Targeting epidermal growth factor receptor signalling pathway: A promising therapeutic option for COVID-19.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is continuously producing new variants, necessitating effective therapeutics. Patients are not only confronted by the immediate symptoms of infection but also by the long-term health issues linked to long COVID-19. Activation of epidermal growth factor receptor (EGFR) signalling during SARS-CoV-2 infection promotes virus propagation, mucus hyperproduction, and pulmonary fibrosis, and suppresses the host's antiviral response. Over the long term, EGFR activation in COVID-19, particularly in COVID-19-induced pulmonary fibrosis, may be linked to the development of lung cancer. In this review, we have summarised the significance of EGFR signalling in the context of SARS-CoV-2 infection. We also discussed the targeting of EGFR signalling as a promising strategy for COVID-19 treatment and highlighted erlotinib as a superior option among EGFR inhibitors. Erlotinib effectively blocks EGFR and AAK1, thereby preventing SARS-CoV-2 replication, reducing mucus hyperproduction, TNF-α expression, and enhancing the host's antiviral response. Nevertheless, to evaluate the antiviral efficacy of erlotinib, relevant clinical trials involving an appropriate patient population should be designed.

Host E3 ligase HUWE1 attenuates the proapoptotic activity of the MERS-CoV accessory protein ORF3 by promoting its ubiquitin-dependent degradation.

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.

UBR5 Acts as an Antiviral Host Factor against MERS-CoV via Promoting Ubiquitination and Degradation of ORF4b.

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. IMPORTANCE ORF4b was an accessory protein unique to MERS-CoV and was not present in SARS-CoV and SARS-CoV-2 which can also cause severe respiratory disease. Moreover, ORF4b inhibited the production of antiviral cytokines in both the cytoplasm and the nucleus, which was likely to be associated with the high lethality of MERS-CoV. However, whether the host proteins regulate the function of ORF4b is unknown. Our study first determined that UBR5, a host E3 ligase, was a potential host anti-MERS-CoV protein that could reduce the protein level of ORF4b and diminish its anti-immunity ability by inducing ubiquitination and degradation. Based on the discovery of ORF4b-UBR5, a critical molecular target, further increasing the degradation of ORF4b caused by UBR5 could provide a new strategy for the clinical development of drugs for MERS-CoV.

An atlas of human viruses provides new insights into diversity and tissue tropism of human viruses.

MOTIVATION: Viruses continue to threaten human health. Yet, the complete viral species carried by humans and their infection characteristics have not been fully revealed. RESULTS: This study curated an atlas of human viruses from public databases and literature, and built the Human Virus Database (HVD). The HVD contains 1131 virus species of 54 viral families which were more than twice the number of the human-infecting virus species reported in previous studies. These viruses were identified in human samples including 68 human tissues, the excreta and body fluid. The viral diversity in humans was age-dependent with a peak in the infant and a valley in the teenager. The tissue tropism of viruses was found to be associated with several factors including the viral group (DNA, RNA or reverse-transcribing viruses), enveloped or not, viral genome length and GC content, viral receptors and the virus-interacting proteins. Finally, the tissue tropism of DNA viruses was predicted using a random-forest algorithm with a middle performance. Overall, the study not only provides a valuable resource for further studies of human viruses but also deepens our understanding toward the diversity and tissue tropism of human viruses. AVAILABILITY AND IMPLEMENTATION: The HVD is available at http://computationalbiology.cn/humanVirusBase/#/. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Hepatocellular Carcinoma Cell-Derived Exosomal miR-21-5p Induces Macrophage M2 Polarization by Targeting RhoB.

