Silencing DJ-1 reveals its contribution in paraquat-induced autophagy

• Published in: Journal of neurochemistry 2009-05, Vol.109 (3), p.889-898
• Main Authors: González-Polo, Rosa A, Niso-Santano, Mireia, Morán, José M, Ortiz-Ortiz, Miguel A, Bravo-San Pedro, José M, Soler, Germán, Fuentes, José M
• Format: Article
• Language: English
• Subjects: Aging; Analysis of Variance; Annexin A5 - metabolism; apoptosis; autophagy; Autophagy - drug effects; Autophagy - physiology; Biochemistry; Biological and medical sciences; Cell Line, Tumor; Cellular biology; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; DJ-1; Dose-Response Relationship, Drug; Down-Regulation - drug effects; Flow Cytometry - methods; Herbicides - pharmacology; Humans; Intracellular Signaling Peptides and Proteins - antagonists & inhibitors; Intracellular Signaling Peptides and Proteins - genetics; Intracellular Signaling Peptides and Proteins - metabolism; Medical sciences; Microtubule-Associated Proteins - metabolism; Neuroblastoma - pathology; Neurology; Oncogene Proteins - antagonists & inhibitors; Oncogene Proteins - genetics; Oncogene Proteins - metabolism; paraquat; Paraquat - pharmacology; Parkinson disease; Parkinson's disease; Protein Deglycase DJ-1; RNA, Small Interfering - metabolism; RNA, Small Interfering - pharmacology; Transfection; Tumors of the nervous system. Phacomatoses; Vacuoles - drug effects; Vacuoles - pathology
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1111/j.1471-4159.2009.06020.x

The role of autophagy as a survival strategy of cells constitutes an emerging topic in the study of the pathogenesis of several diseases with autophagic changes being described in a number of age-related neurodegenerative disorders, including Parkinson's disease (PD). Although the etiology of PD is still unknown, both environmental (for example, paraquat exposure) and genetic factors have been investigated as putative causes of the disease. In the latter case, mutations or changes in the protein DJ-1 have been reported to be associated with autosomal recessive, early-onset parkinsonism. In this paper we established a model system to study the involvement of the DJ-1 protein in paraquat-induced autophagy. When human neuroblastoma SH-SY5Y cells were transfected with DJ-1-specific small interfering RNAs and exposed to paraquat, we observed (i) sensitization additive with paraquat-induced apoptotic cell death, (ii) inhibition of the cytoplasmic accumulation of autophagic vacuoles as well as the recruitment of LC3 fusion protein to the vacuoles, (iii) exacerbation of apoptotic cell death in the presence of the autophagy inhibitor 3-methyladenine, and (iv) an increase in mammalian target of rapamycin phosphorylation. Taken together, these findings suggest an active role for DJ-1 in the autophagic response produced by paraquat, providing evidence for the role of PD-related proteins in the autophagic degradation pathway, a factor that should be considered in the design of potential therapies for the treatment of the disease.