Phosphorylation of JIP4 at S730 presents anti-viral properties against influenza A virus infection

Abstract

Influenza A virus (IAV) is the causative agent of flu disease that results in annual epidemics and occasional pandemics. IAV alters several signaling pathways of the cellular host response in order to promote its replication. Therefore, our group investigates different host cell pathways modified in IAV infection as promising targets for long-lasting therapeutic approaches. Here, we show that c-Jun NH2-terminal kinase (JNK)-interacting protein (JIP) 4 is dynamically phosphorylated in IAV infection. Lack of JIP4 resulted in higher virus titers with significant differences in viral protein and mRNA accumulation as early as within the first replication cycle. In accordance, decreased IAV titers and protein accumulation was observed during overexpression of JIP4. Strikingly, the anti-viral function of JIP4 does neither originate from a modulation of JNK or p38 MAPK pathways, nor from altered expression of interferons or interferon-stimulated genes, but rather from a direct reduction of viral polymerase activity. Furthermore, interference of JIP4 with IAV replication is linked to phosphorylation of the serine at position 730, that is sufficient to impede with the viral polymerase and is mediated by the Raf/MEK/ERK pathway. Collectively, we provide evidence that JIP4, a host protein modulated in IAV infection, exhibits anti-viral properties that are dynamically controlled by its phosphorylation at S730.