M2-like polarized tumor-associated macrophages (TAMs) are the major component of infiltrating immune cells in hepatocellular carcinoma (HCC), which have been proved to exhibit significant immunosuppressive and pro-tumoral effects. However, the underlying mechanism of the tumor microenvironment (TME) educating TAMs to express M2-like phenotypes is still not fully understood. Here, we report that HCC-derived exosomes are involved in intercellular communications and exhibit a greater capacity to mediate TAMs' phenotypic differentiation. In our study, HCC cell-derived exosomes were collected and used to treat THP-1 cells in vitro. Quantitative polymerase chain reaction (qPCR) results showed that the exosomes significantly promoted THP-1 macrophages to differentiate into M2-like macrophages, which have a high production of transforming growth factor-ß (TGF-ß) and interleukin (IL)-10. The analysis of bioinformatics indicated that exosomal miR-21-5p is closely related to TAM differentiation and is associated with unfavorable prognosis in HCC. Overexpressing miR-21-5p in human monocyte-derived leukemia (THP-1) cells induced down-regulation of IL-1ß levels; however, it enhanced production of IL-10 and promoted the malignant growth of HCC cells in vitro. A reporter assay confirmed that miR-21-5p directly targeted Ras homolog family member B (RhoB) 3'-untranslatedregion (UTR) in THP-1 cells. Downregulated RhoB levels in THP-1 cells would weaken mitogen-activated protein kinase (MAPK) axis signaling pathways. Taken together, tumor-derived miR-21-5p promote the malignant advance of HCC, which mediated intercellular crosstalk between tumor cells and macrophages. Targeting M2-like TAMs and intercepting their associated signaling pathways would provide potentially specific and novel therapeutic approaches for HCC treatment.

M6A-mediated upregulation of circMDK promotes tumorigenesis and acts as a nanotherapeutic target in hepatocellular carcinoma.

BACKGROUND: Emerging evidence suggest the critical role of circular RNAs (circRNAs) in disease development especially in various cancers. However, the oncogenic role of circRNAs in hepatocellular carcinoma (HCC) is still largely unknown. METHODS: RNA sequencing was performed to identify significantly upregulated circRNAs in paired HCC tissues and non-tumor tissues. CCK-8 assay, colony formation, transwell, and xenograft mouse models were used to investigate the role of circRNAs in HCC proliferation and metastasis. Small interfering RNA (siRNA) was used to silence gene expression. RNA immunoprecipitation, biotin pull-down, RNA pull-down, luciferase reporter assay and western blot were used to explore the underlying molecular mechanisms. RESULTS: Hsa_circ_0095868, derived from exon 5 of the MDK gene (named circMDK), was identified as a new oncogenic circRNA that was significantly upregulated in HCC. The upregulation of circMDK was associated with the modification of N6-methyladenosine (m6A) and poor survival in HCC patients. Mechanistically, circMDK sponged miR-346 and miR-874-3p to upregulate ATG16L1 (Autophagy Related 16 Like 1), resulting to the activation of PI3K/AKT/mTOR signaling pathway to promote cell proliferation, migration and invasion. Poly (ß-amino esters) (PAEs) were synthesized to assist the delivery of circMDK siRNA (PAE-siRNA), which effectively inhibited tumor progression without obvious adverse effects in four liver tumor models including subcutaneous, metastatic, orthotopic and patient-derived xenograft (PDX) models. CONCLUSIONS: CircMDK could serve as a potential tumor biomarker that promotes the progression of HCC via the miR-346/874-3p-ATG16L1 axis. The PAE-based delivery of siRNA improved the stability and efficiency of siRNA targeting circMDK. The PAE-siRNA nanoparticles effectively inhibited HCC proliferation and metastasis in vivo. Our current findings offer a promising nanotherapeutic strategy for the treatment of HCC.

SARS-CoV-2: Mechanism of infection and emerging technologies for future prospects.

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.

Venous thromboembolic events in patients with COVID-19: a systematic review and meta-analysis.

