title: TRAIL activates acid sphingomyelinase via a redox mechanism and releases ceramide to trigger apoptosis.
abstract: We have previously shown that activation of the acid sphingomyelinase (ASM), the release of ceramide and the formation of ceramide-enriched membrane domains are central for the induction of apoptosis by CD95. Here, we demonstrate that tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and CD95 activate the ASM via a redox mechanism resulting in release of ceramide and formation of ceramide-enriched membrane platforms. Ceramide-enriched membrane platforms serve to cluster DR5 upon stimulation. Antioxidants prevent TRAIL-mediated stimulation of ASM, the release of ceramide, the formation of ceramide-enriched membrane platforms and the induction of apoptosis by TRAIL. Further, ASM-deficient splenocytes fail to cluster DR5 in ceramide-enriched membrane domains upon TRAIL stimulation and resist TRAIL-induced apoptosis, events that were restored by addition of natural C(16)-ceramide. A dose-response analysis indicates that ceramide-enriched membrane platforms greatly sensitized tumor cells to TRAIL-induced apoptosis. Our data indicate that ceramide-enriched membrane platforms are required for the signaling of TRAIL-DR5 complexes under physiological conditions.
authors.affiliation: Department of Molecular Biology, University of Duisburg-Essen, Hufelandstrasse 55, 45122 Essen, Germany.
authors.forename: C A
authors.initials: CA
authors.lastname: Dumitru
authors.forename: E
authors.initials: E
authors.lastname: Gulbins
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000502:physiology*; D002460:Cell Line; D002518:Ceramides / Q000378:metabolism*; D004789:Enzyme Activation; D006801:Humans; D007150:Immunohistochemistry; D008562:Membrane Glycoproteins / Q000502:physiology*; D051379:Mice; D010084:Oxidation-Reduction; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism*; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*
chemical_list: D051017:Apoptosis Regulatory Proteins; D002518:Ceramides; D008562:Membrane Glycoproteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; C505654:Tnfsf10 protein, mouse; D014409:Tumor Necrosis Factor-alpha; D013108:Sphingomyelin Phosphodiesterase