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Abstract: The RIG‐I‐like receptors (RLRs) are critical for protection against RNA virus infection, and their activities must be stringently controlled to maintain immune homeostasis. Here, we report that leucine‐rich repeat containing protein 25 (LRRC25) is a key negative regulator of RLR‐mediated type I interferon (IFN) signaling. Upon RNA virus infection, LRRC25 specifically binds to ISG15‐associated RIG‐I to promote interaction between RIG‐I and the autophagic cargo receptor p62 and to mediate RIG‐I degradation via selective autophagy. Depletion of either LRRC25 or ISG15 abrogates RIG‐I‐p62 interaction as well as the autophagic degradation of RIG‐I. Collectively, our findings identify a previously unrecognized role of LRRC25 in type I IFN signaling activation by which LRRC25 acts as a secondary receptor to assist RIG‐I delivery to autophagosomes for degradation in a p62‐dependent manner. [ABSTRACT FROM AUTHOR]

Autophagy, mediated by a number of autophagy-related ( ATG) proteins, plays an important role in the bulk degradation of cellular constituents. Beclin-1 (also known as Atg6 in yeast) is a core protein essential for autophagic initiation and other biological processes. The activity of Beclin-1 is tightly regulated by multiple post-translational modifications, including ubiquitination, yet the molecular mechanism underpinning its reversible deubiquitination remains poorly defined. Here, we identified ubiquitin-specific protease 19 ( USP19) as a positive regulator of autophagy, but a negative regulator of type I interferon ( IFN) signaling. USP19 stabilizes Beclin-1 by removing the K11-linked ubiquitin chains of Beclin-1 at lysine 437. Moreover, we found that USP19 negatively regulates type I IFN signaling pathway, by blocking RIG-I- MAVS interaction in a Beclin-1-dependent manner. Depletion of either USP19 or Beclin-1 inhibits autophagic flux and promotes type I IFN signaling as well as cellular antiviral immunity. Our findings reveal novel dual functions of the USP19-Beclin-1 axis by balancing autophagy and the production of type I IFNs. [ABSTRACT FROM AUTHOR]