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Within the past 2 decades, three highly pathogenic human coronaviruses have emerged, namely, severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The health threats and economic burden posed by these tremendously severe coronaviruses have paved the way for research on their etiology, pathogenesis, and treatment. Compared to SARS-CoV and SARS-CoV-2, MERS-CoV genome encoded fewer accessory proteins, among which the ORF4b protein had anti-immunity ability in both the cytoplasm and nucleus. Our work for the first time revealed that ORF4b protein was unstable in the host cells and could be degraded by the ubiquitin proteasome system. After extensive screenings, it was found that UBR5 (ubiquitin protein ligase E3 component N-recognin 5), a member of the HECT E3 ubiquitin ligases, specifically regulated the ubiquitination and degradation of ORF4b. Similar to ORF4b, UBR5 can also translocate into the nucleus through its nuclear localization signal, enabling it to regulate ORF4b stability in both the cytoplasm and nucleus. Through further experiments, lysine 36 was identified as the ubiquitination site on the ORF4b protein, and this residue was highly conserved in various MERS-CoV strains isolated from different regions. When UBR5 was knocked down, the ability of ORF4b to suppress innate immunity was enhanced and MERS-CoV replication was stronger. As an anti-MERS-CoV host protein, UBR5 targets and degrades ORF4b protein through the ubiquitin proteasome system, thereby attenuating the anti-immunity ability of ORF4b and ultimately inhibiting MERS-CoV immune escape, which is a novel antagonistic mechanism of the host against MERS-CoV infection.

The Wnt/β-catenin signaling pathway has been implicated as the central mechanism that drives colorectal carcinogenesis. Its activation is historically due to mutation on APC (adenomatous polyposis coli), resulting to nuclear localization of β-catenin and expression of Wnt target genes that promote tumor progression. Although this pathway seems to be a pivotal therapeutic target because of its critical role in colorectal cancer, there has been no clinically approved therapies targeting Wnt/β-catenin signaling pathway to this date. Here, we reviewed the recent progress of this signal transduction pathway in colorectal tumorigenesis. Apart from their roles in cancer initiation, the new pathway modulators (activators and repressors) also participate in chemoresistance, epithelial-mesenchymal transition and cancer stem cell renewal. Of the proteins reported to modulate this pathway, CDX2 (Caudal-related homeobox transcription factor 2) showed potentials as promising molecular target. CDX2 warrants further studies to determine its significance as molecular target for colorectal cancer therapeutics. Overall, the regulation of Wnt/β-catenin signaling pathway remains intriguingly complex and is not fully understood in spite of the widespread research efforts. Its intricacy remains a major barrier in the development of chemotherapeutic agent that specifically targets it.

Background Autophagy is a self-degrading process. Previously, we showed that insulin-like growth factor binding protein-related protein 1 (IGFBPrP1) is a novel transforming growth factor β1 (TGFβ1)-interacting factor in liver fibrosis; the role of TGFβ1-mediated autophagy in hepatic stellate cells (HSCs) activation has been investigated. However, whether autophagy is regulated by IGFBPrP1 remains unknown. Aims We investigated the interactions among IGFBPrP1, autophagy, and activation of primary rat HSCs. Methods Primary HSCs were separated from Sprague Dawley rats by two-step enzymatic digestion, and then, we overexpressed or inhibited IGFBPrP1 expression in HSCs under serum-starved condition. Autophagy inducer rapamycin or inhibitor 3-methyladenine (3MA) was used to assess the relationship between autophagy and HSCs activation. Results We observed the expression of activation marker α-SMA and autophagy markers such as LC3B and Beclin1, which were significantly increased in HSCs treated with adenovirus vector harboring the IGFBPrP1 gene (AdIGFBPrP1) compared to cells cultured under serum-starved. In comparison, HSCs treated with shIGFBPrP1 showed opposite results. Furthermore, HSCs activation and autophagy increased when cells were treated with rapamycin, whereas opposite results were obtained when cells were treated with 3MA. AdIGFBPrP1 treatment downregulated the phosphorylation of Akt and mTOR. Conclusion Autophagy was induced in IGFBPrP1-treated primary HSCs, and IGFBPrP1-induced autophagy promoted the activation of HSCs and extracellular matrix expression, the underlying mechanism of which may involve the phosphatidylinositide 3-kinase/Akt/mTOR signaling pathway.

