Base-Mediated α-gem-Difluoroalkenylations of Aldehydes and Ketones.

Herein, we present a base-mediated nucleophilic substitution reaction of α-trifluoromethylstyrenes with simple silyl enol ethers, enabling the efficient synthesis of carbonyl-substituted gem-difluoroalkenes. The merit of this protocol is exhibited by its mild reaction conditions, broad substrate scope, and scalable preparation. Notably, this method demonstrates its applicability for late-stage functionalization of structurally complex molecules. Moreover, we illustrate that the resulting products can serve as valuable precursors for the synthesis of diverse medicinally relevant compounds.

LncRNA ATB promotes the proliferation and metastasis of lung cancer via activation of the p38 signaling pathway.

Long non-coding RNA (lncRNA) activated by TGF-ß (ATB) has been reported to be widely expressed in different types of cancer; however, the function of ATB in lung cancer remains unclear. In order to elucidate the role of ATB in lung cancer, reverse transcription-quantitative polymerase chain reaction was used to detect the expression of ATB in tumor tissues and corresponding non-tumor lung tissues from 32 patients with lung cancer. Furthermore, the association between the expression of ATB and clinical characteristics was investigated. Cell proliferation was assessed using a cell counting kit-8 assay and cell migration was assessed using a wound healing assays. Epithelial-mesenchymal-transition and mitogen-activated protein kinase signaling pathway activity was examined using western blotting. It was demonstrated that ATB was highly expressed in lung cancer tissues compared with noncancerous tissues, and associated with tumor size and metastasis. It was also demonstrated that ATB was highly expressed in the lung cancer cell lines, A549 and HCC827, compared with the HBE-1 cell line. Suppression of ATB significantly inhibited the proliferation and migratory rate of lung cancer cells. The protein expression levels of p38, E-cadherin and N-cadherin were altered by suppression of ATB expression. Overall, the present study demonstrated that ATB may promote the development of lung cancer.

MiR-1246 Promotes LPS-Induced Inflammatory Injury in Chondrogenic Cells ATDC5 by Targeting HNF4γ.

BACKGROUND/AIMS: Osteoarthritis (OA) is a common inflammatory joint disease. miRNAs are associated with OA and functionally implicated in the pathogenesis of the disease. In the present study, we investigated the role of miR-1246 in the lipopolysaccharide (LPS)-induced inflammatory injury of ATDC5 cells. METHODS: ATDC5 cells were cultured and treated with LPS in a series of concentration (0, 1, 5, and 10 µg/ml) for 5 h. The cells were transfected with miR-1246-mimic, inhibitor, si-HNF4γ or negative control, then were assessed for cell viability using CCK8 assay, apoptosis by flow-cytometry and expressions of miR-1246 and pro-inflammatory cytokines by qRT-PCR and western blot analysis. RESULTS: Cell viability was significantly reduced and cell apoptosis was added in ATDC5 cells injured with LPS at the dosage of 5 and 10 µg/ml. Relative mRNA expressions of pro-inflammatory cytokines (IL-1ß, IL-6, IL-8 and TNF-α) were significantly increased. miR-1246 was up-regulated in ATDC5 cells treated with LPS. Moreover, miR-1246 overexpression aggravated LPS-induced decrease in cell viability, increase in apoptosis and overproduction of pro-inflammatory factors. mRNA and protein expressions of HNF4γ were significantly suppressed in cells transfected with miR-124-mimic. Further, miR-1246 knockdown alleviated LPS-induced inflammatory injury by up-regulating the expression of HNF4γ and activation of PI3K/AKT and JAK/STAT pathways. CONCLUSIONS: Suppression of miR-1246 alleviated LPS-induced inflammatory injury in chondrogenic ADTC5 cells by up-regulation of HNF4γ and activation of PI3K/AKT and JAK/STAT pathways. The findings of this study will provide a novel viewpoint regarding miR-1246 target for clinical.

ROCK is involved in vimentin phosphorylation and rearrangement induced by dengue virus.

