title: Rotenone upregulates alpha-synuclein and myocyte enhancer factor 2D independently from lysosomal degradation inhibition.
abstract: Dysfunctions of chaperone-mediated autophagy (CMA), the main catabolic pathway for alpha-synuclein, have been linked to the pathogenesis of Parkinson's disease (PD). Since till now there is limited information on how PD-related toxins may affect CMA, in this study we explored the effect of mitochondrial complex I inhibitor rotenone on CMA substrates, alpha-synuclein and MEF2D, and effectors, lamp2A and hsc70, in a human dopaminergic neuroblastoma SH-SY5Y cell line. Rotenone induced an upregulation of alpha-synuclein and MEF2D protein levels through the stimulation of their de novo synthesis rather than through a reduction of their CMA-mediated degradation. Moreover, increased MEF2D transcription resulted in higher nuclear protein levels that exert a protective role against mitochondrial dysfunction and oxidative stress. These results were compared with those obtained after lysosome inhibition with ammonium chloride. As expected, this toxin induced the cytosolic accumulation of both alpha-synuclein and MEF2D proteins, as the result of the inhibition of their lysosome-mediated degradation, while, differently from rotenone, ammonium chloride decreased MEF2D nuclear levels through the downregulation of its transcription, thus reducing its protective function. These results highlight that rotenone affects alpha-synuclein and MEF2D protein levels through a mechanism independent from lysosomal degradation inhibition.
authors.affiliation: Laboratory of Neurobiology, Department of Surgery and Interdisciplinary Medicine, University of Milano-Bicocca, Via Cadore 48, 20900 Monza, Italy. gessica.sala@unimib.it
authors.forename: Gessica
authors.initials: G
authors.lastname: Sala
authors.forename: Alessandro
authors.initials: A
authors.lastname: Arosio
authors.forename: Giovanni
authors.initials: G
authors.lastname: Stefanoni
authors.forename: Laura
authors.initials: L
authors.lastname: Melchionda
authors.forename: Chiara
authors.initials: C
authors.lastname: Riva
authors.forename: Daniele
authors.initials: D
authors.lastname: Marinig
authors.forename: Laura
authors.initials: L
authors.lastname: Brighina
authors.forename: Carlo
authors.initials: C
authors.lastname: Ferrarese
mesh_terms: D000643:Ammonium Chloride / Q000494:pharmacology; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D000071186:Beclin-1; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D050883:HSC70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D052119:Lysosomal-Associated Membrane Protein 2 / Q000235:genetics / Q000378:metabolism; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism*; D064326:MEF2 Transcription Factors / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D010588:Phagosomes / Q000187:drug effects / Q000378:metabolism; D059748:Proteolysis / Q000187:drug effects*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012402:Rotenone / Q000633:toxicity*; D014158:Transcription, Genetic / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects*; D051844:alpha-Synuclein / Q000235:genetics* / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; C491997:BECN1 protein, human; D000071186:Beclin-1; D050883:HSC70 Heat-Shock Proteins; C494371:HSPA8 protein, human; C497811:LAMP2 protein, human; D052119:Lysosomal-Associated Membrane Protein 2; C477012:MAP1LC3A protein, human; D064326:MEF2 Transcription Factors; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; D012333:RNA, Messenger; D051844:alpha-Synuclein; D000643:Ammonium Chloride; D012402:Rotenone