Phosphoribosylformylglycinamidine synthase (PFAS) is an essential enzyme in de novo synthesis of purine. Previously, PFAS has been reported to modulate RIG-I activation during viral infection via deamidation. In this study, we sought to identify potential substrates that PFAS can deamidate. Flag-PFAS was transfected into HEK-293T cells and PFAS associated proteins were purified with anti-Flag M2 magnetic beads. PFAS associated proteins were identified using mass spectrometry and were analyzed using bioinformatics tools including KEGG pathway analysis, gene ontology annotation, and protein interaction network analysis. A total of 441 proteins is suggested to potentially interact with PFAS. Of this number, 12 were previously identified and 429 are newly identified. The interactions of PFAS with CAD, CCT2, PRDX1, and PHGDH were confirmed by co-immunoprecipitation and western blotting. This study is first to report the interaction of PFAS with several proteins which play physiological roles in tumor development including CAD, CCT2, PRDX1, and PHGDH. Furthermore, we show here that PFAS is able to deamidate PHGDH, and induce other posttranslational modification into CAD, CCT2 and PRDX1. The present data provide insight on the biological function of PFAS. Further study to explore the role of these protein interactions in tumorigenesis and other diseases is recommended.

Background: Post-stroke depression(PSD) lacks timely and effective treatment and virtual reality (VR) technology can create a lifelike experience and simulate users' physical presence in an immersive environment. It has been confirmed to have a positive effect on stroke and depression. Data about the efficacy VR on PSD are limited. The intensification of fibroblast growth factor 21(FGF21) can improve depression and other emotional symptoms, but there is no study on its role in PSD.Methods: We enlisted 76 PSD patients (6 lost) and divided into the experimental group and control group randomly. The patient underwent psychological rehabilitation once a week for 50 minutes each time for a total of 12 weeks. The patients in the experimental group received psychological counseling and VR rehabilitation while patients in the control group also took the same pattern but without VR rehabilitation. The Hamilton Depression Scale (HAMD) and Hamilton Anxiety Scale (HAMA) were evaluated before rehabilitation, in the 4th week and at the end of rehabilitation respectively in two groups for the sake of observing changes in the patients' depression. Then 8 people in each group did functional near-infrared spectroscopy (fNIRS), and blood samples were taken for detection with brain-derived neurotrophic factor (BDNF), IL-6, TNF-α and FGF21 by ELISA.Results: The result of fNIRS showed the hemodynamic activation in the prefrontal region of the experimental group was significantly increased. Both groups of FGF21 increased and compared with the control group, the experimental group has a greater upsurge and a faster increase rate.Conclusions: VR alleviates PSD. FGF21 is closely related to PSD，and it is likely to be a potential pathological mechanism of PSD. It suggests that VR is possible to improve PSD by increasing FGF21.Trial registration: We registered in Chinese Clinical Trial Registry which is the first level registration organization of WHO international clinical trial registration platform. The registration number is ChiCTR1900027987, the date of registration December 7, 2019.

