RIPK1 counteracts ZBP1-mediated necroptosis to inhibit inflammation.
Receptor-interacting protein kinase 1 (RIPK1) regulates cell death and inflammation through kinase-dependent and -independent functions. RIPK1 kinase activity induces caspase-8-dependent apoptosis and RIPK3 and mixed lineage kinase like (MLKL)-dependent necroptosis. In addition, RIPK1 inhibits apoptosis and necroptosis through kinase-independent functions, which are important for late embryonic development and the prevention of inflammation in epithelial barriers. The mechanism by which RIPK1 counteracts RIPK3-MLKL-mediated necroptosis has remained unknown. Here we show that RIPK1 prevents skin inflammation by inhibiting activation of RIPK3-MLKL-dependent necroptosis mediated by Z-DNA binding protein 1 (ZBP1, also known as DAI or DLM1). ZBP1 deficiency inhibited keratinocyte necroptosis and skin inflammation in mice with epidermis-specific RIPK1 knockout. Moreover, mutation of the conserved RIP homotypic interaction motif (RHIM) of endogenous mouse RIPK1 (RIPK1mRHIM) caused perinatal lethality that was prevented by RIPK3, MLKL or ZBP1 deficiency. Furthermore, mice expressing only RIPK1mRHIMin keratinocytes developed skin inflammation that was abrogated by MLKL or ZBP1 deficiency. Mechanistically, ZBP1 interacted strongly with phosphorylated RIPK3 in cells expressing RIPK1mRHIM, suggesting that the RIPK1 RHIM prevents ZBP1 from binding and activating RIPK3. Collectively, these results show that RIPK1 prevents perinatal death as well as skin inflammation in adult mice by inhibiting ZBP1-induced necroptosis. Furthermore, these findings identify ZBP1 as a critical mediator of inflammation beyond its previously known role in antiviral defence and suggest that ZBP1 might be implicated in the pathogenesis of necroptosis-associated inflammatory diseases.
Institute for Genetics, Centre for Molecular Medicine (CMMC), and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany.
Juan
J
Lin
Institute for Genetics, Centre for Molecular Medicine (CMMC), and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany.
Snehlata
S
Kumari
Institute for Genetics, Centre for Molecular Medicine (CMMC), and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany.
Chun
C
Kim
Institute for Genetics, Centre for Molecular Medicine (CMMC), and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany.
Trieu-My
TM
Van
Institute for Genetics, Centre for Molecular Medicine (CMMC), and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany.
Laurens
L
Wachsmuth
Institute for Genetics, Centre for Molecular Medicine (CMMC), and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany.
Apostolos
A
Polykratis
Institute for Genetics, Centre for Molecular Medicine (CMMC), and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany.
Manolis
M
Pasparakis
D000818:Animals; D017209:Apoptosis; D006023:Glycoproteins / Q000037:antagonists & inhibitors* / Q000172:deficiency / Q000378:metabolism*; D007249:Inflammation / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D015603:Keratinocytes / Q000378:metabolism / Q000473:pathology; D051379:Mice; D009154:Mutation; D009336:Necrosis; D010766:Phosphorylation; D000072417:Protein Domains / Q000235:genetics; D011494:Protein Kinases / Q000172:deficiency / Q000378:metabolism; D016601:RNA-Binding Proteins; D053422:Receptor-Interacting Protein Serine-Threonine Kinases / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D012867:Skin / Q000378:metabolism / Q000473:pathology
D006023:Glycoproteins; D016601:RNA-Binding Proteins; C402632:Zbp1 protein, mouse; C570694:MLKL protein, mouse; D011494:Protein Kinases; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; C506251:Ripk1 protein, mouse; C485615:Ripk3 protein, mouse