PRMT2 silencing regulates macrophage polarization through activation of STAT1 or inhibition of STAT6.

BACKGROUND: Macrophages play significant roles in innate immune responses and are heterogeneous cells that can be polarized into M1 or M2 phenotypes. PRMT2 is one of the type I protein arginine methyltransferases involved in inflammation. However, the role of PRMT2 in M1/M2 macrophage polarization remains unclear. Our study revealed the effect and mechanism of PRMT2 in macrophage polarization. METHODS: Bone marrow-derived macrophages (BMDMs) were polarized to M1 or M2 state by LPS plus murine recombinant interferon-γ (IFN-γ) or interleukin-4 (IL-4). Quantitative polymerase chain reaction (qPCR), western blot and flow cytometry (FCM) assay were performed and analyzed markers and signaling pathways of macrophage polarization. RESULTS: We found that PRMT2 was obviously upregulated in LPS/IFN-γ-induced M1 macrophages, but it was little changed in IL-4-induced M2 macrophages. Furthermore, PRMT2 konckdown increased the expression of M1 macrophages markers through activation of STAT1 and decreased the expression of M2 macrophages markers through inhibition of STAT6. CONCLUSIONS: PRMT2 silencing modulates macrophage polarization by activating STAT1 to promote M1 and inhibiting STAT6 to attenuate the M2 state.

GNAQ Negatively Regulates Antiviral Innate Immune Responses in a Calcineurin-Dependent Manner.

Although guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) constitute the largest cell surface membrane receptor family and transduce thousands of extracellular signals into the cytoplasm, only four kinds of G protein α subunits (Gαs, Gαi/o, Gαq/11, and Gα12/13) are coupled to regulate cAMP or phosphatidylinositol signals. Growing evidence suggests that viruses tend to hijack GPCRs and harness their activated intracellular signaling pathways. Thus, understanding the roles of G protein signaling will further uncover the GPCR signaling pathways that are exploited by viruses. In this study, we demonstrate that the expression of GNAQ (Gq α subunit) was downregulated during viral infection and that small interfering RNA-mediated GNAQ knockdown protected host cells from both vesicular stomatitis virus (VSV) and HSV type 1 infection. Meanwhile, VSV and HSV type 1 replication was reduced significantly in Gnaq-deficient macrophages. Accordingly, the VSV distribution in the liver, spleen, and lung was reduced in Gnaq-deficient mice during VSV infection, and Gnaq-deficient mice were much more resistant to VSV infection than wild-type mice. Mechanistically, GNAQ limits type I IFN production through the canonical PLC-ß/Ca2+/CALNA signaling pathway, which has been demonstrated to dephosphorylate virus-activated TANK-binding kinase 1 (TBK1). Thus, our data demonstrate that GNAQ negatively regulates the antiviral innate immune responses in a calcineurin-dependent manner. These findings also provide insights into the function and cross-talk of the classic GPCR signaling pathway with antiviral innate immune responses and suggest a potential therapeutic role for GNAQ in controlling viral diseases.

Virus-Triggered ATP Release Limits Viral Replication through Facilitating IFN-ß Production in a P2X7-Dependent Manner.

Accumulating evidence shows that innate immune responses are associated with extracellular nucleotides, particularly ATP. In this article, we demonstrate extensive protection of ATP/P2X7 signaling in a host against viral infection. Interestingly, we observed a significant increase in ATP as a danger signal in vesicular stomatitis virus (VSV)-infected cell supernatant and VSV-infected mice in an exocytosis- and pannexin channel-dependent manner. Furthermore, extracellular ATP reduces the replication of VSV, Newcastle disease virus, murine leukemia virus, and HSV in vivo and in vitro through the P2X7 receptor. Meanwhile, ATP significantly increases IFN-ß expression in a concentration- and time-dependent manner. Mechanistically, ATP facilitates IFN-ß secretion through P38/JNK/ATF-2 signaling pathways, which are crucial in promoting antiviral immunity. Taken together, these results demonstrate the protective role of extracellular ATP and P2X7 in viral infection and suggest a potential therapeutic role for ATP/P2X7 in viral diseases.