SARS-CoV-2 is the etiological agent responsible for the ongoing pandemic of coronavirus disease 2019 (COVID-19). The main protease of SARS-CoV-2, 3CLpro, is an attractive target for antiviral inhibitors due to its indispensable role in viral replication and gene expression of viral proteins. The search of compounds that can effectively inhibit the crucial activity of 3CLpro, which results to interference of the virus life cycle, is now widely pursued. Here, we report that epigallocatechin-3-gallate (EGCG), an active ingredient of Chinese herbal medicine (CHM), is a potent inhibitor of 3CLpro with half-maximum inhibitory concentration (IC50) of 0.874 ± 0.005 μM. In the study, we retrospectively analyzed the clinical data of 123 cases of COVID-19 patients, and found three effective Traditional Chinese Medicines (TCM) prescriptions. Multiple strategies were performed to screen potent inhibitors of SARS-CoV-2 3CLpro from the active ingredients of TCMs, including network pharmacology, molecular docking, surface plasmon resonance (SPR) binding assay and fluorescence resonance energy transfer (FRET)-based inhibition assay. The SPR assay showed good interaction between EGCG and 3CLpro with KD ~6.17 μM, suggesting a relatively high affinity of EGCG with SARS-CoV-2 3CLpro. Our results provide critical insights into the mechanism of action of EGCG as a potential therapeutic agent against COVID-19.

The novel coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread globally to over 200 countries with more than 23 million confirmed cases and at least 800,000 fatalities as of 23 August 2020. Declared a pandemic on March 11 by World Health Organization, the disease caused by SARS-CoV-2 infection, called coronavirus disease 2019 (COVID-19), has become a global public health crisis that challenged all national healthcare systems. This review summarized the current knowledge about virologic and pathogenic characteristics of SARS-CoV-2 with emphasis on potential immunomodulatory mechanism and drug development. With multiple emerging technologies and cross-disciplinary approaches proving to be crucial in our global response against COVID-19, the application of PROteolysis TArgeting Chimeras strategy, CRISPR-Cas9 gene editing technology, and Single-Nucleotide-Specific Programmable Riboregulators technology in developing antiviral drugs and detecting infectious diseases are proposed here. We also discussed the available but still limited epidemiology of COVID-19 as well as the ongoing efforts on vaccine development. In brief, we conducted an in-depth analysis of the pathogenesis of SARS-CoV-2 and reviewed the therapeutic options for COVID-19. We also proposed key research directions in the future that may help uncover more underlying molecular mechanisms governing the pathology of COVID-19.

With the outbreak of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), coronaviruses have begun to attract great attention across the world. Of the known human coronaviruses, however, Middle East respiratory syndrome coronavirus (MERS-CoV) is the most lethal. Coronavirus proteins can be divided into three groups: nonstructural proteins, structural proteins, and accessory proteins. While the number of each of these proteins varies greatly among different coronaviruses, accessory proteins are most closely related to the pathogenicity of the virus. We found for the first time that the ORF3 accessory protein of MERS-CoV, which closely resembles the ORF3a proteins of severe acute respiratory syndrome coronavirus and SARS-CoV-2, has the ability to induce apoptosis in cells in a dose-dependent manner. Through bioinformatics analysis and validation, we revealed that ORF3 is an unstable protein and has a shorter half-life in cells compared to that of severe acute respiratory syndrome coronavirus and SARS-CoV-2 ORF3a proteins. After screening, we identified a host E3 ligase, HUWE1, that specifically induces MERS-CoV ORF3 protein ubiquitination and degradation through the ubiquitin-proteasome system. This results in the diminished ability of ORF3 to induce apoptosis, which might partially explain the lower spread of MERS-CoV compared to other coronaviruses. In summary, this study reveals a pathological function of MERS-CoV ORF3 protein and identifies a potential host antiviral protein, HUWE1, with an ability to antagonize MERS-CoV pathogenesis by inducing ORF3 degradation, thus enriching our knowledge of the pathogenesis of MERS-CoV and suggesting new targets and strategies for clinical development of drugs for MERS-CoV treatment.