BACKGROUND: High incidence of venous thromboembolic complications in coronavirus disease 2019 (COVID-19) patients was noted recently. OBJECTIVE: This study aimed to explore the factors associated with prevalence of venous thromboembolism (VTE) in COVID-19 patients. METHODS: A literature search was conducted in several online databases. Fixed effects meta-analysis was performed for the factors associated with prevalence of VTE in COVID-19 patients. RESULTS: A total of 39 studies were analysed in this analysis. The incidence of pulmonary embolism and VTE in severe COVID-19 patients were 17% (95% CI, 13-21%) and 42% (95% CI, 25-60%), respectively. VTE were more common among individuals with COVID-19 of advance age. Male COVID-19 patients are more likely to experience VTE. Higher levels of white blood cell (WBC; WMD = 1.34 × 109/L; 95% CI, 0.84-1.84 × 109/L), D-dimer (WMD = 4.21 µg/ml; 95% CI, 3.77-4.66 µg/ml), activated partial thromboplastin time (APTT; WMD = 2.03 s; 95% CI, 0.83-3.24 s), fibrinogen (WMD = 0.49 µg/ml; 95% CI, 0.18-0.79 g/L) and C-reactive protein (CRP; WMD = 21.89 mg/L; 95% CI, 11.44-32.34 mg/L) were commonly noted in COVID-19 patients with VTE. Patients with lower level of lymphocyte (WMD = -0.15 × 109/L; 95% CI, -0.23--0.07 × 109/L) was at high risk of developing VTE. The incidence of severe condition (OR = 2.66; 95% CI, 1.95-3.62) was more likely to occur among COVID-19 patients who developed VTE. CONCLUSION: VTE is a common complication in severe COVID-19 patients and thromboembolic events are also associated with adverse outcomes.

Cell membrane proteins with high N-glycosylation, high expression and multiple interaction partners are preferred by mammalian viruses as receptors.

MOTIVATION: Receptor mediated entry is the first step for viral infection. However, the question of how viruses select receptors remains unanswered. RESULTS: Here, by manually curating a high-quality database of 268 pairs of mammalian virus-host receptor interaction, which included 128 unique viral species or sub-species and 119 virus receptors, we found the viral receptors are structurally and functionally diverse, yet they had several common features when compared to other cell membrane proteins: more protein domains, higher level of N-glycosylation, higher ratio of self-interaction and more interaction partners, and higher expression in most tissues of the host. This study could deepen our understanding of virus-receptor interaction. AVAILABILITY AND IMPLEMENTATION: The database of mammalian virus-host receptor interaction is available at http://www.computationalbiology.cn: 5000/viralReceptor. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Protein interactome of the deamidase phosphoribosylformylglycinamidine synthetase (PFAS) by LC-MS/MS.

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.

Endoplasmic Reticulum Protein SCAP Inhibits Dengue Virus NS2B3 Protease by Suppressing Its K27-Linked Polyubiquitylation.

Dengue viruses (DENVs) are an emerging threat to global public health. The NS2B3 protease complex of DENV has recently been shown to cleave the antiviral protein STING and thereby subvert the innate immune signaling to facilitate virus replication. Whether host cells have a mechanism to counteract this virus-mediated immunosuppression is unclear. We discovered that the K27-linked polyubiquitination of NS3 protein facilitates its recruitment of NS2B, the formation of NS2B3, and consequently the enhanced cleavage of STING. However, an endoplasmic reticulum (ER) protein, SCAP, through binding to NS2B protein, inhibits the ubiquitination of NS3, rendering NS2B3 protease incapable of binding and cleaving STING. Importantly, ectopic expression of SCAP impaired DENV infection, whereas silencing of SCAP potentiated DENV infection. Collectively, this study uncovered a novel function of SCAP of counteracting the inhibitory action of DENV NS2B3 protease on STING signaling, suggesting that modulation of SCAP levels may have therapeutic implications.IMPORTANCE This study reports the first ubiquitylation target protein in DENV, the NS3 protein, and the unique role of K27-linked polyubiquitylation in NS3's ability to recruit NS2B and formation of the NS2B3 protease complex. Additionally, this study identified novel functions of the ER protein SCAP: one is to compete with NS2B for binding to STING, and the other is to inhibit the ubiquitination of NS3. Both of these functions protect STING from being cleaved by the NS2B3 protease and thus contribute to host antiviral response.