Leucine-rich repeat-containing G protein-coupled receptor 4 facilitates vesicular stomatitis virus infection by binding vesicular stomatitis virus glycoprotein.

Vesicular stomatitis virus (VSV) and rabies and Chandipura viruses belong to the Rhabdovirus family. VSV is a common laboratory virus to study viral evolution and host immune responses to viral infection, and recombinant VSV-based vectors have been widely used for viral oncolysis, vaccination, and gene therapy. Although the tropism of VSV is broad, and its envelope glycoprotein G is often used for pseudotyping other viruses, the host cellular components involved in VSV infection remain unclear. Here, we demonstrate that the host protein leucine-rich repeat-containing G protein-coupled receptor 4 (Lgr4) is essential for VSV and VSV-G pseudotyped lentivirus (VSVG-LV) to infect susceptible cells. Accordingly, Lgr4-deficient mice had dramatically decreased VSV levels in the olfactory bulb. Furthermore, Lgr4 knockdown in RAW 264.7 cells also significantly suppressed VSV infection, and Lgr4 overexpression in RAW 264.7 cells enhanced VSV infection. Interestingly, only VSV infection relied on Lgr4, whereas infections with Newcastle disease virus, influenza A virus (A/WSN/33), and herpes simplex virus were unaffected by Lgr4 status. Of note, assays of virus entry, cell ELISA, immunoprecipitation, and surface plasmon resonance indicated that VSV bound susceptible cells via the Lgr4 extracellular domain. Pretreating cells with an Lgr4 antibody, soluble LGR4 extracellular domain, or R-spondin 1 blocked VSV infection by competitively inhibiting VSV binding to Lgr4. Taken together, the identification of Lgr4 as a VSV-specific host factor provides important insights into understanding VSV entry and its pathogenesis and lays the foundation for VSV-based gene therapy and viral oncolytic therapeutics.

Elimination of GPR146-mediated antiviral function through IRF3/HES1-signalling pathway.

As the most important host defence against viral infection, interferon (IFN) stimulates hundreds of antiviral genes (ISGs) that together establish an 'antiviral state'. However, the antiviral function of most ISGs in viral infection still need further exploration. Here, we demonstrated that the expression of G-protein-coupled receptor 146 (GPR146) is highly increased by both IFN-ß and IFN-γ in a signal transducer and activator of transcription 1-dependent signalling pathway. Most importantly, overexpression of GPR146 protects the host cells from vesicular stomatitis virus and Newcastle disease virus infection but not from infection by herpes simplex virus. In contrast, the virus-induced IFN-ß production changed little in Gpr146-knockout cells. Furthermore, the Gpr146-deficient mice showed similar susceptibility to wild-type mice with vesicular stomatitis virus infection. Interestingly, the expression of GPR146 in virus-infected cells was strikingly reduced and can partially explain why the viral infection was little influenced in Gpr146-knockout mice. Surprisingly, virus-activated IFN regulatory factor 3 (IRF3) signalling not only induces the expression of IFN but also represses GPR146 expression through HES1 (hairy and enhancer of split-1)-mediated transcriptional activity to establish a dynamic equilibrium between pro-viral and antiviral stages in host cells. Taken together, these data reveal the antiviral role of GPR146 in fighting viral infection although the GPR146-mediated protection is eliminated by IRF3/HES1-signalling, which suggests a potential therapeutic significance of both GPR146 and HES1 signalling in viral infection.

Research progress on the correlation between platelet aggregation and tumor progression.

Platelets are generally considered as the main functional unit of the coagulation system. However, more and more studies have confirmed that platelets also have an important relationship with tumor progression. Tumor cells can utilize platelets to promote their own infiltration and hematogenous metastasis, and platelets are activated and aggregated in this process. Therefore, platelet aggregation may be a concomitant marker of tumor progression. This is of great significance for predicting tumor metastasis before timely treatments.