Objective β-catenin is one of the most critical oncogenes associated with many kinds of human cancers, especially in the human CRC. Innate immunity recognizes tumour derived damage-associated molecular patterns (DAMPs) and primes the anti-tumour adaptive responses. While the function of β-catenin in CRC tumourigenesis is well established, its impact on innate immune evasion is largely unknown. The aim of this study is to characterize the role of β-catenin in inhibiting RIG-I-like receptor (RLR)-mediated IFN-β signalling in colorectal cancer. Materials and methods Immunohistochemical staining and western blotting were conducted to study the expression of β-catenin, IRF3 and phospho-IRF3 (p-IRF3) in CRC samples and cell lines. Plaque assay determining virus replication was performed to assess the regulation of β-catenin on IFN-β signalling. The inhibition of β-catenin on RLR-mediated IFN-β signalling was further studied by real-time analyses and reporter assays in the context of lentiviral-mediated β-catenin stably knocking down. Lastly, co-immunoprecipitation and nuclear fractionation assay were conducted to monitor the interaction between β-catenin and IRF3. Results We found that high expression of β-catenin positively correlated with the expression of IRF3 in CRC cells. Overexpression of β-catenin increased the viral replication. Conversely knocking down of β-catenin inhibited viral replication. Furthermore, our data demonstrated that β-catenin could inhibit the expression of IFN-β and interferon-stimulated gene 56 (ISG56). Mechanistically, we found that β-catenin interacted with IRF3 and blocked its nuclear translocation. Conclusion Our study reveals an unprecedented role of β-catenin in enabling innate immune evasion in CRC.

Objective Aberrant activation of Wnt/β-catenin signalling contributes significantly to the development of human colorectal cancers and β-catenin is the key signalling molecule transducing canonical Wnt/β-catenin signalling. Therefore, β-catenin is a promising therapeutic target for cancer treatment. This study demonstrates that the oncogenic IKKe kinase phosphorylates β-catenin to restrain its hyper activation, therefore promoting colorectal cancer (CRC) cell proliferation. Materials and methods IKKe and β-catenin expression levels in human colorectal cancer tissues and cell lines were analysed by immunohistochemical staining and Western blotting. The regulation of IKKe on Wnt/β-catenin signalling pathway was studied by reporter assay and real-time PCR analysis in the context of IKKe stably knocking down. Co-immunoprecipitation was conducted to monitor the interaction between IKKe and β-catenin. Kinase assay was performed to measure β-catenin post-translational modifications induced by IKKe. Results Oncogenic IKKe kinase is required for the proliferation of colorectal cancer cells. Mechanistically, inhibition of IKKe results in β-catenin hyper activation and thwarts CRC cell proliferation. Furthermore, IKKe phosphorylates β-catenin and inhibits the activation of β-catenin signalling. Conclusion Our study suggests that IKKe is a potential target to combat CRC induced by aberrant Wnt/β-catenin signalling.

Summary What is known and objective Silibinin (Silybin), a major constituent of the milk thistle, is commonly used to treat chronic liver disease in some countries. It has been reported to inhibit the transport activity of ABCB1. This study was carried out to determine whether ABCB1 C3435T polymorphism influenced the pharmacokinetics of silibinin contained in silymarin capsules. Methods Twenty-three healthy volunteers (10 ABCB1 CC, 8 CT and 5 TT genotypes) were enrolled in this clinical trial. Each volunteer was given a single dose of 140 mg Silymarin Capsule. Blood samples were then collected up to 12 h. HPLC-MS/MS was used to detect serial blood concentration of silybin. Results and discussion The peak plasma concentration (Cmax) in subjects of CC (144·8 ± 60·1 ng/mL) and CT (129·3 ± 50·3 ng/mL) genotypes were 2-fold higher than in subjects of TT genotype (60·1 ± 18·3 ng/mL) (with P = 0·0007 and P = 0·0115 respectively). The area under the concentration–time curve (AUC) extrapolated to infinity [AUC(0-∞)] of CC carriers (347·1 ± 133·8 ng/mL h) was significantly higher than that of TT carriers (228·3 ± 52·9 ng/mL h) (P = 0·0115). What is new and conclusion The pharmacokinetics of silibinin was significantly influenced by ABCB1 C3435T polymorphism. Dosage adjustment may be necessary for subjects of different genotypes to ensure comparative exposures. A dose-ranging clinical trial should be undertaken to determine whether the observed differences are clinically significant.