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TIR ‐domain‐containing adapter‐inducing interferon‐β ( TRIF ) forms filamentous structures, whose pro‐apoptotic signalling is terminated by autophagy
Author(s) -
Gentle Ian E.,
McHenry Kevin T.,
Weber Arnim,
Metz Arlena,
Kretz Oliver,
Porter Dale,
Häcker Georg
Publication year - 2017
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.14091
Subject(s) - trif , signal transducing adaptor protein , microbiology and biotechnology , autophagy , innate immune system , signal transduction , tlr3 , tlr2 , biology , death domain , autophagosome , toll like receptor , chemistry , apoptosis , receptor , programmed cell death , tlr4 , biochemistry
The formation of amyloid‐like protein structures has recently emerged as a feature in signal transduction, particularly in innate immunity. These structures appear to depend on defined domains for their formation but likely also require dedicated ways to terminate signalling. We, here, define the innate immunity protein/Toll‐like receptor adaptor TIR‐domain‐containing adapter‐inducing interferon‐β ( TRIF ) as a novel platform of fibril formation and probe signal initiation through TRIF as well as its termination in Toll‐like receptor 3 ( TLR 3)‐stimulated melanoma cells. A main signalling pathway triggered by TLR 3 caused apoptosis, which was controlled by inhibitor of apoptosis proteins and was dependent on RIPK 1 and independent of TNF . Using correlative electron/fluorescence microscopy, we visualised fibrillar structures formed through both Toll/interleukin‐1 receptor and RIP homotypic interacting motif regions of TRIF . We provide evidence that these fibrillary structures are active signalling platforms whose activity is terminated by autophagy. TRIF ‐signalling enhanced autophagy, and fibrillary structures were partly contained within autophagosomes. Inhibition of autophagy increased levels of pro‐apoptotic TRIF complexes, leading to the accumulation of active caspase‐8 and enhanced apoptosis while stimulation of autophagy reduced TRIF ‐dependent death. We conclude that pro‐death signals through TRIF are regulated by autophagy and propose that pro‐apoptotic signalling through TRIF / RIPK 1/caspase‐8 occurs in fibrillary platforms.