In invertebrates, small interfering RNAs are at the vanguard of cell-autonomous antiviral immunity. In contrast, antiviral mechanisms initiated by interferon (IFN) signaling predominate in mammals. Whilst mammalian IFN-induced miRNA are known to inhibit specific viruses, it is not known whether host-directed microRNAs, downstream of IFN-signaling, have a role in mediating broad antiviral resistance. By performing an integrative, systematic, global analysis of RNA turnover utilizing 4-thiouridine labeling of newly transcribed RNA and pri/pre-miRNA in IFN-activated macrophages, we identify a new post-transcriptional viral defense mechanism mediated by miR-342-5p. On the basis of ChIP and site-directed promoter mutagenesis experiments, we find the synthesis of miR-342-5p is coupled to the antiviral IFN response via the IFN-induced transcription factor, IRF1. Strikingly, we find miR-342-5p targets mevalonate-sterol biosynthesis using a multihit mechanism suppressing the pathway at different functional levels: transcriptionally via SREBF2, post-transcriptionally via miR-33, and enzymatically via IDI1 and SC4MOL. Mass spectrometry-based lipidomics and enzymatic assays demonstrate the targeting mechanisms reduce intermediate sterol pathway metabolites and total cholesterol in macrophages. These results reveal a previously unrecognized mechanism by which IFN regulates the sterol pathway. The sterol pathway is known to be an integral part of the macrophage IFN antiviral response, and we show that miR-342-5p exerts broad antiviral effects against multiple, unrelated pathogenic viruses such Cytomegalovirus and Influenza A (H1N1). Metabolic rescue experiments confirm the specificity of these effects and demonstrate that unrelated viruses have differential mevalonate and sterol pathway requirements for their replication. This study, therefore, advances the general concept of broad antiviral defense through multihit targeting of a single host pathway.

HighlightsIFN-γ leads to the proteasomal degradation of HMGCR.IFN-γ and 25-HC can transcriptionally and post-translationally alter levels of HMGCR.The reduction of HMGCR through the action of IFN-γ requires the de novo synthesis of 25-HC by CH25H.

Building on recent digital literacy initiatives, three strategies were identified for exploration, relating to successful use of digital tablets by older adults who lacked previous experience. The questions under investigation were: What are the implications of one-to-one support for self-efficacy and promoting attendance at digital literacy sessions? Could free tablets assist in overcoming economic and social barriers to participation? By what means could age-related physical problems with digital technology be combated? Method Between June and July 2016, eight older adults (five men and three women aged 70 to 87) attended a six-week course in digital literacy, supported by four volunteer tutors. Tablets were loaned to participants who did not own a device. A variety of accessories, such as styluses and hard cases, were discussed and shared. Results and discussion Weekly attendance was almost 100%, with no participants withdrawing from the course, and only occasional absences due to other commitments. The group displayed a wide spectrum of ability, from complete beginners to regular computer users, although all participants initially rated themselves as unconfident in relation to tablets. By the end of the course, self-efficacy had increased from 44% to 71%. Accessories proved popular with a number of participants, particularly for those with fine motor control issues. Conclusion Teams of tutors may promote attendance in comparison to lone-tutor-led classes or peer learning scenarios, and have the potential to impact positively on perceptions of self-efficacy. For older adults, particularly those from areas of multiple deprivations, access to free or borrowed devices may be key to participation, although a lack of access to home broadband can reduce ability to practice new skills between sessions. Modern capacitive screens offer reduced haptic feedback by comparison with the resistive screens on older mobile devices, leading some older adults to require further accessories in order to engage successfully with tablet computers.

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Previous studies have demonstrated that the product of the Interferon stimulated gene Ch25h, 25-Hydroxycholestrol, provides an immediate and rapid mechanism for down-regulating sterol biosynthesis, through the inhibition of Hmgcr gene expression and proteolytic degradation of HMGCR protein. Further studies provide evidence that inhibition of the sterol biosynthesis pathway by 25-HC has broad antiviral effects. In this study, Influenza A virus (IAV) replication was inhibited in cells treated with Fluvastatin or where Hmgcr expression was inhibited with an siRNA. Treatment of A549 cells with 25-HC however, resulted in a 2-fold enhancement of IAV replication despite the fact that 25-HC promotes the proteolytic degradation of HMGCR. A549 cells infected with IAV revealed a rapid loss of HMGCR protein, a reduction in Hmgcr gene expression as well as an increase in the expression of Ch25h, that were all independent of the IFN pathway.Infection of both wild-type and Ch25h -/murine BMDMs with IAV also revealed a rapid loss of HMGCR abundance indicating that 25-HC independent mechanisms exist for promoting proteolytic degradation of HMGCR. These data for the human A549 cell line contrast with the induction of Ch25h and subsequent loss of HMGCR in murine cells that has been shown to be dependent on IFN signalling.