title: Cell-permeable peptide antioxidants targeted to inner mitochondrial membrane inhibit mitochondrial swelling, oxidative cell death, and reperfusion injury.
abstract: Reactive oxygen species (ROS) play a key role in promoting mitochondrial cytochrome c release and induction of apoptosis. ROS induce dissociation of cytochrome c from cardiolipin on the inner mitochondrial membrane (IMM), and cytochrome c may then be released via mitochondrial permeability transition (MPT)-dependent or MPT-independent mechanisms. We have developed peptide antioxidants that target the IMM, and we used them to investigate the role of ROS and MPT in cell death caused by t-butylhydroperoxide (tBHP) and 3-nitropropionic acid (3NP). The structural motif of these peptides centers on alternating aromatic and basic amino acid residues, with dimethyltyrosine providing scavenging properties. These peptide antioxidants are cell-permeable and concentrate 1000-fold in the IMM. They potently reduced intracellular ROS and cell death caused by tBHP in neuronal N(2)A cells (EC(50) in nm range). They also decreased mitochondrial ROS production, inhibited MPT and swelling, and prevented cytochrome c release induced by Ca(2+) in isolated mitochondria. In addition, they inhibited 3NP-induced MPT in isolated mitochondria and prevented mitochondrial depolarization in cells treated with 3NP. ROS and MPT have been implicated in myocardial stunning associated with reperfusion in ischemic hearts, and these peptide antioxidants potently improved contractile force in an ex vivo heart model. It is noteworthy that peptide analogs without dimethyltyrosine did not inhibit mitochondrial ROS generation or swelling and failed to prevent myocardial stunning. These results clearly demonstrate that overproduction of ROS underlies the cellular toxicity of tBHP and 3NP, and ROS mediate cytochrome c release via MPT. These IMM-targeted antioxidants may be very beneficial in the treatment of aging and diseases associated with oxidative stress.
authors.affiliation: Departments of Pharmacology and Biochemistry, Joan and Sanford I. Weill Medical College of Cornell University, New York, NY 10021, USA.
authors.forename: Kesheng
authors.initials: K
authors.lastname: Zhao
authors.forename: Guo-Min
authors.initials: GM
authors.lastname: Zhao
authors.forename: Dunli
authors.initials: D
authors.lastname: Wu
authors.forename: Yi
authors.initials: Y
authors.lastname: Soong
authors.forename: Alex V
authors.initials: AV
authors.lastname: Birk
authors.forename: Peter W
authors.initials: PW
authors.lastname: Schiller
authors.forename: Hazel H
authors.initials: HH
authors.lastname: Szeto
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology*; D018938:Caco-2 Cells; D002118:Calcium / Q000378:metabolism; D002308:Cardiolipins / Q000378:metabolism; D016923:Cell Death; D002470:Cell Survival; D045304:Cytochromes c / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism*; D008099:Liver / Q000378:metabolism; D008297:Male; D051379:Mice; D008928:Mitochondria / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000378:metabolism; D009574:Nitro Compounds; D018384:Oxidative Stress; D010100:Oxygen / Q000378:metabolism; D010101:Oxygen Consumption; D010455:Peptides / Q000737:chemistry*; D011422:Propionates / Q000737:chemistry; D017382:Reactive Oxygen Species; D015424:Reperfusion; D015427:Reperfusion Injury; D013997:Time Factors; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000737:chemistry; D020122:tert-Butylhydroperoxide / Q000737:chemistry
chemical_list: D000975:Antioxidants; D002308:Cardiolipins; D009574:Nitro Compounds; D010455:Peptides; D011422:Propionates; D017382:Reactive Oxygen Species; C076121:2',6'-dimethyltyrosine; D014443:Tyrosine; D045304:Cytochromes c; D020122:tert-Butylhydroperoxide; D006861:Hydrogen Peroxide; C015392:3-nitropropionic acid; D010100:Oxygen; D002118:Calcium