Cathepsin H-Mediated Degradation of HDAC4 for Matrix Metalloproteinase Expression in Hepatic Stellate Cells: Implications of Epigenetic Suppression of Matrix Metalloproteinases in Fibrosis through Stabilization of Class IIa Histone Deacetylases.

In three-dimensional extracellular matrix, mesenchymal cells including hepatic stellate cells (HSCs) gain the ability to express matrix metalloproteinases (MMPs) on injury signals. In contrast, in myofibroblastic HSCs in fibrotic liver, many MMP genes are silenced into an epigenetically nonpermissive state. The mechanism by which the three-dimensional extracellular matrix confers the MMP genes into an epigenetically permissive state has not been well characterized. In continuation of previous work, we show here that the up-regulation of MMP genes is mediated through degradation of class IIa histone deacetylases (HDACs) by certain cysteine cathepsins (Cts). In three-dimensional extracellular matrix culture, CtsH, among other cysteine cathepsins, was up-regulated and localized as puncta in the nuclear and cytoplasmic compartments in a complex with HDAC4 for its degradation. Conversely, along with HSC trans-differentiation, CtsH and CtsL were progressively down-regulated, whereas HDAC4 was concurrently stabilized. The inhibition of cysteine cathepsins by specific proteinase inhibitors or chloroquine, which raises cellular pH, restored HDAC4. Recombinant CtsH could break down HDAC4 in the transfected cells and in vitro at acidic pH. In human cirrhotic liver, activated HSCs express high levels of class IIa HDACs but little CtsH. We propose that cysteine cathepsin-mediated degradation of class IIa HDACs plays a key role in the modulation of MMP expression/suppression and HSC functions in tissue injury and fibrosis.

Recombinant Murine Gamma Herpesvirus 68 Carrying KSHV G Protein-Coupled Receptor Induces Angiogenic Lesions in Mice.

Human gamma herpesviruses, including Kaposi's sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV), are capable of inducing tumors, particularly in in immune-compromised individuals. Due to the stringent host tropism, rodents are resistant to infection by human gamma herpesviruses, creating a significant barrier for the in vivo study of viral genes that contribute to tumorigenesis. The closely-related murine gamma herpesvirus 68 (γHV68) efficiently infects laboratory mouse strains and establishes robust persistent infection without causing apparent disease. Here, we report that a recombinant γHV68 carrying the KSHV G protein-coupled receptor (kGPCR) in place of its murine counterpart induces angiogenic tumors in infected mice. Although viral GPCRs are conserved in all gamma herpesviruses, kGPCR potently activated downstream signaling and induced tumor formation in nude mouse, whereas γHV68 GPCR failed to do so. Recombinant γHV68 carrying kGPCR demonstrated more robust lytic replication ex vivo than wild-type γHV68, although both viruses underwent similar acute and latent infection in vivo. Infection of immunosuppressed mice with γHV68 carrying kGPCR, but not wild-type γHV68, induced tumors in mice that exhibited angiogenic and inflammatory features shared with human Kaposi's sarcoma. Immunohistochemistry staining identified abundant latently-infected cells and a small number of cells supporting lytic replication in tumor tissue. Thus, mouse infection with a recombinant γHV68 carrying kGPCR provides a useful small animal model for tumorigenesis induced by a human gamma herpesvirus gene in the setting of a natural course of infection.

Mcl-1 suppresses abasic site repair following bile acid-induced hepatic cellular DNA damage.

