Nc886, a Novel Suppressor of the Type I Interferon Response Upon Pathogen Intrusion.

Interferons (IFNs) are a crucial component in the innate immune response. Especially the IFN-ß signaling operates in most cell types and plays a key role in the first line of defense upon pathogen intrusion. The induction of IFN-ß should be tightly controlled, because its hyperactivation can lead to tissue damage or autoimmune diseases. Activation of the IFN-ß promoter needs Interferon Regulatory Factor 3 (IRF3), together with Nuclear Factor kappa-light-chain-enhancer of activated B cells (NF-κB) and Activator Protein 1 (AP-1). Here we report that a human noncoding RNA, nc886, is a novel suppressor for the IFN-ß signaling and inflammation. Upon treatment with several pathogen-associated molecular patterns and viruses, nc886 suppresses the activation of IRF3 and also inhibits NF-κB and AP-1 via inhibiting Protein Kinase R (PKR). These events lead to decreased expression of IFN-ß and resultantly IFN-stimulated genes. nc886's role might be to restrict the IFN-ß signaling from hyperactivation. Since nc886 expression is regulated by epigenetic and environmental factors, nc886 might explain why innate immune responses to pathogens are variable depending on biological settings.

A host non-coding RNA, nc886, plays a pro-viral role by promoting virus trafficking to the nucleus.

Elucidation of the interplay between viruses and host cells is crucial for taming viruses to benefit human health. Cancer therapy using adenovirus, called oncolytic virotherapy, is a promising treatment option but is not robust in all patients. In addition, inefficient replication of human adenovirus in mouse hampered the development of an in vivo model for preclinical evaluation of therapeutically engineered adenovirus. nc886 is a human non-coding RNA that suppresses Protein Kinase R (PKR), an antiviral protein. In this study, we have found that nc886 greatly promotes adenoviral gene expression and replication. Remarkably, the stimulatory effect of nc886 is not dependent on its function to inhibit PKR. Rather, nc886 facilitates the nuclear entry of adenovirus via modulating the kinesin pathway. nc886 is not conserved in mouse and, when xenogeneically expressed in mouse cells, promotes adenovirus replication. Our investigation has discovered a novel mechanism of how a host ncRNA plays a pro-adenoviral role. Given that nc886 expression is silenced in a subset of cancer cells, our study highlights that oncolytic virotherapy might be inefficient in those cells. Furthermore, our findings open future possibilities of harnessing nc886 to improve the efficacy of oncolytic adenovirus and to construct nc886-expressing transgenic mice as an animal model.