title: Autophagy protects against aminochrome-induced cell death in substantia nigra-derived cell line.
abstract: Aminochrome, the precursor of neuromelanin, has been proposed to be involved in the neurodegeneration neuromelanin-containing dopaminergic neurons in Parkinson's disease. We aimed to study the mechanism of aminochrome-dependent cell death in a cell line derived from rat substantia nigra. We found that aminochrome (50μM), in the presence of NAD(P)H-quinone oxidoreductase, EC 1.6.99.2 (DT)-diaphorase inhibitor dicoumarol (DIC) (100μM), induces significant cell death (62 ± 3%; p < 0.01), increase in caspase-3 activation (p < 0.001), release of cytochrome C, disruption of mitochondrial membrane potential (p < 0.01), damage of mitochondrial DNA, damage of mitochondria determined with transmission electron microscopy, a dramatic morphological change characterized as cell shrinkage, and significant increase in number of autophagic vacuoles. To determine the role of autophagy on aminochrome-induced cell death, we incubated the cells in the presence of vinblastine and rapamycin. Interestingly, 10μM vinblastine induces a 5.9-fold (p < 0.001) and twofold (p < 0.01) significant increase in cell death when the cells were incubated with 30μM aminochrome in the absence and presence of DIC, respectively, whereas 10μM rapamycin preincubated 24 h before addition of 50μM aminochrome in the absence and the presence of 100μM DIC induces a significant decrease (p < 0.001) in cell death. In conclusion, autophagy seems to be an important protective mechanism against two different aminochrome-induced cell deaths that initially showed apoptotic features. The cell death induced by aminochrome when DT-diaphorase is inhibited requires activation of mitochondrial pathway, whereas the cell death induced by aminochrome alone requires inhibition of autophagy-dependent degrading of damaged organelles and recycling through lysosomes.
authors.affiliation: Program of Molecular and Clinical Pharmacology, Biomedical Science Institute, Faculty of Medicine, University of Chile, Santiago 8380453, Chile.
authors.forename: Irmgard
authors.initials: I
authors.lastname: Paris
authors.forename: Patricia
authors.initials: P
authors.lastname: Muñoz
authors.forename: Sandro
authors.initials: S
authors.lastname: Huenchuguala
authors.forename: Eduardo
authors.initials: E
authors.lastname: Couve
authors.forename: Laurie H
authors.initials: LH
authors.lastname: Sanders
authors.forename: John Timothy
authors.initials: JT
authors.lastname: Greenamyre
authors.forename: Pablo
authors.initials: P
authors.lastname: Caviedes
authors.forename: Juan
authors.initials: J
authors.lastname: Segura-Aguilar
mesh_terms: D000818:Animals; D001343:Autophagy / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects*; D002460:Cell Line; D045304:Cytochromes c / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000378:metabolism; D045563:Indolequinones / Q000633:toxicity*; D008543:Melanins / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000378:metabolism; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000037:antagonists & inhibitors; D009410:Nerve Degeneration / Q000378:metabolism; D051381:Rats; D020123:Sirolimus / Q000494:pharmacology; D013378:Substantia Nigra / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D014747:Vinblastine / Q000494:pharmacology
chemical_list: D004272:DNA, Mitochondrial; D045563:Indolequinones; D008543:Melanins; C014121:neuromelanin; C091584:aminochrome 1; D014747:Vinblastine; D045304:Cytochromes c; D016660:NAD(P)H Dehydrogenase (Quinone); C505410:Casp3 protein, rat; D053148:Caspase 3; D020123:Sirolimus