ZUP1 is a key component of the MAVS complex and acts as a protector of host against viral invasion

Abstract Zinc finger‐containing ubiquitin peptidase 1 (ZUP1) is a protein characterized by four N‐terminal zinc finger domains and a C‐terminal deubiquitinase (DUB) domain. While it is associated with the DNA damage response, the role of ZUP1 in innate immunity remains unclear. Here, we identify ZUP1 as a crucial component of the mitochondrial antiviral signaling (MAVS) complex, essential for host antiviral defense. We show that viral infection significantly upregulates ZUP1 expression, and mice lacking ZUP1 exhibit impaired type I interferon (IFN) production and increased susceptibility to viral infection, as evidenced by higher mortality rates. This underscores the protective role of ZUP1 in host immunity. Mechanistically, ZUP1 binds to MAVS through its C‐terminal domain independently of DUB activity. Instead, ZUP1 utilizes its zinc finger domains, particularly the third zinc finger, to directly bind viral RNA. This interaction enhances the association of ZUP1 with MAVS and promotes its aggregation on mitochondria during viral infection. ZUP1 also interacts with TBK1 and NEMO within the MAVS complex, facilitating IRF3 activation and type I IFN production. These findings establish ZUP1 as a zinc finger‐containing regulator that amplifies MAVS‐dependent antiviral immunity, linking viral RNA recognition to downstream signaling and highlighting potential targets for therapeutic intervention against viral infections.