In cholestasis, increases in bile acid levels result in the generation of reactive oxygen species and the induction of DNA damage and mutation. It is believed that bile acid accumulation is associated with liver tumorigenesis. However, the mechanism that underpins this phenomenon remains to be elucidated. Mcl-1, which is overexpressed in hepatic cells, is a pro-survival member of the Bcl-2 family. In this study, we observed that Mcl-1 potently suppresses the repair of bile acid-induced abasic (apurinic/apyrimidinic) sites in DNA lesions. Upon exposure of hepatic cells to glycochenodeoxycholate, one of the major conjugated human bile acids, we observed an increase in AP site accumulation along with induction of poly(ADP-ribose) polymerase and XRCC1 ( X-Ray Repair Cross Complementing 1). In addition, accumulation of Mcl-1 was observed in the nuclei of QGY-7703 cells in response to glycochenodeoxycholate stimulation. Knockdown of endogenous Mcl-1 by RNA interference significantly accelerated the repair of DNA lesions in glycochenodeoxycholate-treated cells. However, unlike XRCC1, poly(ADP-ribose) polymerase was induced following Mcl-1 knockdown. Conversely, poly(ADP-ribose) polymerase suppression was observed following glycochenodeoxycholate treatment of cells overexpressing Mcl-1. Moreover, AP-site counting analyses revealed that DNA repair activity was enhanced in cells overexpressing poly(ADP-ribose) polymerase under glycochenodeoxycholate stress conditions. It is well known that poly(ADP-ribose) polymerase plays a crucial role in the base excision repair pathway. Thus, our findings suggest that Mcl-1 suppresses base excision repair by inhibiting poly(ADP-ribose) polymerase induction following glycochenodeoxycholate-induced DNA damage. These results potentially explain how bile acid accumulation results in genetic instability and carcinogenesis.

IKKϵ negatively regulates RIG-I via direct phosphorylation.

Inhibitor of nuclear factor kappa-B kinase Epsilon (IKKϵ) is an IKK-related kinase. Despite it was originally discovered as a kinase functionally related to TBK-1, studies entailing gene knockout mouse demonstrated that IKKϵ is dispensable for interferon induction by viral infection. In this study, we report that IKKϵ directly phosphorylates a key serine residue within the RNA-binding domain of RIG-I (retinoic acid-inducible gene 1) to inhibit RIG-I-mediate innate immune signaling. Using IKKϵ-deficient MEFs, we found that loss of IKKϵ resulted in increased cytokine production in response to the activation of cytosolic sensors. Biochemical analyses indicated that IKKϵ physically associated with and phosphorylated RIG-I. Mass spectrometry analysis identified that IKKϵ phosphorylated the serine 855 of the RNA-binding pocket of RIG-I carboxyl terminal domain, a residues known to impinge on RNA-binding via phosphorylation. Our findings collectively support the conclusion that IKKϵ modulates innate immune signaling cascades via phosphorylating the RIG-I cytosolic sensor, providing a feedback regulatory mechanism.

Discovery of a Meisoindigo-Derived PROTAC as the ATM Degrader: Revolutionizing Colorectal Cancer Therapy via Synthetic Lethality with ATR Inhibitors.

Meisoindigo (Mei) has long been recognized in chronic myeloid leukemia (CML) treatment. To elucidate its molecular target and mechanisms, we embarked on designing and synthesizing a series of Mei-derived PROTACs. Through this endeavor, VHL-type PROTAC 9b was identified to be highly cytotoxic against SW620, SW480, and K562 cells. Employing DiaPASEF-based quantitative proteomic analysis, in combination with extensive validation assays, we unveiled that 9b potently and selectively degraded ATM across SW620 and SW480 cells in a ubiquitin-proteasome-dependent manner. 9b-induced selective ATM degradation prompted DNA damage response cascades, thereby leading to the cell cycle arrest and cell apoptosis. This pioneering discovery renders the advent of ATM degradation for anti-cancer therapy. Notably, 9b-induced ATM degradation synergistically enhanced the efficacy of ATR inhibitor AZD6738 both in vitro and in vivo. This work establishes the synthetic lethality-inducing properties of ATR inhibitors in the ATM-deficient context, thereby providing new avenues to innovative therapies for colorectal cancer.

