title: TRIM22 inhibits influenza A virus infection by targeting the viral nucleoprotein for degradation.
abstract: Tripartite motif (TRIM) protein superfamily members are emerging as important effectors of the innate immune response against viral infections. In particular, TRIM22 was reported to exert antiviral activity against RNA viruses, such as hepatitis B virus (HBV), encephalomyocarditis virus (ECMV), and human immunodeficiency virus type 1 (HIV-1). We demonstrate here, for the first time, that TRIM22 is upregulated by influenza A virus (IAV) infection at both mRNA and protein levels in human alveolar epithelial A549 cells. Conversely, TRIM22 potently restricted IAV replication, in that prevention of TRIM22 expression by means of short hairpin RNA led to a 10-fold enhancement of IAV replication in these cells. Depletion of TRIM22 also reduced the anti-IAV activity of alpha interferon (IFN-α), suggesting that TRIM22 is an important IFN-stimulated gene that is required for maximal suppression of IAV by type I IFN. Furthermore, the IAV infectious titer decreased up to 100-fold in MDCK cells expressing exogenous human TRIM22. Restriction of IAV replication was accounted for by the interaction between TRIM22 and the viral nucleoprotein (NP), resulting in its polyubiquitination and degradation in a proteasome-dependent manner. Thus, TRIM22 represents a novel restriction factor upregulated upon IAV infection that curtails its replicative capacity in epithelial cells.
authors: Viral Pathogens and Biosafety Unit, Division of Immunology, Transplantation and Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy.
authors: Andrea
authors: A
authors: Di Pietro
authors: Anna
authors: A
authors: Kajaste-Rudnitski
authors: Alexandra
authors: A
authors: Oteiza
authors: Lucia
authors: L
authors: Nicora
authors: Greg J
authors: GJ
authors: Towers
authors: Nadir
authors: N
authors: Mechti
authors: Elisa
authors: E
authors: Vicenzi
mesh_terms: D000818:Animals; D002460:Cell Line; D004285:Dogs; D004847:Epithelial Cells / Q000276:immunology / Q000821:virology; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D054884:Host-Pathogen Interactions; D006801:Humans; D009980:Influenza A virus / Q000276:immunology* / Q000502:physiology; D015778:Minor Histocompatibility Antigens; D019590:Nucleocapsid Proteins; D059748:Proteolysis; D016601:RNA-Binding Proteins / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism*; D000070584:Tripartite Motif Proteins; D015854:Up-Regulation; D014758:Viral Core Proteins / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D015778:Minor Histocompatibility Antigens; C048842:NP protein, Influenza A virus; D019590:Nucleocapsid Proteins; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; C094314:TRIM22 protein, human; D000070584:Tripartite Motif Proteins; D014758:Viral Core Proteins