Mitochondrial DNA depletion by ethidium bromide decreases neuronal mitochondrial creatine kinase: Implications for striatal energy metabolism

• Published in: PloS one Vol. 12; no. 12; p. e0190456
• Main Authors: Warren, Emily Booth, Aicher, Aidan Edward, Fessel, Joshua Patrick, Konradi, Christine
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 29.12.2017; Public Library of Science (PLoS)
• Subjects: Amino acids; Animals; Astrocytes; Bioenergetics; Biology and life sciences; Cancer; Cell cycle; Cells, Cultured; Corpus Striatum - metabolism; Creatine; Creatine kinase; Creatine Kinase - metabolism; Deoxyribonucleic acid; Depletion; Development and progression; Dihydroxyphenylalanine; DNA; DNA damage; DNA methylation; DNA, Mitochondrial - metabolism; Dyskinesia; Electron transport; Energy Metabolism; Ethidium - pharmacology; Ethidium bromide; Gene expression; Genetic aspects; Genomes; Glycolysis; Humans; Kinases; Levodopa; Medicine and Health Sciences; Metabolism; Mitochondria; Mitochondria - enzymology; Mitochondrial DNA; Movement disorders; Neostriatum; Nervous system diseases; Neurodegenerative diseases; Neurons; Oxygen; Oxygen Consumption; Parkinson's disease; Patients; Pharmacology; Phosphocreatine; Phosphorylation; Physical Sciences; Physiological aspects; Proteins; Putamen; Rats; Rats, Sprague-Dawley; Transcription; United States; United States > US; Tennessee; Nashville Tennessee
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0190456

Mitochondrial DNA (mtDNA), the discrete genome which encodes subunits of the mitochondrial respiratory chain, is present at highly variable copy numbers across cell types. Though severe mtDNA depletion dramatically reduces mitochondrial function, the impact of tissue-specific mtDNA reduction remains debated. Previously, our lab identified reduced mtDNA quantity in the putamen of Parkinson's Disease (PD) patients who had developed L-DOPA Induced Dyskinesia (LID), compared to PD patients who had not developed LID and healthy subjects. Here, we present the consequences of mtDNA depletion by ethidium bromide (EtBr) treatment on the bioenergetic function of primary cultured neurons, astrocytes and neuron-enriched cocultures from rat striatum. We report that EtBr inhibition of mtDNA replication and transcription consistently reduces mitochondrial oxygen consumption, and that neurons are significantly more sensitive to EtBr than astrocytes. EtBr also increases glycolytic activity in astrocytes, whereas in neurons it reduces the expression of mitochondrial creatine kinase mRNA and levels of phosphocreatine. Further, we show that mitochondrial creatine kinase mRNA is similarly downregulated in dyskinetic PD patients, compared to both non-dyskinetic PD patients and healthy subjects. Our data support a hypothesis that reduced striatal mtDNA contributes to energetic dysregulation in the dyskinetic striatum by destabilizing the energy buffering system of the phosphocreatine/creatine shuttle.