X-linked Inhibitor of Apoptosis-associated Factor 1 Regulates TNF Receptor 1 Complex Stability
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X-linked inhibitor of apoptosis (XIAP)-associated factor 1 (XAF1) is a cytokine-regulated, tumor necrosis factor (TNF) receptor-associated factor (TRAF) domain-containing protein that has a poorly defined cellular function. Here, we show that ectopically expressed XAF1 inhibits TNF-ɑ-induced NF-κB activation, whereas shRNA silencing of endogenous XAF1 augments it. Our data suggest that XAF1 may inhibit TNF-ɑ-induced NF-κB activation by disrupting the assembly of the TRADD/TRAF2/RIP1 complex (complex I) downstream of TNF receptor activation. XAF1 interacts with TRAF2 and inhibits TRAF2-dependent NF-κB activation, in part, by blocking TRAF2 polyubiquitination. Our findings also indicate that although XAF1 does not directly inhibit RIP1-dependent NF-κB activation, it binds RIP1 and disrupts RIP1/TRADD association. Our data suggest that XAF1 acts as a feedback regulator of the TNF receptor signaling pathway to suppress NF-κB activation.
Shahbaz S, Jovel J, Elahi S Clin Transl Immunology. 2021; 10(5):e1289.
PMID: 34094548 PMC: 8155695. DOI: 10.1002/cti2.1289.
Gao X, Liu Y, Zou S, Liu P, Zhao J, Yang C J Med Virol. 2021; 93(9):5544-5554.
PMID: 34009691 PMC: 8242610. DOI: 10.1002/jmv.27093.