RBM10 suppresses porcine epidemic diarrhea virus replication by degrading nonstructural protein 3 through selective autophagy.

Porcine Epidemic Diarrhea Virus (PEDV) causes highly contagious intestinal disease in swine and results in severe economic losses worldwide. PEDV Nsp3, a nonstructural protein produced in the early stage of viral replication, is responsible for cleaving polyproteins to generate nonstructural proteins and the replication-transcription complex, as well as inducing the formation of coronavirus replication organelles known as double-membrane vesicles (DMVs). Nsp3 is a key protein for viral replication; however, its specific mechanism of action remains unclear. To investigate the role of Nsp3 during viral infection, we performed LC-MS/MS analysis and identified 29 host proteins that potentially interact with Nsp3, among which RBM10 was selected for further study. This study confirms that RBM10 is a host factor that restricts PEDV replication, as validated by functional assays: RBM10 inhibits PEDV replication, while knockdown of RBM10 abolishes this inhibitory effect. This study proposes for the first time an RBM10-MARCHF9-Nsp3-p62 axis, which mediates the selective autophagic degradation of PEDV Nsp3. Mechanistically, RBM10 recruits the E3 ligase MARCHF9 to catalyze K33-linked ubiquitination of Nsp3. Subsequently, the ubiquitinated cargo is recognized by the selective autophagy receptor p62 and delivered to autophagosomes for degradation. Blocking autophagic flux, knocking down p62, or silencing key autophagy-related proteins restores Nsp3 protein levels. In summary, this study confirms RBM10 as a novel anti-PEDV host factor, providing new theoretical insights into host-directed regulatory mechanisms of PEDV replication and suggesting that RBM10 may serve as a potential target for the development of novel anti-PEDV strategies.