title: The relationship between Cd-induced autophagy and lysosomal activation in WRL-68 cells.
abstract: This study shows that Cd induces autophagy in the human's embryonic normal liver cell line (WRL-68). The expression of LC3B-II and the mature cathepsin L were analyzed by Western blotting. The autophagosomes and lysosomes were directly visualized by electron microscopy and confocal microscopy analysis in Cd-exposed WRL-68 cells. In this study, we first found that autophagy induced the activation of lysosomal function in WRL-68 cells. The lysosomal activation was markedly decreased when the cells were co-treated with 3-MA (an inhibitor of autophagy). Secondly, we provided the evidence that the activation of lysosomal function depended on autophagosome-lysosome fusion. The colocalization of lysosome-associated membrane protein-2 (LAMP2) and GFP-LC3 was significantly reduced, when they were treated with thapsigargin (an inhibitor of autophagosome-lysosome fusion). We demonstrated that deletion or blockage of the autophagosome-lysosome fusion process effectively diminished lysosomal activation, which suggests that lysosomal activation occurring in the course of autophagy is dependent on autophagosome-lysosome fusion. Thirdly, we provided evidence that the activation of lysosomal function was associated with lysosomal acid. We investigated the relationship between autophagosome-lysosome fusion and pH in acidic compartments by visualizing fusion process in WRL-68 cells. This suggests that increasing pH in acidic compartments in WRL-68 cells inhibits the autophagosome-lysosome fusion. Finally, we found that the activation of lysosomal function was associated with Ca(2+) stores and the intracellular Ca(2+) channels or pumps were possibly pH-dependent.
authors: Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, Jiangsu, People's Republic of China.
authors: Su-Fang
authors: SF
authors: Meng
authors: Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, Jiangsu, People's Republic of China.
authors: Wei-Ping
authors: WP
authors: Mao
authors: Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, Jiangsu, People's Republic of China.
authors: Fang
authors: F
authors: Wang
authors: Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, Jiangsu, People's Republic of China.
authors: Xiao-Qian
authors: XQ
authors: Liu
authors: Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, Jiangsu, People's Republic of China.
authors: Luan-Luan
authors: LL
authors: Shao
mesh_terms: D001343:Autophagy / Q000187:drug effects*; D002104:Cadmium / Q000633:toxicity*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D002460:Cell Line; D022781:Hepatocytes / Q000187:drug effects*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D052119:Lysosomal-Associated Membrane Protein 2 / Q000235:genetics / Q000378:metabolism; D008247:Lysosomes / Q000187:drug effects*; D050576:Membrane Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D015220:Calcium Channels; C497811:LAMP2 protein, human; D052119:Lysosomal-Associated Membrane Protein 2; D050576:Membrane Fusion Proteins; D002104:Cadmium
keywords: autophagosome-lysosome fusion; autophagy; calcium; lysosomal acid; lysosomal activation