Superoxide activates uncoupling proteins by generating carbon-centered radicals and initiating lipid peroxidation: studies using a mitochondria-targeted spin trap derived from alpha-phenyl-N-tert-butylnitrone.

TitleSuperoxide activates uncoupling proteins by generating carbon-centered radicals and initiating lipid peroxidation: studies using a mitochondria-targeted spin trap derived from alpha-phenyl-N-tert-butylnitrone.
Publication TypeJournal Article
Year of Publication2003
AuthorsMurphy, MP, Echtay, KS, Blaikie, FH, Asin-Cayuela, J, Cochemé, HM, Green, K, Buckingham, JA, Taylor, ER, Hurrell, F, Hughes, G, Miwa, S, Cooper, CE, Svistunenko, DA, Smith, RAJ, Brand, MD
JournalJ Biol Chem
Volume278
Issue49
Pagination48534-45
Date Published2003 Dec 05
ISSN0021-9258
KeywordsAnimals, Carbon, Carrier Proteins, Cyclic N-Oxides, Electron Spin Resonance Spectroscopy, Free Radicals, Ion Channels, Lipid Peroxidation, Membrane Proteins, Mitochondria, Liver, Mitochondrial Proteins, Nitrogen Oxides, Rats, Reactive Oxygen Species, Spin Labels, Superoxides, Uncoupling Protein 1
Abstract

Although the physiological role of uncoupling proteins (UCPs) 2 and 3 is uncertain, their activation by superoxide and by lipid peroxidation products suggest that UCPs are central to the mitochondrial response to reactive oxygen species. We examined whether superoxide and lipid peroxidation products such as 4-hydroxy-2-trans-nonenal act independently to activate UCPs, or if they share a common pathway, perhaps by superoxide exposure leading to the formation of lipid peroxidation products. This possibility can be tested by blocking the putative reactive oxygen species cascade with selective antioxidants and then reactivating UCPs with distal cascade components. We synthesized a mitochondria-targeted derivative of the spin trap alpha-phenyl-N-tert-butylnitrone, which reacts rapidly with carbon-centered radicals but is unreactive with superoxide and lipid peroxidation products. [4-[4-[[(1,1-Dimethylethyl)-oxidoimino]methyl]phenoxy]butyl]triphenylphosphonium bromide (MitoPBN) prevented the activation of UCPs by superoxide but did not block activation by hydroxynonenal. This was not due to MitoPBN reacting with superoxide or the hydroxyl radical or by acting as a chain-breaking antioxidant. MitoPBN did react with carbon-centered radicals and also prevented lipid peroxidation by the carbon-centered radical generator 2,2'-azobis(2-methyl propionamidine) dihydrochloride (AAPH). Furthermore, AAPH activated UCPs, and this was blocked by MitoPBN. These data suggest that superoxide and lipid peroxidation products share a common pathway for the activation of UCPs. Superoxide releases iron from iron-sulfur center proteins, which then generates carbon-centered radicals that initiate lipid peroxidation, yielding breakdown products that activate UCPs.

DOI10.1074/jbc.M308529200
Alternate JournalJ. Biol. Chem.
Citation Key10.1074/jbc.M308529200
PubMed ID12972420