1504, either, cat.26
THE ALTERATION OF THE BIOENERGETIC PATHWAY AGGRAVATES ATHEROSCLEROSIS IN PARAOXONASE-2 DEFICIENCY MICE.
A. Devarajan1, N. Bourquard1,2, S. Morvardi3, C. Clarke3, V. Grijalva1,
D. Meriwether III4, J.F. Teiber6, L. Vergnes5, K. Reue5, S.T. Reddy1,2
1Department of Medicine/Cardiology, 2Department of Molecular and Medical Pharmacology, 3Department of Chemistry and Biochemistry, 4Department of Obstetrics and Gynecology, 5Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA ,6Department of Internal Medicine, Division of Epidemiology, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
Objective: Reactive oxygen species are produced in the mitochondria by the oxidative phosphorylation involved in energy production, a process that is mediated by coenzyme Q10. We have reported that Paraoxonase (PON2) is localized in the mitochondria and that PON2 deficiency (PON2-def) aggravates oxidative stress and leads to atherosclerosis. Previous reports from x-ray crystallography studies suggest that fatty acid tail side chains, like those associated with coenzyme Q10, fit into the substrate pocket of paraoxonase. Here, we sought to determine whether PON2 binds coenzyme Q10 in vitro and studied its significance in vivo.
Methods and Results: We report for the first time, using surface plasmon resonance on a BIAcore 3000 system, that recombinant PON2 binds coenzyme Q10 in the presence of calcium with kD of 4.4 X 10-8 M. We found that oxygen consumption rate was significantly lowered (250 ± 20 pico mole/per min) in the peritoneal macrophage of PON2-def/apoE-/- mice compared to control (330 ± 30 pico mole/per min). This decreased oxygen consumption correlated significantly with decreased ATP and increased superoxide level. Furthermore, mitochondrial aconitase activity was two fold lower in PON2-def/apoE-/- mice compared to control mice, despite any changes in aconitase protein expression level. Finally, the aortas of PON2-def/apoE-/- mice have significantly increased (p<0.05) superoxide levels relative to aortas from control mice.
Conclusion: PON2 binds coenzyme Q10 and defciency of PON2 alters the bioenergetic pathway and antioxidant status in the mitochondria in a manner that would trigger atherosclerosis.