Discovery of meisoindigo derivatives as noncovalent and orally available Mpro inhibitors: their therapeutic implications in the treatment of COVID-19.

The progressive emergence of SARS-CoV-2 variants has necessitated the urgent exploration of novel therapeutic strategies to combat the COVID-19 pandemic. The SARS-CoV-2 main protease (Mpro) represents an evolutionarily conserved therapeutic target for drug discovery. This study highlights the discovery of meisoindigo (Mei), derived from the traditional Chinese medicine (TCM) Indigo naturalis, as a novel non-covalent and nonpeptidic Mpro inhibitor. Substantial optimizations and structure-activity relationship (SAR) studies, guided by a structure-based drug design approach, led to the identification of several Mei derivatives, including S5-27 and S5-28, exhibiting low micromolar inhibition against SARS-CoV-2 Mpro with high binding affinity. Notably, S5-28 provided significant protection against wild-type SARS-CoV-2 in HeLa-hACE2 cells, with EC50 up to 2.66 µM. Furthermore, it displayed favorable physiochemical properties and remarkable gastrointestinal and metabolic stability, demonstrating its potential as an orally bioavailable drug for anti-COVID-19 therapy. This research presents a promising avenue for the development of new antiviral agents, offering hope in the ongoing battle against COVID-19.

Exploring extracellular vesicles in zoonotic helminth biology: implications for diagnosis, therapeutic and delivery.

Extracellular vesicles (EVs) have emerged as key intercellular communication and pathogenesis mediators. Parasitic organisms' helminths, cause widespread infections with significant health impacts worldwide. Recent research has shed light on the role of EVs in the lifecycle, immune evasion, and disease progression of these parasitic organisms. These tiny membrane-bound organelles including microvesicles and exosomes, facilitate the transfer of proteins, lipids, mRNAs, and microRNAs between cells. EVs have been isolated from various bodily fluids, offering a potential diagnostic and therapeutic avenue for combating infectious agents. According to recent research, EVs from helminths hold great promise in the diagnosis of parasitic infections due to their specificity, early detection capabilities, accessibility, and the potential for staging and monitoring infections, promote intercellular communication, and are a viable therapeutic tool for the treatment of infectious agents. Exploring host-parasite interactions has identified promising new targets for diagnostic, therapy, and vaccine development against helminths. This literature review delves into EVS's origin, nature, biogenesis, and composition in these parasitic organisms. It also highlights the proteins and miRNAs involved in EV release, providing a comprehensive summary of the latest findings on the significance of EVs in the biology of helminths, promising targets for therapeutic and diagnostic biomarkers.

Lung-Targeted Lipid Nanoparticle-Delivered siUSP33 Attenuates SARS-CoV-2 Replication and Virulence by Promoting Envelope Degradation.

As a structural protein of SARS-CoV-2, the envelope (E) protein not only plays a key role in the formation of viral particles, but also forms ion channels and has pathogenic functions, including triggering cell death and inflammatory responses. The stability of E proteins is controlled by the host ubiquitin-proteasome system. By screening human deubiquitinases, it is found that ubiquitin-specific protease 33 (USP33) can enhance the stability of E proteins depending on its deubiquitinase activity, thereby promoting viral replication. In the absence of USP33, E proteins are rapidly degraded, leading to a reduced viral load and inflammation. Using lipid nanoparticle (LNP) encapsulation of siUSP33 by adjusting the lipid components (ionizable cationic lipids), siUSP33 is successfully delivered to mouse lung tissues, rapidly reducing USP33 expression in the lungs and maintaining knockdown for at least 14 days, effectively suppressing viral replication and virulence. This method of delivery allows efficient targeting of the lungs and a response to acute infections without long-term USP33 deficiency. This research, based on the deubiquitination mechanism of USP33 on the E protein, demonstrates that LNP-mediated siRNA delivery targeting USP33 plays a role in antiviral and anti-inflammatory responses, offering a novel strategy for the prevention and treatment of SARS-CoV-2.