title: JNK inhibition of VMAT2 contributes to rotenone-induced oxidative stress and dopamine neuron death.
abstract: Treatment with rotenone, both in vitro and in vivo, is widely used to model dopamine neuron death in Parkinson's disease upon exposure to environmental neurotoxicants and pesticides. Mechanisms underlying rotenone neurotoxicity are still being defined. Our recent studies suggest that rotenone-induced dopamine neuron death involves microtubule destabilization, which leads to accumulation of cytosolic dopamine and consequently reactive oxygen species (ROS). Furthermore, the c-Jun N-terminal protein kinase (JNK) is required for rotenone-induced dopamine neuron death. Here we report that the neural specific JNK3 isoform of the JNKs, but not JNK1 or JNK2, is responsible for this neuron death in primary cultured dopamine neurons. Treatment with taxol, a microtubule stabilizing agent, attenuates rotenone-induced phosphorylation and presumably activation of JNK. This suggests that JNK is activated by microtubule destabilization upon rotenone exposure. Moreover, rotenone inhibits VMAT2 activity but not VMAT2 protein levels. Significantly, treatment with SP600125, a pharmacological inhibitor of JNKs, attenuates rotenone inhibition of VMAT2. Furthermore, decreased VMAT2 activity following in vitro incubation of recombinant JNK3 protein with purified mesencephalic synaptic vesicles suggests that JNK3 can inhibit VMAT2 activity. Together with our previous findings, these results suggest that rotenone induces dopamine neuron death through a series of sequential events including microtubule destabilization, JNK3 activation, VMAT2 inhibition, accumulation of cytosolic dopamine, and generation of ROS. Our data identify JNK3 as a novel regulator of VMAT2 activity.
authors.affiliation: School of Biological Sciences and Technology, College of Natural Sciences, College of Medicine, Chonnam National University, Gwangju 500-757, South Korea; Toxicology Program in the Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98195, United States. Electronic address: choiw@chonnam.ac.kr.
authors.forename: Won-Seok
authors.initials: WS
authors.lastname: Choi
authors.affiliation: College of Life Sciences, Sejong University, Seoul 143-747, South Korea; Toxicology Program in the Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98195, United States. Electronic address: kimhyung@sejong.ac.kr.
authors.forename: Hyung-Wook
authors.initials: HW
authors.lastname: Kim
authors.affiliation: Toxicology Program in the Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98195, United States. Electronic address: zxia@u.washington.edu.
authors.forename: Zhengui
authors.initials: Z
authors.lastname: Xia
mesh_terms: D000818:Animals; D053148:Caspase 3 / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D059290:Dopaminergic Neurons / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D004789:Enzyme Activation; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008870:Microtubules / Q000187:drug effects / Q000201:enzymology; D048057:Mitogen-Activated Protein Kinase 10 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects*; D034622:RNA Interference; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D012402:Rotenone / Q000633:toxicity*; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014162:Transfection; D050493:Vesicular Monoamine Transport Proteins / Q000378:metabolism*
chemical_list: D017382:Reactive Oxygen Species; C493453:Slc18a2 protein, mouse; C493454:Slc18a2 protein, rat; D050493:Vesicular Monoamine Transport Proteins; D012402:Rotenone; D048057:Mitogen-Activated Protein Kinase 10; C505409:Casp3 protein, mouse; C505410:Casp3 protein, rat; D053148:Caspase 3
keywords: Dopamine neuron; JNK; Microtubule; Parkinson’s disease; Rotenone; VMAT2