Dopamine transporter-mediated cytotoxicity of 6-hydroxydopamine in vitro depends on expression of mutant α-synucleins related to Parkinson's disease

• Published in: Neurochemistry international Vol. 48; no. 5; pp. 329 - 340
• Main Authors: Lehmensiek, Vera, Tan, Eva-Maria, Liebau, Stefan, Lenk, Thomas, Zettlmeisl, Heinz, Schwarz, Johannes, Storch, Alexander
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.04.2006; Elsevier
• Subjects: 6-Hydroxydopamine; Adenosine Triphosphate - metabolism; alpha-Synuclein - genetics; alpha-Synuclein - metabolism; Biological and medical sciences; Cell Line; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Dopamine - metabolism; Dopamine Plasma Membrane Transport Proteins - drug effects; Dopamine Plasma Membrane Transport Proteins - metabolism; Dopamine transporter; Dose-Response Relationship, Drug; Energy Metabolism - drug effects; Energy Metabolism - physiology; Fundamental and applied biological sciences. Psychology; Humans; Medical sciences; Mitochondria - drug effects; Mitochondria - metabolism; Mitochondrial dysfunction; Mutation - genetics; Neurology; Neurons - drug effects; Neurons - metabolism; Neurotoxins - toxicity; Oxidative Stress - drug effects; Oxidative Stress - physiology; Oxidopamine - toxicity; Parkinson Disease - metabolism; Parkinson Disease - physiopathology; Parkinson's disease; Protein Isoforms - drug effects; Protein Isoforms - metabolism; Sympatholytics - toxicity; Vertebrates: nervous system and sense organs; α-Synuclein; α-Synuclein; Mitochondrial dysfunction; Parkinson's disease; DAT; HEK-hDAT; 6-Hydroxydopamine; HEK-293; 6-OHDA; Dopamine transporter; GBR12909; MPP; wt; Nervous system diseases; Dopamine; Parkinson disease; Cytotoxicity; Catecholamine; Oxidopamine; In vitro; Cerebral disorder; Mitochondria; Central nervous system disease; Neurotransmitter; Degenerative disease; Mutation; Carrier protein; α-synuclein; Extrapyramidal syndrome
• ISSN: 0197-0186; 1872-9754
• DOI: 10.1016/j.neuint.2005.11.008

6-Hydroxydopamine (6-OHDA) is widely used to produce animal models of Parkinson's disease (PD) by selectively destroying the nigro-striatal dopaminergic systems, but selective toxicity of 6-OHDA towards dopaminergic cells in vitro remains controversial. Mutant (A30P and A53T) α-synuclein isoforms cause increased vulnerability of cells towards various toxic insults and enhance dopamine transporter (DAT)-mediated toxicity of the selective dopaminergic neurotoxin and mitochondrial complex I inhibitor MPP + in vitro. Here we extend our recent studies on DAT-mediated toxicity to elucidate the mechanisms involved in selective dopaminergic toxicity of 6-OHDA. We studied the cytotoxicity as well as the toxic mechanisms of 6-OHDA in human embryonic kidney HEK-293 cells ectopically co-expressing mutant α-synucleins and the human DAT protein. 6-OHDA showed half-maximal toxic concentration (TC 50) of 88 μM in HEK-hDAT cells without α-synuclein expression after 24 h, whereas the TC 50 values significantly decreased to 58 and 39 μM by expression of A30P and A53T α-synuclein, respectively. α-Synuclein expression did not affect 6-OHDA toxicity in HEK-293 cells not expressing the DAT. Analysis of intracellular parameters of cellular energy metabolism revealed that the co-expression of mutant α-synucleins in HEK-hDAT cells accelerates the reduction of intracellular net ATP levels and ATP/ADP ratios induced by 6-OHDA. Uptake function of the DAT was not altered by expression of α-synuclein isoforms. Our data suggest a mechanism of 6-OHDA-induced dopaminergic toxicity involving an interaction of mutant α-synucleins with the DAT molecule and subsequent acceleration of cellular energy depletion that might be relevant for the pathogenesis of PD.