BACKGROUND: Activation of Fas (CD95) by its ligand (FasL) rapidly induces cell death through recruitment and activation of caspase-8 via the adaptor protein Fas-associated death domain protein (FADD). However, Fas signals do not always result in apoptosis but can also trigger a pathway that leads to proliferation. We investigated the level at which the two conflicting Fas signals diverge and the protein(s) that are implicated in switching the response. RESULTS: Under conditions in which proliferation of CD3-activated human T lymphocytes is increased by recombinant FasL, there was activation of the transcription factors NF-kappaB and AP-1 and recruitment of the caspase-8 inhibitor and FADD-interacting protein FLIP (FLICE-like inhibitory protein). Fas-recruited FLIP interacts with TNF-receptor associated factors 1 and 2, as well as with the kinases RIP and Raf-1, resulting in the activation of the NF-kappaB and extracellular signal regulated kinase (Erk) signaling pathways. In T cells these two signal pathways are critical for interleukin-2 production. Increased expression of FLIP in T cells resulted in increased production of interleukin-2. CONCLUSIONS: We provide evidence that FLIP is not simply an inhibitor of death-receptor-induced apoptosis but that it also mediates the activation of NF-kappaB and Erk by virtue of its capacity to recruit adaptor proteins involved in these signaling pathways.
BACKGROUND: Activation of Fas (CD95) by its ligand (FasL) rapidly induces cell death through recruitment and activation of caspase-8 via the adaptor protein Fas-associated death domain protein (FADD). However, Fas signals do not always result in apoptosis but can also trigger a pathway that leads to proliferation. We investigated the level at which the two conflicting Fas signals diverge and the protein(s) that are implicated in switching the response. RESULTS: Under conditions in which proliferation of CD3-activated human T lymphocytes is increased by recombinant FasL, there was activation of the transcription factors NF-kappaB and AP-1 and recruitment of the caspase-8 inhibitor and FADD-interacting protein FLIP (FLICE-like inhibitory protein). Fas-recruited FLIP interacts with TNF-receptor associated factors 1 and 2, as well as with the kinases RIP and Raf-1, resulting in the activation of the NF-kappaB and extracellular signal regulated kinase (Erk) signaling pathways. In T cells these two signal pathways are critical for interleukin-2 production. Increased expression of FLIP in T cells resulted in increased production of interleukin-2. CONCLUSIONS: We provide evidence that FLIP is not simply an inhibitor of death-receptor-induced apoptosis but that it also mediates the activation of NF-kappaB and Erk by virtue of its capacity to recruit adaptor proteins involved in these signaling pathways.
Authors: T H Holmström; I Schmitz; T S Söderström; M Poukkula; V L Johnson; S C Chow; P H Krammer; J E Eriksson Journal: EMBO J Date: 2000-10-16 Impact factor: 11.598
Authors: Qi-Quan Huang; Robert Birkett; Renee E Doyle; G Kenneth Haines; Harris Perlman; Bo Shi; Philip Homan; Lianping Xing; Richard M Pope Journal: Arthritis Rheumatol Date: 2017-08-01 Impact factor: 10.995