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Mallajosyula JK, Chinta SJ, Rajagopalan S, Nicholls DG, Andersen JK: Metabolic control analysis in a cellular model of elevated MAO-B: relevance to Parkinson's disease. Neurotox Res. 2009 Oct;16(3):186-93. Epub 2009 Mar 5.
We previously demonstrated that spare respiratory capacity of the TCA cycle enzyme alpha-ketoglutarate dehydrogenase (KGDH) was completely abolished upon increasing levels of MAO-B activity in a dopaminergic cell model system (Kumar et al., J Biol Chem 278:46432-46439, 2003). MAO-B mediated increases in H (2) O (2) also appeared to result in direct oxidative inhibition of both mitochondrial complex I and aconitase. In order to elucidate the contribution that each of these components exerts over metabolic respiratory control as well as the impact of MAO-B elevation on their spare respiratory capacities, we performed metabolic respiratory control analysis. In addition to KGDH, we assessed the activities and substrate-mediated respiration of complex I, pyruvate dehydrogenase (PDH), succinate dehydrogenase (SDH), and mitochondrial aconitase in the absence and presence of complex-specific inhibitors in specific and mixed substrate conditions in mitochondria from our MAO-B elevated cells versus controls. Data from this study indicates that Complex I and KGDH are the most sensitive to inhibition by MAO-B mediated H (2) O (2) generation, and could be instrumental in determining the fate of mitochondrial metabolism in this cellular PD model system. |
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