Our previous study showed that dengue virus 2 (DENV2) infection induces rearrangement of vimentin into dense structures at the perinuclear area. However, the underlying mechanism of this phenomenon is poorly characterized. In the present work, we found that vimentin and Ser71 phosphorylated vimentin display similar distributions in DENV2-infected cells. DENV2 infection also induced ROCK activation and phosphorylation of vimentin at Ser71 as the DENV2 infection progressed. Furthermore, Ser71 phosphorylation and vimentin rearrangement induced by DENV2 infection were blocked by the ROCK inhibitor Y-27632. In addition, DENV2 led to endoplasmic reticulum (ER) redistribution in the perinuclear region of the host cells, which was partially blocked by pretreatment with Y-27632. Together, these data support indicate that ROCK may have a role in governing regulating vimentin and ER rearrangement during DENV2 infection. We hypothesize that DENV2 infection, via ROCK activation, induces both vimentin rearrangement and ER redistribution around the perinuclear region, which may play a structural role in anchoring DENV2 to replication sites.

Roles of small GTPase Rac1 in the regulation of actin cytoskeleton during dengue virus infection.

BACKGROUND: Increased vascular permeability is a hallmark feature in severe dengue virus (DV) infection, and dysfunction of endothelial cells has been speculated to contribute in the pathogenesis of dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). Rho-family GTPase Rac1 is a significant element of endothelial barrier function regulation and has been implicated in the regulation of actin remodeling and intercellular junction formation. Yet there is little evidence linking Rac1 GTPase to alteration in endothelial cell function induced by DV infection. METHODS AND FINDINGS: Here, we showed that actin is essential for DV serotype 2 (DV2) entry into and release from ECV304 cells, and Rac1 signaling is involved these processes. At early infection, actin cytoskeleton rearranged significantly during 1 hour post infection, and disrupting actin filament dynamics with jasplakinolide or cytochalasin D reduced DV2 entry. DV2 entry induced reduction of Rac1 activity within 1 hour post infection. The expression of dominant-negative forms of Rac1 established that DV2 entry is negatively regulated by Rac1. At late infection, actin drugs also inhibited the DV2 release and induced accumulation of viral proteins in the cytoplasm. Meanwhile, the activity of Rac1 increased significantly with the progression of DV2 infection and was up-regulated in transfected cells expressing E protein. Confocal microscopy showed that DV2 E protein was closely associated with either actin or Rac1 in DV2-infected cells. The interaction between E protein and actin was further confirmed by co-immunoprecipitation assay. CONCLUSIONS: These results defined roles for actin integrity in DV2 entry and release, and indicated evidence for the participation of Rac1 signaling pathways in DV2-induced actin reorganizations and E-actin interaction. Our results may provide further insight into the pathogenesis of DHF/DSS.

Co-expression of Japanese encephalitis virus prM-E-NS1 antigen with granulocyte-macrophage colony-stimulating factor enhances humoral and anti-virus immunity after DNA vaccination.

Japanese encephalitis virus (JEV) is an agent of Japanese encephalitis, and granulocyte-macrophage colony-stimulating factor (GM-CSF) is an attractive DNA vaccine adjuvant for its antigen presentation. In the present study, we have constructed DNA vaccines that carried JEV prM-E-NS1 genes with or without the GM-CSF gene. Immunization with the bicistronic plasmid pCAG-JEGM that co-expresses GM-CSF and viral prM-E-NS1, resulted in the highest IgG response and sufficient protection against virus-challenged BALB/c mice. However, much to our surprise, co-inoculation of the GM-CSF plasmid with the pCAG-JE plasmid expressing viral prM-E-NS1 lead to a low antibody titer and a relatively low survival rate. Moreover, anamnestic antibody-mediated protection played a dominant role in the mice JEV challenge model, according to the enhancement of post-challenge neutralizing antibody titers and further adoptive transfer experiments. Taken together, this study should encourage further development of JEV DNA vaccine strategies and caution against the use of cytokines as an adjuvant.

Myosin Vc, a member of the actin motor family associated with Rab8, is involved in the release of DV2 from HepG2 cells.

OBJECTIVE: The pathogenesis of the dengue virus (DV) infection has not been well defined. We have reported that actin and Rab8 are involved in DV2 infection. Myosin Vc (Myo5c) is a novel member of the class V myosins and regulates the actin-mediated membrane trafficking associated with Rab8. In this study, the involvement of Myo5c in the release of DV2 was investigated in HpeG2 cells. METHODS: Distributions of actin, Myo5c, DV2 and Rab8 were revealed by fluorescent staining. HepG2(Myo5c-tail) cells expressing a dominant-negative mutant of Myo5c were constructed by transfection and were assessed by Western blotting. The viral titers were detected by plaque assay, and the expression of Rab8 was analyzed by flow cytometry. RESULTS: DV2 infection altered the distribution pattern of Myo5c, which might be associated with the depolymerization of actin, though colocalization rates of Myo5c with DV2 or actin were low. Furthermore, the release of DV2, but not the intracellular viral production, was reduced from HepG2(Myo5c-tail) cells. Moreover, Myo5c colocalized with Rab8 and an increase of Rab8 was associated with the decrease of the viral release caused by the Myo5c tail. CONCLUSIONS: Our data suggest that Myo5c associated with Rab8 is involved in the release of DV2 from HepG2 cells.

Entry of dengue virus serotype 2 into ECV304 cells depends on clathrin-dependent endocytosis, but not on caveolae-dependent endocytosis.

Caveolae- and clathrin-mediated endocytosis are major internalization pathways used by several pathogens; however, their distinctive roles in dengue virus (DV) entry have not been addressed. In this study, we compared the involvement of caveolae- and clathrin-mediated endocytosis in the infectious entry of DV serotype 2 (DV2) into human endothelial-like ECV304 cells. Confocal microscopy study on DV2-infected cells showed that viral antigens were co-localized with clathrin heavy chains, epidermal growth factor pathway substrate clone 15 (Eps15), and adaptin-alpha, but not with caveolin-1. Treatment with chlorpromazine, which inhibits clathrin-dependent endocytosis, led to reduced virus entry into cells, whereas treatment with nystatin, a caveolae inhibitory agent, did not. Furthermore, gene silencing of Eps15 resulted in an average of 75% reduced infection of ECV304 cells by DV2. Our results demonstrated that DV2 enters ECV304 cells by clathrin-dependent endocytosis, not by caveolae-dependent endocytosis.

Passive protection assay of monoclonal antibodies against dengue virus in suckling mice.

Dengue fever and dengue hemorrhagic fever/dengue shock syndrome are highly infectious diseases caused by dengue virus (DV). Specific monoclonal antibodies (mAbs) against DV are vital for diagnosis, pathological studies, and passive immune therapy. In this study, purified DV serotype 2 (DV2) was used as antigen and BALB/c mice were immunized to induce specific antibodies. We established five hybridoma cell lines, called 78#, 1E7, 7F7, 8F12, and 8H1, respectively, and evaluated them by enzyme-linked immunosorbent assay, indirect immunofluorescence assay, Western blot, plaque reduction neutralization test, and suckling mice protection assay. Lines 78#, 1E7, 7F7, and 8F12 showed a neutralizing effect, and lines 78#, 1E7, 8F12, and 8H1 recognized envelope glycoprotein of DV2. Among them, lines 78# and 8F12 had stronger neutralizing ability in vitro and could protect some suckling mice from virus challenge. Our results demonstrate that immunization with purified virion is efficient for the production of specific neutralizing mAbs against DV2, and these mAbs could be useful tools for studying or treating DV infection.

(Z)-4-[4-(Dimethyl-amino)benzyl-idene]-3-methyl-isoxazol-5(4H)-one.

The title compound, C(13)H(14)N(2)O(2), an isoxazol-5-one derivative, was synthesized by a one-pot, three-component condensation reaction of methyl acetoacetate, hydroxy-lamine hydro-chloride and 4-(dimethyl-amino)benzaldehyde. All the non-H atoms are co-planar [r.m.s deviation = 0.0039 Å], with a Z configuration about the C=C bond. The dihedral angle between the phenyl ring and the isoxazole ring is 2.58 (19)°.

