Abstract
Autophagic cargoes ensure selective autophagy for the recognition and removal of various cytosolic aggregated proteins, damaged organelles, or pathogens. Stress granules (SGs), as antiviral immune complexes, serve a positive role in the type I interferon (IFN) response and can be targeted by autophagy (termed granulophagy). However, the cargo of granulophagy remains elusive, and it is still unknown whether granulophagy plays a role in viral infection. Here, we found that histone deacetylase 6 (HDAC6), a component of viral RNA-induced SGs, is a novel granulophagic cargo that is recognized by p62/Sequestosome 1 (SQSTM1) and mediates the degradation of SGs in coxsackievirus A16 (CA16)-infected cells. CA16 viral RNA activated the protein kinase RNA-activated (PKR)/eukaryotic translation initiation factor 2-alpha (eIF2α) pathway to promote SG assembly. The SGs were degraded by CA16-triggered autophagy via the interaction between the ubiquitin-associated (UBA) domain of p62 and the ubiquitin-binding domain (UBD) of HDAC6, which was bridged by a poly-ubiquitin chain. We also found that granulophagy repressed the type I interferon response and facilitated viral replication. These results suggest that HDAC6 might be the first identified granulophagic cargo and granulophagy could be a strategy that viruses apply to repress the antiviral immune response.