Metabolic control analysis in a cellular model of elevated MAO-B: relevance to Parkinson's disease.
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.
Mallajosyula
Jyothi K
JK
Buck Institute for Age Research, Novato, CA 94945, USA.
Chinta
Shankar J
SJ
Rajagopalan
Subramanian
S
Nicholls
David G
DG
Andersen
Julie K
JK
D000154:Aconitate Hydratase / Q000378:metabolism; D000818:Animals; D019069:Cell Respiration / Q000187:drug effects / Q000502:physiology; D004318:Doxycycline / Q000494:pharmacology; D042967:Electron Transport Complex I / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007306:Insecticides / Q000494:pharmacology; D007655:Ketoglutarate Dehydrogenase Complex / Q000378:metabolism; D007658:Ketone Oxidoreductases / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology*; D008995:Monoamine Oxidase / Q000378:metabolism*; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D016716:PC12 Cells / Q000187:drug effects / Q000201:enzymology; D011808:Quinone Reductases; D051381:Rats; D012402:Rotenone / Q000494:pharmacology; D013385:Succinate Dehydrogenase / Q000378:metabolism
D007306:Insecticides; D016877:Oxidants; D012402:Rotenone; D006861:Hydrogen Peroxide; D007658:Ketone Oxidoreductases; C053164:pyruvate dehydrogenase (NADP+); D007655:Ketoglutarate Dehydrogenase Complex; D013385:Succinate Dehydrogenase; D008995:Monoamine Oxidase; D009247:NADH, NADPH Oxidoreductases; D011808:Quinone Reductases; C033633:dichlorophenolindophenol reductase; D000154:Aconitate Hydratase; D042967:Electron Transport Complex I; D004318:Doxycycline