OTUB1 Is a Key Regulator of RIG-I-Dependent Immune Signaling and Is Targeted for Proteasomal Degradation by Influenza A NS1

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Jahan, Akhee Sabiha | Biquand, Elise | Muñoz-Moreno, Raquel | Le Quang, Agathe | Mok, Chris Ka-Pun | Wong, Ho Him | Teo, Qi Wen | Valkenburg, Sophie, A | Chin, Alex W.H. | Man Poon, Leo Lit | Te Velthuis, Artejan | García-Sastre, Adolfo | Demeret, Caroline | Sanyal, Sumana

Edité par CCSD ; Elsevier Inc -

International audience. Deubiquitylases (DUBs) regulate critical signaling pathways at the intersection of host immunity and viral pathogenesis. Although RIG-I activation is heavily dependent on ubiquitylation, systematic analyses of DUBs that regulate this pathway have not been performed. Using a ubiquitin C-terminal electrophile, we profile DUBs that function during influenza A virus (IAV) infection and isolate OTUB1 as a key regulator of RIG-I-dependent antiviral responses. Upon infection, OTUB1 relocalizes from the nucleus to mitochondrial membranes together with RIG-I, viral PB2, and NS1. Its expression depends on competing effects of interferon stimulation and IAV-triggered degradation. OTUB1 activates RIG-I via a dual mechanism of K48 polyubiquitin hydrolysis and formation of an E2-repressive complex with UBCH5c. We reconstitute this mechanism in a cell-free system comprising [35S]IRF3, purified RIG-I, mitochondrial membranes, and cytosol expressing OTUB1 variants. A range of IAV NS1 proteins trigger proteasomal degradation of OTUB1, antagonizing the RIG-I signaling cascade and antiviral responses.

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