Construction of mitochondrial-targeting nano-prodrug for enhanced Rhein delivery and treatment for osteoarthritis in vitro.

Rhein, a natural anthraquinone compound derived from traditional Chinese medicine, exhibits potent anti-inflammatory properties via modulating the level of Reactive oxygen or nitrogen species (RONS). Nevertheless, its limited solubility in water, brief duration of plasma presence, as well as its significant systemic toxicity, pose obstacles to its in vivo usage, necessitating the creation of a reliable drug delivery platform to circumvent these difficulties. In this study, an esterase-responsive and mitochondria-targeted nano-prodrug was synthesized by conjugating Rhein with the polyethylene glycol (PEG)-modified triphenyl phosphonium (TPP) molecule, forming TPP-PEG-RH, which could spontaneously self-assemble into RPT NPs when dispersed in aqueous media. The TPP outer layer of these nanoparticles enhances their pharmacokinetic profile, facilitates efficient delivery to mitochondria, and promotes cellular uptake, thereby enabling enhanced accumulation in mitochondria and improved therapeutic effects in vitro. The decline in RONS was observed in IL-1ß-stimulated chondrocyte after RPT NPs treating. RPT NPs also exert excellent anti-inflammatory (IL-1ß, TNF-α, IL-6 and MMP-13) and antioxidative effects (Cat and Sod) via the Nrf2 signalling pathway, upregulation of cartilage related genes (Col2a1 and Acan). Moreover, RPT NPs shows protection of mitochondrial membrane potential and inhibition of chondrocyte apoptosis. Moreover, These findings suggest that the mitochondria-targeted polymer-Rhein conjugate may offer a therapeutic solution for patients suffering from chronic joint disorders, by attenuating the progression of osteoarthritis (OA).

A Self-Healing Gel with an Organic-Inorganic Network Structure for Mitigating Circulation Loss.

Lost circulation control remains a challenge in drilling operations. Self-healing gels, capable of self-healing in fractures and forming entire gel block, exhibit excellent resilience and erosion resistance, thus finding extensive studies in lost circulation control. In this study, layered double hydroxide, Acrylic acid, 2-Acrylamido-2-methylpropane sulfonic acid, and CaCl2 were employed to synthesize organic-inorganic nanocomposite gel with self-healing properties. The chemical properties of nanocomposite gels were characterized using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope, X-ray photoelectron spectroscopy and thermogravimetric analysis. layered double hydroxide could be dispersed and exfoliated in the mixed solution of Acrylic acid and 2-Acrylamido-2-methylpropane sulfonic acid, and the swelling behavior, self-healing time, rheological properties, and mechanical performance of the nanocomposite gels were influenced by the addition of layered double hydroxide and Ca2+. Optimized nanocomposite gel AC6L3, at 90 °C, exhibits only a self-healing time of 3.5 h in bentonite mud, with a storage modulus of 4176 Pa, tensile strength of 6.02 kPa, and adhesive strength of 1.94 kPa. In comparison to conventional gel, the nanocomposite gel with self-healing capabilities demonstrated superior pressure-bearing capacity. Based on these characteristics, the nanocomposite gel proposed in this work hold promise as a candidate lost circulation material.

Pt-Se Hybrid Nanozymes with Potent Catalytic Activities to Scavenge ROS/RONS and Regulate Macrophage Polarization for Osteoarthritis Therapy.

The activation of pro-inflammatory M1-type macrophages by overexpression of reactive oxygen species (ROS) and reactive nitrogen species (RONS) in synovial membranes contributes to osteoarthritis (OA) progression and cartilage matrix degradation. Here, combing Pt and Se with potent catalytic activities, we developed a hybrid Pt-Se nanozymes as ROS and RONS scavengers to exert synergistic effects for OA therapy. As a result, Pt-Se nanozymes exhibited efficient scavenging effect on ROS and RONS levels, leading to repolarization of M1-type macrophages. Furthermore, the polarization of synovial macrophages to the M2 phenotype inhibited the expression of pro-inflammatory factors and salvaged mitochondrial function in arthritic chondrocytes. In vivo results also suggest that Pt-Se nanozymes effectively suppress the early progression of OA with an Osteoarthritis Research International Association score reduction of 68.21% and 82.66% for 4 and 8 weeks, respectively. In conclusion, this study provides a promising strategy to regulate inflammatory responses by macrophage repolarization processes for OA therapeutic.

