A critical role for MSR1 in vesicular stomatitis virus infection of the central nervous system

Leishmania regulates host YY1: Comparative proteomic analysis identifies infection modulated YY1 dependent proteins

The protein Yin-Yang 1 (YY1) is a ubiquitous multifunctional transcription factor. Interestingly, there are several cellular functions controlled by YY1 that could play a role in Leishmania pathogenesis. Leishmaniasis is a human disease caused by protozoan parasites of the genus Leishmania. This study examined the potential role of macrophage YY1 in promoting Leishmania intracellular survival. Deliberate knockdown of YY1 resulted in attenuated survival of Leishmania in infected macrophages, suggesting a role of YY1 in Leishmania persistence. Biochemical fractionation studies revealed Leishmania infection caused redistribution of YY1 to the cytoplasm from the nucleus where it is primarily located. Inhibition of nuclear transport by leptomycin B attenuates infection-mediated YY1 redistribution and reduces Leishmania survival. This suggests that Leishmania induces the translocation of YY1 from the nucleus to the cytoplasm of infected cells, where it may regulate host molecules to favour parasite survival. A label-free quantitative whole proteome approach showed that the expression of a large number of macrophage proteins was dependent on the YY1 level. Interestingly, several of these proteins were modulated in Leishmania-infected cells, revealing YY1-dependent host response and suggesting their potential role in Leishmania pathogenesis. Together, this study identifies YY1 as a novel virulence factor that promotes Leishmania survival inside host macrophages.

Dietary Flavonoid Quercetin Supplement Promotes Antiviral Innate Responses Against Vesicular Stomatitis Virus Infection by Reshaping the Bacteriome and Host Metabolome in Mice

SCOPE

Active ingredients in functional foods exhibit broad-spectrum antiviral activity. The objective of this study is to investigate the protective effect of quercetin derived from bee propolis, a natural product with antiviral activity and modulating effects on the gut microbiota, against vesicular stomatitis virus (VSV) infection.

METHODS AND RESULTS

Through a cellular-based study, this study demonstrates that quercetin can modulate the activity of interferon-regulating factor 3 (IRF3). In vivo, it shows that quercetin protects mice from VSV infection by enhancing interferon production and inhibiting the production of proinflammatory cytokines. The study conducts 16S rRNA-based gut microbiota and nontargets metabolomics analyses to elucidate the mechanisms underlying quercetin-mediated bidirectional communication between the gut microbiome and host metabolome during viral infection. Quercetin not only ameliorates VSV-induced dysbiosis of the intestinal flora but also alters serum metabolites related to lipid metabolism. Cross-correlations between the gut bacteriome and the serum metabolome indicate that quercetin can modulate phosphatidylcholine (16:0/0:0) and 5-acetylamino-6-formylamino-3-methyluracil to prevent VSV infection.

CONCLUSION

This study systematically elucidates the anti-VSV mechanism of quercetin through gut bacteriome and host metabolome assays, offering new insights into VSV treatment and revealing the mechanisms behind a novel disease management strategy using dietary flavonoid supplements.

UBR5 promotes antiviral immunity by disengaging the transcriptional brake on RIG-I like receptors

The Retinoic acid-Inducible Gene I (RIG-I) like receptors (RLRs) are the major viral RNA sensors essential for the initiation of antiviral immune responses. RLRs are subjected to stringent transcriptional and posttranslational regulations, of which ubiquitination is one of the most important. However, the role of ubiquitination in RLR transcription is unknown. Here, we screen 375 definite ubiquitin ligase knockout cell lines and identify Ubiquitin Protein Ligase E3 Component N-Recognin 5 (UBR5) as a positive regulator of RLR transcription. UBR5 deficiency reduces antiviral immune responses to RNA viruses, while increases viral replication in primary cells and mice. Ubr5 knockout mice are more susceptible to lethal RNA virus infection than wild type littermates. Mechanistically, UBR5 mediates the Lysine 63-linked ubiquitination of Tripartite Motif Protein 28 (TRIM28), an epigenetic repressor of RLRs. This modification prevents intramolecular SUMOylation of TRIM28, thus disengages the TRIM28-imposed brake on RLR transcription. In sum, UBR5 enables rapid upregulation of RLR expression to boost antiviral immune responses by ubiquitinating and de-SUMOylating TRIM28.

The role of macrophage scavenger receptor 1 (MSR1) in inflammatory disorders and cancer

Macrophage scavenger receptor 1 (MSR1), also named CD204, holds key inflammatory roles in multiple pathophysiologic processes. Present primarily on the surface of various types of macrophage, this receptor variably affects processes such as atherosclerosis, innate and adaptive immunity, lung and liver disease, and more recently, cancer. As highlighted throughout this review, the role of MSR1 is often dichotomous, being either host protective or detrimental to the pathogenesis of disease. We will discuss the role of MSR1 in health and disease with a focus on the molecular mechanisms influencing MSR1 expression, how altered expression affects disease process and macrophage function, the limited cell signalling pathways discovered thus far, the emerging role of MSR1 in tumour associated macrophages as well as the therapeutic potential of targeting MSR1.