November 2003 Meeting Announcement, Delaware Valley Mass Spectrometry Discussion Group
- Topic: "Proteomics of Oxidative Stress"
- Speaker:Ian A. Blair, University of Pennsylvania
- Date: Monday, November 10, 2003. 6:30 PM
- Time: Social Hour: 6:30 PM. (Pizza and Beer)
Talk: 7:30 PM.
- Place: Widener University, Webb Room.
Oxidative stress results in the formation of reactive oxygen species (ROS), which can damage cellular macromolecules such as DNA and proteins. DNA and protein damage results directly from ROS, or from ROS-derived lipid-hydroperoxides that break down to form the a,b-unsaturated aldehyde genotoxins, 4-oxo-2-nonenal, 4-hydroxy-2-nonenal, and 4,5-epoxy-2(E)-decenal. Lipid hydroperoxides are also formed enzymatically during oxidative stress from 5-lipoxygenase (5-LOX), 15-LOX, cyclooxygenase-1 (COX-1), and COX-2. Both 15-LOX and COX-2 convert linoleic acid into 13(S)-hydroperoxyoctadecadienoic acid (13-HPODE) the prototypic w-6 polyunsaturated fatty acid (PUFA) hydroperoxide. We have investigated the homolytic decomposition of 13-HPODE with a variety of initiators. These studies characterized 4-hydroperoxy-2-nonenal, 4-oxo-2-nonenal, 4-hydroxy-2-nonenal, and 4,5-epoxy-2-decenal as lipid hydroperoxide-derived bifunctional electrophiles (1). Two quite distinct pathways were involved in their formation. One pathway, which involves the intermediate formation of hydroperoxide-derived alkoxy radicals, results in the formation of 4,5-epoxy-2(E)-decenal through an a-cleavage reaction. The other pathway involves the intermediate formation of the potential genotoxin 4-hydroperoxy-2-nonenal, which then decomposes to 4-oxo-2-nonenal and 4-hydroxy-2-nonenal.
4-Oxo-2-nonenal forms heptanone-etheno-2'-deoxyguanosine (dGuo), heptanone-etheno-2'-deoxyadenosine (dAdo), and heptanone-etheno-2'-deoxycytidine adducts with DNA (2,3); whereas 4,5-epoxy-2(E)-decenal forms unsubstituted etheno-dGuo and etheno-2'-dAdo adducts with DNA (2). This latter observation provides an important link between lipid peroxidation and DNA damage. Unsubstituted etheno-dAdo adducts, which are potent mutagens in mammalian cells, have been detected in human tissue DNA and urine. We made the surprising observation that vitamin C can stimulate the breakdown of lipid hydroperoxides to a,b-unsaturated aldehyde genotoxins (1). Using LC/electrospray (ESI)/MS/MS and matrix-assisted laser desorption/ionization/time of flight (MALDI/TOF)/MS and MALDI/TOF/MS/MS we have begun to systematically characterize the lesions that can also occur in proteins. Functional studies have focused on histone proteins because of the possibility that lipid hydroperoxide-mediated epigenetic effects may be induced during oxidative stress. Using a combination of deuterium isotope labeling and LC/MS/MS, it was demonstrated lipid hydroperoxides caused the formation of a cyclic peptide on the HAK motif of histone H4. Current experiments are directed at demonstrating whether this modification can occur on histone proteins during oxidative stress in vivo.
Supported by NIH RO-1 CA95586 and RO-1 CA91016.
1. Lee SH, Oe T, Blair IA. Science. 2001;292:2083-6.
2. Lee SH, Oe T, Blair IA. Chem Res Toxicol. 2002;15:300-4.
3. Pollack M, Oe T, Lee SH, Silva Elipe MV, Arison BH, Blair IA. Chem Res Toxicol. 2003;16:893-900.
- Bio: Dr. Blair received his Ph.D. in Organic Chemistry from Imperial College of Science and Technology, London, where he worked under the direction of the Nobel Laureate Sir Derek H.R. Barton. He then moved to Makerere University, Uganda, under the auspices of the British Council's aid scheme to East Africa. Dr. Blair subsequently moved to Australia where he held research fellowships at Adelaide University and the Australian National University in Canberra. In 1979, Dr. Blair was appointed to a lectureship and then senior lectureship in the Department of Clinical Pharmacology at the Royal Postgraduate Medical School (now part of Imperial College of Science, Technology, and Medicine), University of London. He left the Royal Postgraduate Medical School in 1983 and was appointed as a Professor in the Department of Pharmacology, at Vanderbilt University in Nashville, TN. He was also appointed as a Professor of Chemistry. In 1996, Dr. Blair was appointed to the Derek H.R. Barton Chair in Pharmacology at Vanderbilt University in recognition of his contributions to the fields of pharmacogenetics, drug metabolism, and analytical pharmacology. He was recruited to the University of Pennsylvania in January 1997 to an endowed chair as the A.N. Richards Professor of Pharmacology in order to set up a new Center for Cancer Pharmacology. The Center was officially established in June of 1997 with Dr. Blair as its first Director. There are currently some 40 investigators within the Center together with an associated NIH-funded graduate student program. Dr. Blair is an internationally renowned expert in the use of mass spectrometric methods for the quantitation and elucidation of structures of endogenous biomolecules, DNA-adducts, protein adducts, drugs and their metabolites. Dr. Blair has published 190 research articles in leading journals. He is on the editorial board of Chemical Research in Toxicology, Journal of Mass Spectrometry, and Current Drug Metabolism and regularly serves on NIH study sections. He was recently appointed as the Vice-Chair of the Department of Pharmacology and as a Professor of Chemistry in the School of Arts and Sciences. He is also Scientific Director for the recently established Proteomics Facility in the Genomics Institute at the University of Pennsylvania.
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