Carbon neutral contribution and regional differences of clean energy based on life cycle assessment.

Developing clean energy is an important strategy to achieve global carbon neutrality. In the entire life cycle industrial chain of clean energy systems, fossil energy was directly or indirectly consumed during the processes from raw material production to waste disposal stages. The energy consumed by clean energy construction differed across regions, resulting in various carbon neutrality contributions of clean energy in different regions. We used bibliometrics to sort out the energy consumption of clean energy construction in different regions, including photovoltaic power generation, wind power, hydropower, and other clean energy sources. By combining the loss of land to decrease carbon pool during the operation of clean energy, we analyzed the current research hotspots, development status and trends, and difference in carbon emissions, and summarized the carbon neutral contributions of different regions. The intensity of clean energy carbon emission in China was significantly lower than global mean value. The average intensity of carbon emission in China in the four fields of onshore wind power, offshore wind power, hydropower, and photovoltaic power was 28.8%, 18.2%, 10.1%, and 16.7% lower than global average, respectively. For further research on carbon neutrality of clean energy, it is important to establish a unified life cycle assessment system, put forward construction strategies according to geographical differences, carry out ecological benefit evaluation for clean energy, and establish a clean energy transmission network system.

A molecular dynamics study on adsorption mechanisms of polar, cationic, and anionic polymers on montmorillonite.

Adsorption of polymers on clay in aqueous solutions has wide applications in environmental, medical, and energy-related areas, but the interactions between polymers and clay under varied conditions are still not fully understood. In this study, we investigated the adsorption mechanisms of four polymers belonging to different categories, namely anionic poly(acrylic acid) (poly-AA), cationic poly(diallyldimethylammonium chloride) (poly-DADMAC), nonionic polyacrylamide (poly-AM), and the copolymer of AA and DADMAC (poly-AADADMAC). By using molecular dynamics simulations, we compared the desorption kinetics of these polymers at different temperatures and found that poly-AA and poly-AM have the weakest and strongest adsorption abilities, respectively. Polymer adsorptions are slightly more stable at higher pressures, and high salinity favors the adsorption of charged polymers. Further analysis suggests that the adsorption of anionic poly-AA is less stable than that of cationic poly-DADMAC because the latter is attracted to the negatively charged surface by direct coulombic forces, and poly-AM is stabilized by van der Waals forces and hydrogen bonds. This study provides insights on how to enhance the adsorption affinity of polymers on a clay surface and may help the design or improvement of polymer/clay nanocomposite materials.

ATAXIA TELANGIECTASIA MUTATED PROTECTS AGAINST LIPOPOLYSACCARIDE-INDUCED BLOOD-BRAIN BARRIER DISRUPTION BY REGULATING ATK/DRP1-MEDIATED MITOCHONDRIAL HOMEOSTASIS.

