Interaction between PHB2 and Enterovirus A71 VP1 Induces Autophagy and Affects EV-A71 Infection

Abstract

Enterovirus A71 (EV-A71) is a major pathogen that causes severe and fatal cases of hand-foot-and-mouth disease (HFMD). HFMD caused by EV-A71 seriously endangers children’s health. Although autophagy is an important antiviral defense mechanism, some viruses have evolved strategies to utilize autophagy to promote self-replication. EV-A71 can utilize autophagy vesicles as replication scaffolds, indicating that EV-A71 infection is closely related to its autophagy induction mechanism. VP1, a structural protein of EV-A71, has been reported to induce autophagy, but the underlying mechanism is still unclear. In this study, we found that the C-terminus (aa 251–297) of VP1 induces autophagy. Mass spectrometry analysis suggested that prohibitin 2 (PHB2) interacts with the C-terminus of the EV-A71 VP1 protein, and this was further verified by coimmunoprecipitation assays. After PHB2 knockdown, EV-A71 replication, viral particle release, and viral protein synthesis were reduced, and autophagy was inhibited. The results suggest that PHB2 interaction with VP1 is essential for induction of autophagy and the infectivity of EV-A71. Furthermore, we confirmed that EV-A71 induced complete autophagy that required autolysosomal acidification, thus affecting EV-A71 infection. In summary, this study revealed that the host protein PHB2 is involved in an autophagy mechanism during EV-A71 infection.

The function of apolipoproteins L (APOLs): relevance for kidney disease, neurotransmission disorders, cancer and viral infection

“…Indeed, mAPOL9 interacts with PHB [137] and PHB are present in APOL1 and APOL3 immunoprecipitates ([8] and Uzureau S & Pays E, unpublished). PHB are mainly found in the mitochondrial inner membrane, where they interact with cardiolipin and promote mitochondrial fusion [162], while also behaving as receptors for mitophagy [138] and inducing autophagy upon interaction with some viruses [139] (review in Ref. [163]), all features evoking APOL1 and APOL3 characteristics.…”

“…Therefore, in macrophages PHB could be involved in the APOL1 restriction of HIV‐1 replication, which results from increased endolysosomal protein degradation resembling autophagy [9]. Conversely, PHB 2 was found to favour infection by Enterovirus A71 through the formation of autophagy vesicles acting as replication scaffolds [139]. Thus, the autophagy‐linked activities of PHB 2 exerted opposed effects on infection by two different picornaviruses, TMEV and Enterovirus A71 [137,139].…”

“…Conversely, PHB 2 was found to favour infection by Enterovirus A71 through the formation of autophagy vesicles acting as replication scaffolds [139]. Thus, the autophagy‐linked activities of PHB 2 exerted opposed effects on infection by two different picornaviruses, TMEV and Enterovirus A71 [137,139]. PHB also promoted infection by other viruses such as the DENV‐2 flavivirus and Chikungunya togavirus [140,141].…”

Dysregulated autophagy contributes to the pathogenesis of enterovirus A71 infection

“…NH 4 Cl treatment markedly increases VP0 abundance, indicating that acidification inhibition suppresses the cleavage of capsid protein to generate mature virus [ 62 ]. Prohibitin 2 directs EVA71 infection (intracellular EVA71 RNA and supernatants viral titers) as partially dependent on the acidification of autolysosomes [ 75 ]. However, the question remains of whether acidic vesicles directly affect EVA71 uncoating or maturation or both.…”

“…Prohibitin 2, an inner mitochondrial membrane protein from the prohibitin protein family, is a mitophagy receptor mediating mitochondria for autophagic degradation [ 104 ]. A recent study reported that the C-terminus (aa 251–297) of EVA71 VP1 contributes to an increasing LC3-II/LC3-I ratio through interaction with prohibitin 2 [ 75 ], indicating that EVA71 may promote autophagy activity via prohibitin 2. In turn, prohibitin 2 directed EVA71 infection (intracellular EVA71 RNA and supernatants viral titers) in a manner partly dependent on the acidification of autolysosomes, which is involved in the complete autophagy induction [ 75 ].…”