title: Macroautophagy-generated increase of lysosomal amyloid β-protein mediates oxidant-induced apoptosis of cultured neuroblastoma cells.
abstract: Increasing evidence suggests the toxicity of intracellular amyloid β-protein (Aβ) to neurons, as well as the involvement of oxidative stress in Alzheimer disease (AD). Here we show that normobaric hyperoxia (exposure of cells to 40% oxygen for five days), and consequent activation of macroautophagy and accumulation of Aβ within lysosomes, induced apoptosis in differentiated SH-SY5Y neuroblastoma cells. Cells under hyperoxia showed: (1) increased numbers of autophagic vacuoles that contained amyloid precursor protein (APP) as well as Aβ monomers and oligomers, (2) increased reactive oxygen species production, and (3) enhanced apoptosis. Oxidant-induced apoptosis positively correlated with cellular Aβ production, being the highest in cells that were stably transfected with APP Swedish KM670/671NL double mutation. Inhibition of γ-secretase, prior and/or in parallel to hyperoxia, suggested that the increase of lysosomal Aβ resulted mainly from its autophagic uptake, but also from APP processing within autophagic vacuoles. The oxidative stress-mediated effects were prevented by macroautophagy inhibition using 3-methyladenine or ATG5 downregulation. Our results suggest that upregulation of macroautophagy and resulting lysosomal Aβ accumulation are essential for oxidant-induced apoptosis in cultured neuroblastoma cells and provide additional support for the interactive role of oxidative stress and the lysosomal system in AD-related neurodegeneration.
authors: Division of Geriatric Medicine, Department of Clinical and Experimental Medicine, IKE, Faculty of Health Sciences, Linköping University, Linköping, Sweden. lin.zheng@liu.se
authors: Lin
authors: L
authors: Zheng
authors: Alexei
authors: A
authors: Terman
authors: Martin
authors: M
authors: Hallbeck
authors: Nodi
authors: N
authors: Dehvari
authors: Richard F
authors: RF
authors: Cowburn
authors: Eirikur
authors: E
authors: Benedikz
authors: Katarina
authors: K
authors: Kågedal
authors: Angel
authors: A
authors: Cedazo-Minguez
authors: Jan
authors: J
authors: Marcusson
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D053829:Amyloid Precursor Protein Secretases / Q000037:antagonists & inhibitors / Q000378:metabolism; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D017209:Apoptosis / Q000187:drug effects*; D001343:Autophagy / Q000187:drug effects*; D000071187:Autophagy-Related Protein 5; D002454:Cell Differentiation / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D002470:Cell Survival / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects; D006801:Humans; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D052119:Lysosomal-Associated Membrane Protein 2; D051907:Lysosomal Membrane Proteins / Q000378:metabolism; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D050505:Mutant Proteins / Q000378:metabolism; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology*; D016877:Oxidants / Q000494:pharmacology*; D010100:Oxygen / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D014162:Transfection; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014617:Vacuoles / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure
chemical_list: C502778:ATG5 protein, human; D016229:Amyloid beta-Peptides; D000071187:Autophagy-Related Protein 5; C497811:LAMP2 protein, human; D052119:Lysosomal-Associated Membrane Protein 2; D051907:Lysosomal Membrane Proteins; D008869:Microtubule-Associated Proteins; D050505:Mutant Proteins; D016877:Oxidants; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; C025946:3-methyladenine; D014212:Tretinoin; D053829:Amyloid Precursor Protein Secretases; D000225:Adenine; D010100:Oxygen