drug effects / Q000502:physiology*; D010084:Oxidation-Reduction / Q000187:drug effects; D058910:Purinergic P2 Receptor Agonists; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D018048:Receptors, Purinergic P2; D058925:Receptors, Purinergic P2Y12
D002121:Calcium Channel Blockers; D053496:Inositol 1,4,5-Trisphosphate Receptors; C553058:P2ry12 protein, rat; D058910:Purinergic P2 Receptor Agonists; D017382:Reactive Oxygen Species; D018048:Receptors, Purinergic P2; D058925:Receptors, Purinergic P2Y12; D009243:NAD; D005182:Flavin-Adenine Dinucleotide; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide