Quantification of the interaction forces between dengue virus and dopamine type-2 receptor using optical tweezers.

BACKGROUND: Dengue virus (DENV) causes the most significant mosquito-borne viral disease with a wide spectrum of clinical manifestation, including neurological symptoms associated with lethal dengue diseases. Dopamine receptors are expressed in central nervous system, and dopamine antagonists have been reported to exhibit antiviral activity against DENV infection in vivo and in vitro. Although identification of host-cell receptor is critical to understand dengue neuropathogenesis and neurotropism, the involvement of dopamine receptors in DENV infection remains unclear. RESULTS: We exploited the sensitivity and precision of force spectroscopy to address whether dopamine type-2 receptors (D2R) directly interact with DENV particles at the first step of infection. Using optical tweezers, we quantified and characterized DENV binding to D2R expressed on Chinese hamster ovary (CHO) cells. Our finding suggested that the binding was D2R- and DENV-dependent, and that the binding force was in the range of 50-60 pN. We showed that dopamine antagonists prochlorperazine (PCZ) and trifluoperazine (TFP), previously reported to inhibit dengue infection, interrupt the DENV-D2R specific binding. CONCLUSIONS: This study demonstrates that D2R could specifically recognize DENV particles and function as an attachment factor on cell surfaces for DENV. We propose D2R as a host receptor for DENV and as a potential therapeutic target for anti-DENV drugs.

Corrigendum: The traditional Chinese medicine formula Jing Guan Fang for preventing SARS-CoV-2 infection: from clinical observation to basic research.

[This corrects the article DOI: 10.3389/fphar.2022.744439.].

Repurposing Astragalus Polysaccharide PG2 for Inhibiting ACE2 and SARS-CoV-2 Spike Syncytial Formation and Anti-Inflammatory Effects.

The outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a serious threat to global public health. In an effort to develop novel anti-coronavirus therapeutics and achieve prophylactics, we used gene set enrichment analysis (GSEA) for drug screening and identified that Astragalus polysaccharide (PG2), a mixture of polysaccharides purified from Astragalus membranaceus, could effectively reverse COVID-19 signature genes. Further biological assays revealed that PG2 could prevent the fusion of BHK21-expressing wild-type (WT) viral spike (S) protein and Calu-3-expressing ACE2. Additionally, it specifically prevents the binding of recombinant viral S of WT, alpha, and beta strains to ACE2 receptor in our non-cell-based system. In addition, PG2 enhances let-7a, miR-146a, and miR-148b expression levels in the lung epithelial cells. These findings speculate that PG2 has the potential to reduce viral replication in lung and cytokine storm via these PG2-induced miRNAs. Furthermore, macrophage activation is one of the primary issues leading to the complicated condition of COVID-19 patients, and our results revealed that PG2 could regulate the activation of macrophages by promoting the polarization of THP-1-derived macrophages into an anti-inflammatory phenotype. In this study, PG2 stimulated M2 macrophage activation and increased the expression levels of anti-inflammatory cytokines IL-10 and IL-1RN. Additionally, PG2 was recently used to treat patients with severe COVID-19 symptoms by reducing the neutrophil-to-lymphocyte ratio (NLR). Therefore, our data suggest that PG2, a repurposed drug, possesses the potential to prevent WT SARS-CoV-2 S-mediated syncytia formation with the host cells; it also inhibits the binding of S proteins of WT, alpha, and beta strains to the recombinant ACE2 and halts severe COVID-19 development by regulating the polarization of macrophages to M2 cells.

Development of Fluorescence-Tagged SARS-CoV-2 Virus-like Particles by a Tri-Cistronic Vector Expression System for Investigating the Cellular Entry of SARS-CoV-2.

Severe acute respiratory syndrome-related coronavirus-2 (SARS-CoV-2) has caused the pandemic that began late December 2019. The co-expression of SARS-CoV-2 structural proteins in cells could assemble into several types of virus-like particles (VLPs) without a viral RNA genome. VLPs containing S proteins with the structural and functional properties of authentic virions are safe materials to exploit for virus-cell entry and vaccine development. In this study, to generate SARS-CoV-2 VLPs (SCoV2-SEM VLPs) composed of three structural proteins including spike (S), envelop (E) protein and membrane (M) protein, a tri-cistronic vector expression system was established in a cell line co-expressing SARS-CoV-2 S, E and M proteins. The SCoV2-SEM VLPs were harvested from the cultured medium, and three structure proteins were confirmed by Western blot assay. A negative-stain TEM assay demonstrated the size of the SCoV2-SEM VLPs with a diameter of about 90 nm. To further characterize the infectious properties of SCoV2-SEM VLPs, the VLPs (atto647N-SCoV2-SEM VLPs) were fluorescence-labeled by conjugation with atto-647N and visualized under confocal microscopy at a single-particle resolution. The results of the infection assay revealed that atto647N-SCoV2-SEM VLPs attached to the surface of the HEK293T cells at the pre-binding phase in a ACE2-dependent manner. At the post-infection phase, atto647N-SCoV2-SEM VLPs either fused with the cellular membrane or internalized into the cytoplasm with mCherry-rab5-positive early endosomes. Moreover, fusion with the cellular membrane and the internalization with early endosomes could be inhibited by the treatment of camostat (a pharmacological inhibitor of TMPRSS2) and chlorpromazine (an endocytosis inhibitor), respectively. These results elucidated that SCoV2-SEM VLPs behave similarly to the authentic live SARS-CoV-2 virus, suggesting that the development of SCoV2-SEM VLPs provide a realistic and safe experimental model for studying the infectious mechanism of SARS-CoV-2.

Effect of heated tobacco products and traditional cigarettes on pulmonary toxicity and SARS-CoV-2-induced lung injury.

Cigarette smoke (CS) significantly contributes to the development of chronic obstructive pulmonary disease (COPD). Heated tobacco products (HTPs), newly developed cigarette products, have been proposed as an alternative for safe cigarette smoking. Although it is plausible to think that replacing traditional cigarettes with HTPs would lower the risks of COPD, this notion requires confirmation by further investigations from sources independent of the tobacco industry. COPD is characterized by an ongoing inflammatory process in the lungs, and the renin-angiotensin system (RAS) has been implicated in the pathogenesis of COPD. Angiotensin-converting enzyme-2 (ACE2) functions as a negative regulator of RAS and has been suggested as a cellular receptor for the causative agent of SARS-CoV-2. It has been shown that smoking is most likely associated with the negative progression and adverse outcomes of SARS-CoV-2. In this study, we found that cigarette smoke extracts from traditional cigarettes (CSE) caused higher cytotoxicity and higher oxidative stress levels than extracts from HTPs (HTPE) in two lung cell lines (Calu-3 and Beas-2B). CSE and HTPE induced RAS activation, MAPK activation, and NF-kB inflammatory pathway activation, resulting in the production of inflammatory cytokines. Furthermore, CSE and a high dose of HTPE reduced tight junction proteins, including claudin 1, E-cadherin, and ZO-1, and disrupted lung epidermal tight junctions at the air-liquid interface (ALI). Finally, CSE and HTPE enhanced the spike protein S1-induced lung injury response. Together, these results suggest that HTPE induced similar lung pathogenesis relevant to COPD and SARS-CoV-2-induced lung injury caused by CSE.

Virofree, an Herbal Medicine-Based Formula, Interrupts the Viral Infection of Delta and Omicron Variants of SARS-CoV-2.

Coronavirus disease 2019 (COVID-19) remains a threat with the emergence of new variants, especially Delta and Omicron, without specific effective therapeutic drugs. The infection causes dysregulation of the immune system with a cytokine storm that eventually leads to fatal acute respiratory distress syndrome (ARDS) and further irreversible pulmonary fibrosis. Therefore, the promising way to inhibit infection is to disrupt the binding and fusion between the viral spike and the host ACE2 receptor. A transcriptome-based drug screening platform has been developed for COVID-19 to explore the possibility and potential of the long-established drugs or herbal medicines to reverse the unique genetic signature of COVID-19. In silico analysis showed that Virofree, an herbal medicine, reversed the genetic signature of COVID-19 and ARDS. Biochemical validations showed that Virofree could disrupt the binding of wild-type and Delta-variant spike proteins to ACE2 and its syncytial formation via cell-based pseudo-typed viral assays, as well as suppress binding between several variant recombinant spikes to ACE2, especially Delta and Omicron. Additionally, Virofree elevated miR-148b-5p levels, inhibited the main protease of SARS-CoV-2 (Mpro), and reduced LPS-induced TNF-α release. Virofree also prevented cellular iron accumulation leading to ferroptosis which occurs in SARS-CoV-2 patients. Furthermore, Virofree was able to reduce pulmonary fibrosis-related protein expression levels in vitro. In conclusion, Virofree was repurposed as a potential herbal medicine to combat COVID-19. This study highlights the inhibitory effect of Virofree on the entry of Delta and Omicron variants of SARS-CoV-2, which have not had any effective treatments during the emergence of the new variants spreading.

Glycosylation and S-palmitoylation regulate SARS-CoV-2 spike protein intracellular trafficking.

Post-translational modifications (PTMs), such as glycosylation and palmitoylation, are critical to protein folding, stability, intracellular trafficking, and function. Understanding regulation of PTMs of SARS-CoV-2 spike (S) protein could help the therapeutic drug design. Herein, the VSV vector was used to produce SARS-CoV-2 S pseudoviruses to examine the roles of the 611LYQD614 and cysteine-rich motifs in S protein maturation and virus infectivity. Our results show that 611LY612 mutation alters S protein intracellular trafficking and reduces cell surface expression level. It also changes S protein glycosylation pattern and decreases pseudovirus infectivity. The S protein contains four cysteine-rich clusters with clusters I and II as the main palmitoylation sites. Mutations of clusters I and II disrupt S protein trafficking from ER-to-Golgi, suppress pseudovirus production, and reduce spike-mediated membrane fusion activity. Taken together, glycosylation and palmitoylation orchestrate the S protein maturation processing and are critical for S protein-mediated membrane fusion and infection.

A Houttuynia cordata-based Chinese herbal formula improved symptoms of allergic rhinitis during the COVID-19 pandemic.

BACKGROUND: The symptoms of coronavirus disease 2019 (COVID-19) such as hyposmia, rhinorrhea, nasal obstruction, and cough are similar to those of chronic allergic rhinitis (AR). Such symptoms can easily lead AR patients to unnecessary anxiety, misdiagnosis, and invasive diagnostic tests in the COVID-19 pandemic. Interleukin-6 (IL-6) is an important mediator for chronic AR and plays a crucial role in the inflammation of COVID-19. Houttuynia cordata (HC) has been shown to reduce nasal congestion and swelling by suppressing the activation of IL-6 and is used to fight COVID-19. A novel HC-based Chinese herbal formula, Zheng-Yi-Fang (ZYF), was developed to test effects on nasal symptoms of patients with AR in the COVID-19 pandemic. METHODS: Participants aged between 20 and 60 years with at least a 2-year history of moderate to severe perennial AR were enrolled. Eligible participants were randomly allocated to either the intervention group (taking ZYF) or the control group (using regular western medicine) for 4 weeks. The Chinese version of the Rhinosinusitis Outcome Measures was used to evaluate impacts on quality of life and nasal symptoms of participants with AR. In addition, the effect of ZYF on lipopolysaccharide (LPS)-induced IL-6 was investigated. RESULTS: Participants with AR taking ZYF improved their symptoms of nasal obstruction, nasal secretion, hyposmia, and postnasal drip in comparison with those of the control group. Meanwhile, ZYF exhibited inhibition of IL-6 secretion in the LPS-induced inflammatory model. CONCLUSION: ZYF has potential effects to relieve nasal symptoms for AR during the COVID-19 pandemic.

The Traditional Chinese Medicine Formula Jing Guan Fang for Preventing SARS-CoV-2 Infection: From Clinical Observation to Basic Research.

COVID-19 is a global epidemic. Developing adjuvant therapies which could prevent the virus from binding to cells may impair viral infection. This study produces a traditional Chinese medicine formula, Jing Guan Fang (JGF), based on ancient medical texts, and examines the efficacy and the mechanism by which JGF prevents viral infections. JGF reduces COVID-19 like symptoms. Functional studies show that JGF inhibits the formation of syncytium and reduces the formation of viral plaque. JGF is not toxic in vitro and in vivo. Mechanistically, JGF induces lysosomal-dependent ACE2 degradation and suppresses mRNA and the protein levels of TMPRSS2 in human lung WI-38 and MRC-5 cells. Mice that inhale JGF exhibit reduced ACE2 and TMPRSS2 protein levels in lung tissues. Together, these findings suggest that JGF may improve the COVID-19 like symptoms and inhibit viral infection. Moreover, JGF may be applicable as an adjuvant preventive strategy against SARS-CoV-2 infection in addition to the use of vaccines.

Honeysuckle (Lonicera japonica) and Huangqi (Astragalus membranaceus) Suppress SARS-CoV-2 Entry and COVID-19 Related Cytokine Storm in Vitro.

COVID-19 is threatening human health worldwide but no effective treatment currently exists for this disease. Current therapeutic strategies focus on the inhibition of viral replication or using anti-inflammatory/immunomodulatory compounds to improve host immunity, but not both. Traditional Chinese medicine (TCM) compounds could be promising candidates due to their safety and minimal toxicity. In this study, we have developed a novel in silico bioinformatics workflow that integrates multiple databases to predict the use of honeysuckle (Lonicera japonica) and Huangqi (Astragalus membranaceus) as potential anti-SARS-CoV-2 agents. Using extracts from honeysuckle and Huangqi, these two herbs upregulated a group of microRNAs including let-7a, miR-148b, and miR-146a, which are critical to reduce the pathogenesis of SARS-CoV-2. Moreover, these herbs suppressed pro-inflammatory cytokines including IL-6 or TNF-α, which were both identified in the cytokine storm of acute respiratory distress syndrome, a major cause of COVID-19 death. Furthermore, both herbs partially inhibited the fusion of SARS-CoV-2 spike protein-transfected BHK-21 cells with the human lung cancer cell line Calu-3 that was expressing ACE2 receptors. These herbs inhibited SARS-CoV-2 Mpro activity, thereby alleviating viral entry as well as replication. In conclusion, our findings demonstrate that honeysuckle and Huangqi have the potential to be used as an inhibitor of SARS-CoV-2 virus entry that warrants further in vivo analysis and functional assessment of miRNAs to confirm their clinical importance. This fast-screening platform can also be applied to other drug discovery studies for other infectious diseases.

Mevalonate Pathway Enzyme HMGCS1 Contributes to Gastric Cancer Progression.

The 3-hydroxy-3-methylglutaryl-CoA synthase 1 (HMGCS1) is a potential regulatory node in the mevalonate pathway that is frequently dysregulated in tumors. This study found that HMGCS1 expression is upregulated in stomach adenocarcinoma samples of patients and tumorspheres of gastric cancer cells. HMGCS1 elevates the expression levels of the pluripotency genes Oct4 and SOX-2 and contributes to tumorsphere formation ability in gastric cancer cells. HMGCS1 also promotes in vitro cell growth and progression and the in vivo tumor growth and lung metastasis of gastric cancer cells. After blocking the mevalonate pathway by statin and dipyridamole, HMGCS1 exerts nonmetabolic functions in enhancing gastric cancer progression. Furthermore, the level and nuclear translocation of HMGCS1 in gastric cancer cells are induced by serum deprivation. HMGCS1 binds to and activates Oct4 and SOX-2 promoters. HMGCS1 also enhances the integrated stress response (ISR) and interacts with the endoplasmic reticulum (ER) stress transducer protein kinase RNA-like endoplasmic reticulum kinase (PERK). Our results reveal that HMGCS1 contributes to gastric cancer progression in both metabolic and nonmetabolic manners.

The Mechanism of the Zika Virus Crossing the Placental Barrier and the Blood-Brain Barrier.

Zika virus (ZIKV) infection causes severe neurological symptoms in adults and fetal microcephaly and the virus is detected in the brain of microcephaly and meningoencephalitis patient. However, the mechanism of ZIKV crossing the physiological barrier to the central nervous systems (CNS) remains elusive. The placental barrier and the blood brain barrier (BBB) protect the fetus from pathogens and ensure healthy brain development during pregnancy. In this study, we used human placenta trophoblasts cells (JEG-3) and human brain-derived endothelial cells (hCMEC/D3) as in vitro models of the physiological barriers. Results showed that ZIKV could infect JEG-3 cells effectively and reduce the amounts of ZO-1 and occludin between adjacent cells by the proteasomal degradation pathway, suggesting that the permeability of the barrier differentially changed in response to ZIKV infection, allowing the virus particle to cross the host barrier. In contrast, ZIKV could infect hCMEC/D3 cells without disrupting the BBB barrier permeability and tight junction protein expression. Although no disruption to the BBB was observed during ZIKV infection, ZIKV particles were released on the basal side of the BBB model and infected underlying cells. In addition, we observed that fluorescence-labeled ZIKV particles could cross the in vitro placenta barrier and BBB model by transcytosis and the action of transcytosis could be blocked by either low temperature or pharmacological inhibitors of endocytosis. In summary, the ZIKV uses a cell-type specific paracellular pathway to cross the placenta monolayer barrier by disrupting cellular tight junction. In addition, the ZIKV can also cross both the placenta barrier and the BBB by transcytosis. Our study provided new insights into on the mechanism of the cellular barrier penetration of ZIKV particles.

Benzenesulfonamide Derivatives as Calcium/Calmodulin-Dependent Protein Kinase Inhibitors and Antiviral Agents against Dengue and Zika Virus Infections.

Emerging and resurging mosquito-borne flaviviruses are an important public health challenge. The increased prevalence of dengue virus (DENV) infection has had a significant socioeconomic impact on epidemic countries. The recent outbreak of Zika virus (ZIKV) has created an international public health emergency because ZIKV infection has been linked to congenital defects and Guillain-Barré syndrome. To develop potentially prophylactic antiviral drugs for combating these acute infectious diseases, we have targeted the host calcium/calmodulin-dependent kinase II (CaMKII) for inhibition. By using CaMKII structure-guided inhibitor design, we generated four families of benzenesulfonamide (BSA) derivatives for SAR analysis. Among these substances, N-(4-cycloheptyl-4-oxobutyl)-4-methoxy-N-phenylbenzenesulfonamide (9) showed superior properties as a lead CaMKII inhibitor and antiviral agent. BSA 9 inhibited CaMKII activity with an IC50 value of 0.79 µM and displayed EC50 values of 1.52 µM and 1.91 µM against DENV and ZIKV infections of human neuronal BE(2)C cells, respectively. Notably, 9 significantly reduced the viremia level and increased animal survival time in mouse-challenge models.

TIM-1 As a Signal Receptor Triggers Dengue Virus-Induced Autophagy.

Dengue virus (DENV) infection triggers the activation of autophagy to facilitate the viral replication cycle from various aspects. Although a number of stimulators are proposed to activate autophagy, none of them appears prior to the uncoating process. Given that T-cell immunoglobulin and mucin domain 1 (TIM-1) receptor is a putative DENV receptor and promotes apoptotic body clearance by autophagy induction, it raises the possibility that TIM-1 may participate in the activation of DENV-induced autophagy. In this study, confocal images first revealed the co-localization of TIM-1 with autophagosomes in DENV-induced autophagy rather than rapamycin-induced autophagy, suggesting the co-transportation of TIM-1 with DENV during infection. The treatment of siRNA to knockdown TIM-1 expression in DENV-infected GFP-microtubule-associated protein light chain 3 (LC3)-Huh7.5 cells revealed that TIM-1 is required not only for DENV cellular internalization but also for autophagy activation. Furthermore, knockdown p85, a subunit of phosphoinositide 3-kinases (PI3Ks), which is co-localized with TIM-1 at rab5-positive endosomes caused the reduction of autophagy, indicating that TIM-1-mediated DENV-induced autophagy requires p85. Taken together, the current study uncovered TIM-1 as a novel factor for triggering autophagy in DENV infection through TIM-1-p85 axis, in addition to serving as a DENV receptor.

MicroRNA-23a/27a/24-2 cluster promotes gastric cancer cell proliferation synergistically.

Previous studies have indicated that certain microRNAs (miRNAs/miRs) function as either tumor suppressors or oncogenes in human cancer. The present study identified the miR-23a/27a/24-2 cluster, containing miR-23, miR-27a and miR-24, as an oncogene in gastric cancer. The expression of the miR-23a/27a/24-2 cluster was upregulated in clinical gastric cancer tissues. Transfection with inhibitors of miR-23a, miR-27a, or miR-24, either independently or together, repressed in vitro colony formation and in vivo tumor formation. The miR23a/27a/24-2 cluster inhibitors repressed the growth of gastric cancer cells in a synergistic manner. In addition, treatment with lower doses of the miRNA inhibitor mixture induced the formation of apoptotic bodies. According to computational predictions using TargetScan, suppressor of cytokine-induced signaling 6 (SOCS6) was identified as one of the downstream target genes of the miR-23a/27a/24-2 cluster. The expression of SOCS6 was significantly lower in tumor tissues than in matched normal tissues (P<0.01) and was associated with poor survival (P<0.00001). Taken together, these results strongly suggested that the miR-23a/27a/24-2 cluster may mediate the progression of gastric cancer through the suppression of SOCS6 expression. The present study also provides a novel molecular target for the development of an anti-gastric cancer agent.

Identification of novel cancer fusion genes using chromosome breakpoint screening.

Gene fusion due to rearrangement or translocation of chromosomes is a powerful mutational mechanism during tumorigenesis. Several new high-resolution technologies have recently been developed to evaluate large numbers of small aberrations as candidate loci for fusion gene screening. In our previous whole-genome screening study using 500K SNP arrays, we identified more than 700 homozygous deletions (HDs) and amplicons in 23 cancer cell lines. To explore novel fusion genes in cancer, we established stringent criteria for defining HD and amplicon breakpoints. Then genomic PCR and sequencing analyses identified a fusion gene, FNDC3B-PRKCI, that resulted from chromosome intra-rearrangement. Western blotting and 3'-RACE analyses revealed that the chimeric transcript was an in-frame fusion between FNDC3B and PRKCI. Finally, cell migration and colony formation assays suggested that FNDC3B-PRKCI is a potential oncogene.

Notch1-promoted TRPA1 expression in erythroleukemic cells suppresses erythroid but enhances megakaryocyte differentiation.

The Notch1 pathway plays important roles in modulating erythroid and megakaryocyte differentiation. To screen the Notch1-related genes that regulate differentiation fate of K562 and HEL cells, the expression of transient receptor potential ankyrin 1 (TRPA1) was induced by Notch1 receptor intracellular domain (N1IC), the activated form of Notch1 receptor. N1IC and v-ets erythroblastosis virus E26 oncogene homolog 1 (Ets-1) bound to TRPA1 promoter region to regulate transcription in K562 cells. Transactivation of TRPA1 promoter by N1IC depended on the methylation status of TRPA1 promoter. N1IC and Ets-1 suppressed the DNA methyltransferase 3B (DNMT3B) level in K562 cells. Inhibition of TRPA1 expression after Notch1 knockdown could be attenuated by nanaomycin A, an inhibitor of DNMT3B, in K562 and HEL cells. Functionally, hemin-induced erythroid differentiation could be suppressed by TRPA1, and the reduction of erythroid differentiation of both cells by N1IC and Ets-1 occurred via TRPA1. However, PMA-induced megakaryocyte differentiation could be enhanced by TRPA1, and the surface markers of megakaryocytes could be elevated by nanaomycin A. Megakaryocyte differentiation could be reduced by Notch1 or Ets-1 knockdown and relieved by TRPA1 overexpression. The results suggest that Notch1 and TRPA1 might be critical modulators that control the fate of erythroid and megakaryocyte differentiation.

Honokiol, a Lignan Biphenol Derived from the Magnolia Tree, Inhibits Dengue Virus Type 2 Infection.

Dengue is the most widespread arbovirus infection and poses a serious health and economic issue in tropical and subtropical countries. Currently no licensed vaccine or compounds can be used to prevent or manage the severity of dengue virus (DENV) infection. Honokiol, a lignan biphenol derived from the Magnolia tree, is commonly used in Eastern medicine. Here we report that honokiol has profound antiviral activity against serotype 2 DENV (DENV-2). In addition to inhibiting the intracellular DENV-2 replicon, honokiol was shown to suppress the replication of DENV-2 in baby hamster kidney (BHK) and human hepatocarcinoma Huh7 cells. At the maximum non-toxic dose of honokiol treatment, the production of infectious DENV particles was reduced >90% in BHK and Huh7 cells. The underlying mechanisms revealed that the expression of DENV-2 nonstructural protein NS1/NS3 and its replicating intermediate, double-strand RNA, was dramatically reduced by honokiol treatment. Honokiol has no effect on the expression of DENV putative receptors, but may interfere with the endocytosis of DENV-2 by abrogating the co-localization of DENV envelope glycoprotein and the early endosomes. These results indicate that honokiol inhibits the replication, viral gene expression, and endocytotic process of DENV-2, making it a promising agent for chemotherapy of DENV infection.