ABSTRACT: Background: Protein kinase ataxia telangiectasia mutated (ATM) regulates the function of endothelial cells and responds quickly to endotoxin. However, the function of ATM in lipopolysaccharide (LPS)-induced blood-brain barrier (BBB) disruption remains unknown. This study aimed to investigate the role and underlying mechanism of ATM in the regulation of the BBB function in sepsis. Methods: We used LPS to induce BBB disruption in vivo and to establish an in vitro model of cerebrovascular endothelial cells. Blood-brain barrier disruption was assessed by measuring Evans blue leakage and expression of vascular permeability regulators. To investigate the role of ATM, its inhibitor AZD1390 and clinically approved doxorubicin, an anthracycline that can activate ATM, were administered as scheduled. To explore the underlying mechanism, protein kinase B (AKT) inhibitor MK-2206 was administered to block the AKT/dynamin-related protein 1 (DRP1) pathway. Results: Lipopolysaccharide challenge induced significant BBB disruption, ATM activation, and mitochondrial translocation. Inhibiting ATM with AZD1390 aggravated BBB permeability as well as the following neuroinflammation and neuronal injury, while activation of ATM by doxorubicin abrogated these defects. Further results obtained in brain microvascular endothelial cells showed that ATM inhibition reduced the phosphorylation of DRP1 at serine (S) 637, promoted excessive mitochondrial fission, and resulted in mitochondrial malfunction. By activating ATM, doxorubicin increased the protein binding between ATM and AKT and promoted the phosphorylated activation of AKT at S473, which could directly phosphorylate DRP1 at S637 to repress excessive mitochondrial fission. Consistently, the protective role of ATM was abolished by the AKT inhibitor MK-2206. Conclusions: Ataxia telangiectasia mutated protects against LPS-induced BBB disruption by regulating mitochondrial homeostasis, at least in part, through the AKT/DRP1 pathway.

Huge Primary Intermediate-grade Myofibroblastic Sarcoma in the Retroperitoneum.

Myofibroblastic sarcoma is exceedingly rare, with low-grade features in most cases, and rarely involves the retroperitoneum. The 2020 World Health Organization (WHO) classification of soft tissue tumours still lists only low-grade myofibroblastic sarcoma and shows no consensus on the definitions of high- and intermediate-grade myofibroblastic sarcomas, in contrast to the 2013 WHO classification. Surgical resection of the tumour and adjacent structures is the standard of care for most patients, and intermediate- and high-grade myofibroblastic sarcomas have very poor survival. We describe a patient with intermediate-grade myofibroblastic sarcoma in the retroperitoneum, who underwent en bloc resection and ureteroplasty without adjuvant therapy and was free of pain and any other discomfort during 19 months of follow-up. Key Words: Myofibroblastic sarcoma, Intermediate grade, Retroperitoneum, Surgery.

Effect of Temperature on the Corrosion Behavior and Corrosion Resistance of Copper-Aluminum Laminated Composite Plate.

In this paper, the effect of temperature on the corrosion behavior and corrosion resistance of the copper-aluminum laminated composite plates were investigated by salt-spray corrosion, potential polarization curve and electrochemical impedance spectroscopy. Moreover, the microstructure of the copper-aluminum laminated composite plate after salt-spray corrosion was observed by scanning electron microscope, and X-ray photoelectron spectroscopy was used to study the composition of corrosion product. The results revealed that the corrosion products of the copper-aluminum laminated composite plate were Al2O3 and AlOOH. Due to the galvanic corrosion of the copper-aluminum laminated composite plate, the cathode underwent oxygen absorption corrosion during the corrosion process; therefore, the presence of moisture and the amount of dissolved oxygen in the corrosive environment had a great influence on the corrosion process. The increasing temperature would evaporate a large amount of moisture, resulting in the corrosion product-aluminum oxide dehydrated and covered the surface of the material in the process of salt-spray corrosion, which played a role in protecting the material. Therefore, the corrosion resistance of the copper-aluminum laminated composite plate first decreased and then increased. In the salt-spray corrosion environment, the corrosion resistance of the copper-aluminum laminated composite plate reached the lowest at 45 °C, and its corrosion rate was the fastest, at 0.728 g/m2·h. The electrochemical corrosion occurred in the solution, and the impact was small; however, in addition to the protective corrosion products, the ion mobility in the solution also had a certain influence on the corrosion rate, and the ionic activity increased with the increase of temperature. Therefore, the corrosion resistance of the copper-aluminum laminated composite plate gradually decreased as the temperature increased, and its corrosion resistance was the worst at 50 °C.

Research on the Hot Deformation Behavior of the Casting NiTi Alloy.

