Selective autophagy controls the stability of TBK1 via NEDD4 to balance host defense.

Abstract

As a core kinase of antiviral immunity, the activity and stability of TANK-binding kinase 1 (TBK1) is tightly controlled by multiple post-translational modifications. Although it has been demonstrated that TBK1 stability can be regulated by ubiquitin-dependent proteasome pathway, it is unclear whether another important protein degradation pathway, autophagosome pathway, can specifically affect TBK1 degradation by cargo receptors. Here we report that E3 ubiquitin ligase NEDD4 functions as a negative regulator of type I interferon (IFN) signaling by targeting TBK1 for degradation at the late stage of viral infection, to prevent the host from excessive immune response. Mechanically NEDD4 catalyzes the K27-linked poly-ubiquitination of TBK1 at K344, which serves as a recognition signal for cargo receptor NDP52-mediated selective autophagic degradation. Taken together, our study reveals the regulatory role of NEDD4 in balancing TBK1-centered type I IFN activation and provides insights into the crosstalk between selective autophagy and antiviral signaling.