title: Glycogen Synthase Kinase-3β and Caspase-2 Mediate Ceramide- and Etoposide-Induced Apoptosis by Regulating the Lysosomal-Mitochondrial Axis.
abstract: Glycogen synthase kinase-3β (GSK-3β) regulates the sequential activation of caspase-2 and caspase-8 before mitochondrial apoptosis. Here, we report the regulation of Mcl-1 destabilization and cathepsin D-regulated caspase-8 activation by GSK-3β and caspase-2. Treatment with either the ceramide analogue C2-ceramide or the topoisomerase II inhibitor etoposide sequentially induced lysosomal membrane permeabilization (LMP), the reduction of mitochondrial transmembrane potential, and apoptosis. Following LMP, cathepsin D translocated from lysosomes to the cytoplasm, whereas inhibiting cathepsin D blocked mitochondrial apoptosis. Furthermore, cathepsin D caused the activation of caspase-8 but not caspase-2. Inhibiting GSK-3β and caspase-2 blocked Mcl-1 destabilization, LMP, cathepsin D re-localization, caspase-8 activation, and mitochondrial apoptosis. Expression of Mcl-1 was localized to the lysosomes, and forced expression of Mcl-1 prevented apoptotic signaling via the lysosomal-mitochondrial pathway. These results demonstrate the importance of GSK-3β and caspase-2 in ceramide- and etoposide-induced apoptosis through mechanisms involving Mcl-1 destabilization and the lysosomal-mitochondrial axis.
authors.affiliation: Department of Microbiology and Immunology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, 110, Taiwan.|Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, 110, Taiwan.
authors.forename: Chiou-Feng
authors.initials: CF
authors.lastname: Lin
authors.affiliation: Department of Nursing, Chung Hwa University of Medical Technology, Tainan, 717, Taiwan.
authors.forename: Cheng-Chieh
authors.initials: CC
authors.lastname: Tsai
authors.affiliation: Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, 701, Taiwan.
authors.forename: Wei-Ching
authors.initials: WC
authors.lastname: Huang
authors.affiliation: Department of Microbiology and Immunology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, 110, Taiwan.
authors.forename: Yu-Chih
authors.initials: YC
authors.lastname: Wang
authors.affiliation: Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, 701, Taiwan.
authors.forename: Po-Chun
authors.initials: PC
authors.lastname: Tseng
authors.affiliation: Department of Microbiology and Immunology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, 110, Taiwan.
authors.forename: Tsung-Ting
authors.initials: TT
authors.lastname: Tsai
authors.affiliation: Translational Research Center, Taipei Medical University, Taipei, 110, Taiwan.
authors.forename: Chia-Ling
authors.initials: CL
authors.lastname: Chen
mesh_terms: D000818:Animals; D053143:Caspase 2 / Q000378:metabolism*; D002460:Cell Line; D002518:Ceramides / Q000494:pharmacology*; D005047:Etoposide / Q000494:pharmacology*; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D008247:Lysosomes / Q000187:drug effects / Q000201:enzymology*; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology*
chemical_list: D002518:Ceramides; D005047:Etoposide; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D038362:Glycogen Synthase Kinase 3; D053143:Caspase 2