Rab8, a vesicular traffic regulator, is involved in dengue virus infection in HepG2 cells.

OBJECTIVE: The pathogenesis of dengue virus (DV) has not been completely clarified. Rab8 regulates vesicular traffic from Golgi to plasma membrane where DV is matured and then delivered by exocytosis. In this study, involvement of Rab8 in DV serotype 2 (DV2) infection was investigated in HpeG2 cells. METHODS: Distributions of Rab8 and DV2, and the number of infection cells were observed by immunostaining. HepG2(Rab8AM) and HepG2(Rab8DN) cells were constructed to stably express a constitutively active mutant of Rab8 and a dominant negative mutant, respectively, which were assessed by flow cytometry. Production of infectious virions and the amounts of DV2 entry were detected by standard plaque assay. Viral RNA replication was detected by real-time RT-PCR. RESULTS: Rab8 showed high co-localization with DV2 in HpeG2 cells and the amount of DV antigen-positive cells decreased in HepG2(Rab8AM) and HepG2(Rab8DN) cells. Also, progeny virus released from those cells was drastically reduced. Infectious virions produced in cells were also significantly reduced, while the viral RNA replication was down-regulated by a different level. Furthermore, viral entry into those cells was reduced by about 80%. CONCLUSIONS: Our data suggest that the function of Rab8 is important for DV2 infection, and Rab8 may be involved in DV2 infection.

Up-regulated expression of beta3 integrin induced by dengue virus serotype 2 infection associated with virus entry into human dermal microvascular endothelial cells.

Permeability alteration of microvascular endothelia is a factor in the plasma leakage produced by dengue virus (DV) infection, and beta3 integrin plays central roles in maintaining capillary integrity and regulating vascular permeability. In this study, interaction between beta3 integrin and DV serotype 2 (DV2) was investigated using human dermal microvascular endothelial cell line-1 (HMEC-1). We reported that DV2 infection could induce high expression level of beta3 integrin, and the high fluorescence intensity of beta3 integrin antigen observed in HMEC-1 after infection showed high co-localization with DV antigen. Pre-incubation of the virus with soluble alphanubeta3 integrin could strongly inhibit DV2 entry. And about 90% of virus entry was inhibited when beta3 integrin expression level was down-regulated by RNA interference. Our data indicated that DV2 infection could induce up-regulating expression of beta3 integrin, and beta3 integrin was required for DV2 entry into HMEC-1.

Dengue-specific CD8+ T cells have both protective and pathogenic roles in dengue virus infection.

To analyze roles of memory T cells in the pathogenesis of dengue (DEN) virus infection, a DEN virus-specific CD8+ cell clone (2D42 cell) was employed to investigate its in vivo function after DEN virus infection using an animal model. HepG2 grafted severe combined immunodeficient (HepG2-grafted SCID) mice were divided into three groups--group A: HepG2-grafted SCID mice were inoculated intraperitoneally (ip) with 2D42 cells and then ip-infected with DEN virus type 2 (DEN-2); group B: HepG2-grafted SCID mice were inoculated with naive mouse thymocytes (NMT) and then ip-infected with DEN-2; group C: HepG2-grafted SCID mice were ip-infected with DEN-2 alone. Eighty percentage of group A mice died at average day 12.8 post-infection (p.i.) and 20% of them recovered from the disease after showing clinical signs and survived more than 3 months. They showed severe manifestations including dramatically decreased platelet count, decreased hematocrit, anemia, viremia and high frequency of histopathological changes in several organs. All of group B mice also showed the above severe clinical signs. One hundred percentage mortality rate was noted in these mice and death occurred at average day 10.8 p.i., which was the earliest among three groups. Although the mice from group C showed 100% mortality rate and similar clinical signs, death observed in these mice occurred at average day 17.4 p.i. and the manifestations were slight and developed slowly. Our results suggested both protective and pathogenic roles for DEN-specific CD8+ T cell in DEN virus infection, whereas NMT did not provided any protection.