PARP1 Enhances Influenza A Virus Propagation by Facilitating Degradation of Host Type I Interferon Receptor.

Influenza A virus (IAV) utilizes multiple strategies to confront or evade host type I interferon (IFN)-mediated antiviral responses in order to enhance its own propagation within the host. One such strategy is to induce the degradation of type I IFN receptor 1 (IFNAR1) by utilizing viral hemagglutinin (HA). However, the molecular mechanism behind this process is poorly understood. Here, we report that a cellular protein, poly(ADP-ribose) polymerase 1 (PARP1), plays a critical role in mediating IAV HA-induced degradation of IFNAR1. We identified PARP1 as an interacting partner for IAV HA through mass spectrometry analysis. This interaction was confirmed by coimmunoprecipitation analyses. Furthermore, confocal fluorescence microscopy showed altered localization of endogenous PARP1 upon transient IAV HA expression or during IAV infection. Knockdown or inhibition of PARP1 rescued IFNAR1 levels upon IAV infection or HA expression, exemplifying the importance of PARP1 for IAV-induced reduction of IFNAR1. Notably, PARP1 was crucial for the robust replication of IAV, which was associated with regulation of the type I IFN receptor signaling pathway. These results indicate that PARP1 promotes IAV replication by controlling viral HA-induced degradation of host type I IFN receptor. Altogether, these findings provide novel insight into interactions between influenza virus and the host innate immune response and reveal a new function for PARP1 during influenza virus infection.IMPORTANCE Influenza A virus (IAV) infections cause seasonal and pandemic influenza outbreaks, which pose a devastating global health concern. Despite the availability of antivirals against influenza, new IAV strains continue to persist by overcoming the therapeutics. Therefore, much emphasis in the field is placed on identifying new therapeutic targets that can more effectively control influenza. IAV utilizes several tactics to evade host innate immunity, which include the evasion of antiviral type I interferon (IFN) responses. Degradation of type I IFN receptor (IFNAR) is one known method of subversion, but the molecular mechanism for IFNAR downregulation during IAV infection remains unclear. Here, we have found that a host protein, poly(ADP-ribose) polymerase 1 (PARP1), facilitates IFNAR degradation and accelerates IAV replication. The findings reveal a novel cellular target for the potential development of antivirals against influenza, as well as expand our base of knowledge regarding interactions between influenza and the host innate immunity.

Disulfiram with Cu2+ alleviates dextran sulfate sodium-induced ulcerative colitis in mice.

Background: Disulfiram (DSF), a Food and Drug Administration (FDA)-approved drug for chronic alcohol addiction, has anti-inflammatory effects that help prevent various cancers, and Cu2+ can enhance the effects of DSF. Inflammatory bowel diseases (IBD) are characterized by chronic or recurrent relapsing gastrointestinal inflammation. Many drugs targeting the immune responses of IBD have been developed, but their application has many problems, including side effects and high costs. Therefore, there is an urgent need for new drugs. In this study, we investigated the preventive effects of DSF+Cu2+ on dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) in mice. Methods: The anti-inflammatory effects were investigated using the DSS-induced colitis mouse model and lipopolysaccharide (LPS)-induced macrophages. DSS-induced TCRß-/- mice were used to demonstrate the effect of DSF in conjunction with Cu2+ on CD4+ T cell-secreted interleukin 17 (IL-17). In addition, the effect of DSF+Cu2+ on intestinal flora was studied by 16S rRNA microflora sequencing. Results: DSF and Cu2+ could significantly reverse the symptom of DSS-induced UC in mice, such as weight loss, disease activity index score, colon length shortening, and reversal of colon pathological changes. DSF and Cu2+ could inhibit colonic macrophage activation by blocking the nuclear factor kappa B (NF-κB) pathway, reducing nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain-containing 3 (NLRP3)-inflammasome-derived interleukin 1 beta (IL-1ß) secretion and caspase-1 (CASP1) activation, and decreasing IL-17 secretion by CD4+ T cells. Moreover, the treatment of DSF and Cu2+ could protect the intestinal barrier by reversing the expression of tight junction proteins, zonula occluden-1 (ZO-1), occludin, and mucoprotein-2 (MUC2). Additionally, DSF+Cu2+ could reduce the abundance of harmful bacteria and increase beneficial bacteria in the intestinal tract of mice, effectively improving intestinal microecology. Conclusion: Our study evaluated the effect of DSF+Cu2+ on the immune system and gut microbiota in colonic inflammation and highlighted its potential to treat UC in the clinic.

p300 promotes cell proliferation through suppressing Kaposi's sarcoma-associated herpesvirus (KSHV) reactivation in the infected B-lymphoma cells.

Primary Effusion Lymphoma (PEL) is a B-cell lymphoma associated with Kaposi's sarcoma herpesvirus (KSHV) infection. However, the mechanism of oncogenesis of PEL is still unclear. Studies have shown that the cellular transcriptional coactivator p300 regulates the interaction between host and virus, which plays a vital role in viral replication. In this study, we investigated the role of p300 in BCBL1 cells during the KSHV life cycle. We found that p300 knockout resulted in an overall increase for the early lytic genes and changed the expression of genes associated with tumor development, proliferation, and the immune response in the KSHV infected B cells. However, knockout of p300 significantly inhibited the expression of the immediate-early gene RTA and the late lytic gene K8 after KSHV lytic activation. Additionally, the intracellular KSHV genome copy number and the virion production were reduced. These results demonstrated that p300 plays a crucial role in suppressing KSHV viral replication in BCBL1. Furthermore, we observed that the growth of BCBL1 was inhibited by knockout of p300, which confirmed our findings that p300 promotes cell proliferation. This study further provided evidence that p300 plays an important role in the pathogenesis of BCBL1, which might lead to the oncogenesis of PEL caused by KSHV infection.

A versatile assay for alkaline phosphatase detection based on thymine-HgII-thymine structure generation mediated by TdT.

Alkaline phosphatase (ALP) is a vital hydrolysis enzyme in phosphate metabolism, which catalyzes the hydrolysis of phosphate ester groups in proteins, nucleic acids, and other small molecules. Meanwhile, abnormal ALP expression is associated with occurrence and development of many diseases. Terminal deoxynucleotidyl transferase (TdT) is a widely used tool enzyme in many fields, which randomly adds deoxyribonucleoside triphosphates (dNTPs) at the 3'-OH termini of ssDNA in a template-free manner. In this work, we designed a versatile, convenient, label-free, and highly sensitive fluorescence enhancing assay for ALP activity detection based on the characteristics of ALP, TdT, and thymine-HgII-thymine (T-Hg2+-T) structure. In the presence of ALP, the 3'-phosphoryl end of the ssDNA-p was hydrolyzed to hydroxyl group, followed by addition of a poly-T tail on its 3' terminal hydroxyl in the mixing solution containing both TdT and dTTPs. Then, the DNA with poly-T tail could interact with Hg2+ to form the stable T-Hg2+-T mediated metallo DNA duplex, which enhanced the fluorescence intensity of the SG. Under optimal conditions, the proposed system was employed for quantitatively monitoring ALP activity with a dynamic range of 0-2500 mU mL-1, and the actual detection limit could be down to 0.025 mU mL-1. And the determination of ALP activity in human serum samples and MCF-7 cells lysates exhibited a good sensing performance, demonstrating its potential applications in biochemical research and clinical diagnosis. Meanwhile, this system could also be applied to both TdT and Hg2+ detection.