The hot deformation behavior and processing maps of the casting NiTi alloy were studied at the deformation temperature of 650-1050 °C and the strain rate of 5 × 10-3-1 s-1 by Gleeble-3800 thermal simulating tester. The variation of the strain rate sensitivity exponent m and the activation energy Q under different deformation conditions (T = 650-1050 °C, ε˙ = 0.005-1 s-1) were obtained. The formability of the NiTi alloy was the best from 800 °C to 950 °C. The constitutive equation of the casting NiTi alloy was constructed by the Arrhenius model. The processing map of the casting NiTi alloy was plotted according to the dynamic material model (DMM) based on the Prasad instability criterion. The optimal processing areas were at 800-950 °C and 0.005-0.05 s-1. The microstructure of the casting NiTi alloy was analyzed by TEM, SEM and EBSD. The softening mechanisms of the casting NiTi alloy were mainly dynamic recrystallization of the Ti2Ni phase and the nucleation and growth of fine martensite.

Electrospinning preparation and anti-infrared radiation performance of silica/titanium dioxide composite nanofiber membrane.

Silica/titanium dioxide (SiO2/TiO2) composite nanofiber membranes with different TiO2 content were prepared with the technology of electrospinning using ethyl orthosilicate, butyl titanate and polyvinyl pyrrolidone as silicon titanium sources and spinning aids. TGA, XRD, SEM and FT-IR were used to analyze the thermal decomposition process, phase composition, microscopic morphology and infrared properties of the products. The study showed that with the increase of the calcination temperature, the TiO2 phase gradually changed from amorphous to anatase structure. Above 900 °C, a sample containing rutile TiO2 with a higher refractive index was obtained. Simultaneously, the continuity of the sample deteriorated, and the mechanical properties deteriorated. The study found that after calcination at 900 °C, the fiber membrane with a TiO2 content of 12% had the lowest cost and the best overall performance, with tensile strength being 3.09 MPa, and thermal conductivity at 500 °C being 0.0899 W m-1 K-1, which is 20% lower than that of pure SiO2 fiber membrane. This research provides a reference for the development of high temperature insulation materials with good flexibility.

Tumor-Derived Soluble MICA Obstructs the NKG2D Pathway to Restrain NK Cytotoxicity.

The natural killer group 2D (NKG2D) receptor and its ligands play important roles in immune surveillance. In this study, we observed that the average serum soluble MICA (sMICA) concentration of 174 hepatocellular carcinoma (HCC) patients was significantly higher than that in 80 healthy subjects (602.17 ± 338.15 vs. 72.26 ± 87.88 pg/ml, t = 3.107, P=0.002). The levels of serum sMICA in 44 HCC patients with initial levels above 400 pg/ml declined significantly after surgical removal of the liver cancer tissue (P<0.001). Moreover, the mean survival time of HCC patients who had sMICA above 400 pg/ml was significantly shorter than that HCC patients with lower sMICA levels (P<0.001). Using the reporter cell line (NKG2D-2B4) in which activation of the NKG2D receptor pathway results in GFP expression based on the stimulation of immobilized rMICA, we showed that the number of GFP-expressing cells decreased sharply in presence of sMICA. Upon adding sMICA, the release of cytokines IFN-γ, TNF-α, and IL-8 by NK cell line (NKL) under stimulation of immobilized rMICA was blocked. Using MICA-expressing cells as the target cells, we observed that about 80% of target cells were killed by NKL at E:T of 10:1, but in presence of sMICAhigh serum of HCC patients, the dead target cells were reduced to 30.8%. Compared in presence of sMICAlow serum from HCC patients, there were 63.7% of target cells dead (p=0.043). Thus, our data suggested that sMICA obstructs the activation of NKG2D pathway to protect tumor cells from NK cell-mediated cytotoxicity.

LncRNA HOXA-AS2 Facilitates Tumorigenesis and Progression of Papillary Thyroid Cancer by Modulating the miR-15a-5p/HOXA3 Axis.