The reciprocal regulation loop of Notch2 pathway and miR-23b in controlling gastric carcinogenesis.

Gastric carcinoma is one of the most common malignancies and the third highest cause of global cancer-related death. Notch2 receptor intracellular domain (N2IC), the activated form of Notch2 receptor, enhances gastric carcinogenesis. MicroRNAs (miRNAs) act as either oncogenes or tumor suppressors in tumorigenesis and cross-talk with Notch pathways. Herein, microRNA-23b (miR-23b) was identified as a Notch2 receptor-related miRNA and its role in gastric carcinogenesis was investigated. Levels of miR-23b in stomach adenocarcinoma samples were down-regulated, whereas those of Notch2 receptor, v-ets erythroblastosis virus E26 oncogene homolog 1 (Ets1), and E2F1 transcripts were up-regulated. Results also showed that N2IC down-regulated miR-23b expression in gastric cancer cells through up-regulating E2F1. The miR-23b inhibited gastric tumorigenesis including growth, viability, epithelial-mesenchymal transition, and abilities of colony formation, migration, invasion, and tumorsphere formation. Mechanistically, miR-23b suppressed tumor progression and pluripotency gene expression and affected tumorsphere ultra-structure in gastric cancer cells via targeting Notch2 receptor or Ets1. Furthermore, miR-23b diminished the xenografted tumor growth and lung metastasis of SC-M1 gastric cancer cells through Notch2 pathway. Our results suggest that Notch2 pathway and miR-23b interplay in a reciprocal regulation loop in gastric cancer cells and this axis plays an important role in gastric carcinogenesis.

Intracellular Transport of Vaccinia Virus in HeLa Cells Requires WASH-VPEF/FAM21-Retromer Complexes and Recycling Molecules Rab11 and Rab22.

UNLABELLED: Vaccinia virus, the prototype of the Orthopoxvirus genus in the family Poxviridae, infects a wide range of cell lines and animals. Vaccinia mature virus particles of the WR strain reportedly enter HeLa cells through fluid-phase endocytosis. However, the intracellular trafficking process of the vaccinia mature virus between cellular uptake and membrane fusion remains unknown. We used live imaging of single virus particles with a combination of various cellular vesicle markers, to track fluorescent vaccinia mature virus particle movement in cells. Furthermore, we performed functional interference assays to perturb distinct vesicle trafficking processes in order to delineate the specific route undertaken by vaccinia mature virus prior to membrane fusion and virus core uncoating in cells. Our results showed that vaccinia virus traffics to early endosomes, where recycling endosome markers Rab11 and Rab22 are recruited to participate in subsequent virus trafficking prior to virus core uncoating in the cytoplasm. Furthermore, we identified WASH-VPEF/FAM21-retromer complexes that mediate endosome fission and sorting of virus-containing vesicles prior to virus core uncoating in the cytoplasm. IMPORTANCE: Vaccinia mature virions of the WR strain enter HeLa cells through fluid phase endocytosis. We previously demonstrated that virus-containing vesicles are internalized into phosphatidylinositol 3-phosphate positive macropinosomes, which are then fused with Rab5-positive early endosomes. However, the subsequent process of sorting the virion-containing vesicles prior to membrane fusion remains unclear. We dissected the intracellular trafficking pathway of vaccinia mature virions in cells up to virus core uncoating in cytoplasm. We show that vaccinia mature virions first travel to early endosomes. Subsequent trafficking events require the important endosome-tethered protein VPEF/FAM21, which recruits WASH and retromer protein complexes to the endosome. There, the complex executes endosomal membrane fission and cargo sorting to the Rab11-positive and Rab22-positive recycling pathway, resulting in membrane fusion and virus core uncoating in the cytoplasm.