title: RIPK1- and RIPK3-induced cell death mode is determined by target availability.
abstract: Both receptor-interacting protein kinase 1 (RIPK1) and RIPK3 can signal cell death following death receptor ligation. To study the requirements for RIPK-triggered cell death in the absence of death receptor signaling, we engineered inducible versions of RIPK1 and RIPK3 that can be activated by dimerization with the antibiotic coumermycin. In the absence of TNF or other death ligands, expression and dimerization of RIPK1 was sufficient to cause cell death by caspase- or RIPK3-dependent mechanisms. Dimerized RIPK3 induced cell death by an MLKL-dependent mechanism but, surprisingly, also induced death mediated by FADD, caspase 8 and RIPK1. Catalytically active RIPK3 kinase domains were essential for MLKL-dependent but not for caspase 8-dependent death. When RIPK1 or RIPK3 proteins were dimerized, the mode of cell death was determined by the availability of downstream molecules such as FADD, caspase 8 and MLKL. These observations imply that rather than a 'switch' operating between the two modes of cell death, the final mechanism depends on levels of the respective signaling and effector proteins.
authors.affiliation: La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Bundoora, Victoria 3086, Australia.
authors.forename: W D
authors.initials: WD
authors.lastname: Cook
authors.affiliation: 1] The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Melbourne, Victoria 3052, Australia [2] Department of Medical Biology, University of Melbourne, Parkville, Victoria 3050, Australia.
authors.forename: D M
authors.initials: DM
authors.lastname: Moujalled
authors.affiliation: La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Bundoora, Victoria 3086, Australia.
authors.forename: T J
authors.initials: TJ
authors.lastname: Ralph
authors.affiliation: La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Bundoora, Victoria 3086, Australia.
authors.forename: P
authors.initials: P
authors.lastname: Lock
authors.affiliation: 1] The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Melbourne, Victoria 3052, Australia [2] Department of Medical Biology, University of Melbourne, Parkville, Victoria 3050, Australia.
authors.forename: S N
authors.initials: SN
authors.lastname: Young
authors.affiliation: 1] The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Melbourne, Victoria 3052, Australia [2] Department of Medical Biology, University of Melbourne, Parkville, Victoria 3050, Australia.
authors.forename: J M
authors.initials: JM
authors.lastname: Murphy
authors.affiliation: 1] The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Melbourne, Victoria 3052, Australia [2] Department of Medical Biology, University of Melbourne, Parkville, Victoria 3050, Australia.
authors.forename: D L
authors.initials: DL
authors.lastname: Vaux
mesh_terms: D049933:Aminocoumarins / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D002460:Cell Line; D053200:Fas-Associated Death Domain Protein / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D011494:Protein Kinases / Q000378:metabolism; D055503:Protein Multimerization / Q000235:genetics*; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D053422:Receptor-Interacting Protein Serine-Threonine Kinases / Q000235:genetics*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D049933:Aminocoumarins; C505534:Fadd protein, mouse; D053200:Fas-Associated Death Domain Protein; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; C570694:MLKL protein, mouse; D011494:Protein Kinases; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; C506251:Ripk1 protein, mouse; C485615:Ripk3 protein, mouse; D053148:Caspase 3; D053181:Caspase 8; C004628:coumermycin