The long non-coding RNA HOXA-AS2 has been found to be an oncogene in several types of human malignant tumors. However, its role in regulating the occurrence and development of papillary thyroid cancer (PTC) is still unclear. The present study investigated the function and mechanism(s) of HOXA-AS2 in PTC progression. Using quantitative real-time polymerase chain reaction, HOXA-AS2 was found to be differentially expressed in PTC tissues and cell lines. Kaplan-Meier analysis indicated that the overall survival rate of patients with higher levels of HOXA-AS2 was lower than those with relatively lower levels. Loss-of-function assays revealed that HOXA-AS2 knockdown inhibited PTC progression by inhibiting cellular proliferation, migration, and invasion and accelerating apoptosis. Mechanistically, loss-of-function assays showed a positive correlation between HOXA3 and HOXA-AS2 expression. Subcellular fractionation assay results revealed abundant HOXA-AS2 expression in the cytoplasm of PTC cells. Additionally, FOXD2-AS1 was found to upregulate HOXA3 expression by binding to miR-15a-5p. Finally, rescue assays demonstrated the overall function of the HOXA-AS2/miR-15a-5p/HOXA3 axis in PTC progression. These findings will significantly contribute to further research and the development of more efficient treatments for thyroid cancer in the future.

IFN-stimulated P2Y13 protects mice from viral infection by suppressing the cAMP/EPAC1 signaling pathway.

Among the most important sensors of extracellular danger signals, purinergic receptors have been demonstrated to play crucial roles in host defense against infection. However, the function of P2 receptors in viral infection has been little explored. Here we demonstrated that P2Y13 and its ligand ADP play an important role in protecting hosts from viral infections. First, we demonstrate that P2Y13, as a typical interferon-stimulated gene, is induced together with extracellular ADP during viral infection. Most importantly, extracellular ADP restricts the replication of different kinds of viruses, including vesicular stomatitis virus, Newcastle disease virus, herpes simplex virus 1, and murine leukemia virus. This kind of protection is dependent on P2Y13 but not P2Y1 or P2Y12, which are also considered as receptors for ADP. Furthermore, cyclic adenosine monophosphate and EPAC1 are downregulated by extracellular ADP through the P2Y13-coupled Gi alpha subunit. Accordingly, inhibition or deletion of EPAC1 significantly eliminates ADP/P2Y13-mediated antiviral activities. Taken together, our results show that P2Y13 and ADP play pivotal roles in the clearance of invaded virus and have the potential as antiviral targets.

Metabolite-Sensing G Protein Coupled Receptor TGR5 Protects Host From Viral Infection Through Amplifying Type I Interferon Responses.

The metabolite-sensing G protein-coupled receptors (GPCRs) bind to various metabolites and transmit signals that are important for proper immune and metabolic functions. However, the roles of metabolite-sensing GPCRs in viral infection are not well characterized. Here, we identified metabolite-sensing GPCR TGR5 as an interferon (IFN)-stimulated gene (ISG) which had increased expression following viral infection or IFN-ß stimulation in a STAT1-dependent manner. Most importantly, overexpression of TGR5 or treatment with the modified bile acid INT-777 broadly protected host cells from vesicular stomatitis virus (VSV), newcastle disease virus (NDV) and herpes simplex virus type 1 (HSV-1) infection. Furthermore, VSV and HSV-1 replication was increased significantly in Tgr5-deficient macrophages and the VSV distribution in liver, spleen and lungs was increased in Tgr5-deficient mice during VSV infection. Accordingly, Tgr5-deficient mice were much more susceptible to VSV infection than wild-type mice. Mechanistically, TGR5 facilitates type I interferon (IFN-I) production through the AKT/IRF3-signaling pathway, which is crucial in promoting antiviral innate immunity. Taken together, our data reveal a positive feedback loop regulating IRF3 signaling and suggest a potential therapeutic role for metabolite-sensing GPCRs in controlling viral diseases.