E3 ligase SYVN1-mediated polyubiquitination of CPSF6 promotes alternative polyadenylation and antivirus effects of macrophages.

Transcriptome-wide alternative polyadenylation (APA) is involved in both innate and adaptive immune responses of immune cells. Downregulation of the CPSF6 protein, one of the 3' end-processing factors, mediates APA in macrophages with responses to virus infection and plays an important role in its anti-virus effect. However, the signaling pathway and molecular mechanism underlying the downregulation of the CPSF6 protein remain elusive. Here, we found that MAVS triggers the nuclear import of the E3 ligase SYVN1 mediated by NUP153 in response to vesicular stomatitis virus infection. Then, SYVN1 catalyzes K48-linked polyubiquitination of CPSF6, resulting in degradation of CPSF6 via the proteasome and then transcriptome-wide APA and anti-virus effects. Our results identify an antiviral mechanism via APA regulation based on ubiquitination modification of the CPSF6 protein, which may serve as a target for developing immune interventions.