title: Necrosis-like death can engage multiple pro-apoptotic Bcl-2 protein family members.
abstract: Necroptosis is a physiologically relevant mode of cell death with some well-described initiating events, but largely unknown executioners. Here we investigated necrostatin-1 (Nec-1) sensitive death elicited by different necroptosis stimuli in L929 mouse fibrosarcoma cells, mouse embryonic fibroblasts (MEF) and bone marrow-derived macrophages. We found that TNFα- or zVAD-induced necroptosis occurs independently of the recently implicated executioners Bmf or PARP-2, but can involve the Bcl-2 family proteins Bid and Bak. Furthermore, this type of necroptosis is associated with mitochondrial cytochrome c release and partly sensitive to cyclosporine A inhibition, suggesting a cross talk with the mitochondrial permeability transition pore. Necroptosis triggered by cadmium (Cd) exposure caused fully Nec-1-sensitive and caspase-independent death in L929 cells that was associated with autocrine TNFα-mediated feed-forward signalling. In MEF Cd-exposure elicited a mixed mode of cell death that was to some extent Nec-1-sensitive but also displayed features of apoptosis. It was partly dependent on Bmf and Bax/Bak, proteins typically considered to act pro-apoptotic, but ultimately insensitive to caspase inhibition. Overall, our study indicates that inducers of "extrinsic" and "intrinsic" necroptosis can both trigger TNF-receptor signalling. Further, necroptosis may depend on mitochondrial changes engaging proteins considered critical for MOMP during apoptosis that ultimately contribute to caspase-independent necrotic cell death.
authors.affiliation: Division of Developmental Immunology, Biocenter, Medical University Innsbruck, 6020 Innsbruck, Austria.
authors.forename: Denise
authors.initials: D
authors.lastname: Tischner
authors.affiliation: Division of Developmental Immunology, Biocenter, Medical University Innsbruck, 6020 Innsbruck, Austria.
authors.forename: Claudia
authors.initials: C
authors.lastname: Manzl
authors.affiliation: Division of Developmental Immunology, Biocenter, Medical University Innsbruck, 6020 Innsbruck, Austria.
authors.forename: Claudia
authors.initials: C
authors.lastname: Soratroi
authors.affiliation: Division of Developmental Immunology, Biocenter, Medical University Innsbruck, 6020 Innsbruck, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Villunger
authors.affiliation: Division of Developmental Immunology, Biocenter, Medical University Innsbruck, 6020 Innsbruck, Austria.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Krumschnabel
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D019898:Autocrine Communication / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects; D051023:BH3 Interacting Domain Death Agonist Protein / Q000378:metabolism; D002104:Cadmium / Q000633:toxicity; D002460:Cell Line; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D007093:Imidazoles / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D009336:Necrosis / Q000378:metabolism* / Q000473:pathology*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D053422:Receptor-Interacting Protein Serine-Threonine Kinases / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000590:Amino Acid Chloromethyl Ketones; D051023:BH3 Interacting Domain Death Agonist Protein; C435486:Bmf protein, mouse; D007093:Imidazoles; D007211:Indoles; D019253:Proto-Oncogene Proteins c-bcl-2; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D050998:bcl-2 Homologous Antagonist-Killer Protein; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C507699:necrostatin-1; D002104:Cadmium; D011065:Poly(ADP-ribose) Polymerases; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; C506251:Ripk1 protein, mouse; C485615:Ripk3 protein, mouse