Blocking protease-activated receptor 4 alleviates liver injury induced by brain death.

Brain death (BD) induces a systemic inflammatory response that influences donor liver quality. Protease-activated receptor 4 (PAR4) is a thrombin receptor that mediates platelet activation and is involved in inflammatory and apoptotic processes. Therefore, we investigated the role of PAR4 blockade in liver injury induced by BD and its associated mechanisms. In this study, we constructed a BD rat model and treated rats with TcY-NH2, a selective PAR4 antagonist, to block PAR4 signaling at the onset of BD induction. Our results revealed that PAR4 protein expression increased in the livers of rats with BD. PAR4 blockade alleviated liver injury induced by BD, as indicated by lower serum ALT/AST levels and an improvement in histomorphology. Blood platelet activation and hepatic platelet accumulation in BD rats were reduced by PAR4 blockade. Additionally, PAR4 blockade attenuated the inflammatory response and apoptosis in the livers of BD rats. Moreover, the activation of NF-κB and MAPK pathways induced by BD was inhibited by PAR4 blockade. Thus, our results suggest that PAR4 contributes to liver injury induced by BD by regulating inflammation and apoptosis through the NF-κB and MAPK pathways. Thus, PAR4 blockade may provide a feasible approach to improve the quality of organs from BD donors.

High expression of DHX9 promotes the growth and metastasis of hepatocellular carcinoma.

BACKGROUND: DHX9, an NTP-dependent RNA helicase, is closely associated with the proliferation and metastasis of some tumor cells and the prognosis of patients, but its role in hepatocellular carcinoma (HCC) is not well-known. This study was performed to explore the expression and role of DHX9 in HCC. METHODS: The expression of DHX9 in HCC tissues and cell lines was detected by TCGA database, qPCR, western blotting, and immunohistochemistry. The relationship between the DHX9 expression level and the prognosis of patients with HCC was accessed. Then, the function of DHX9 knockdown in HCC cells was examined by CCK-8, scratch, Transwell, and apoptosis assays. Epithelial-mesenchymal transition (EMT) was detected by western blotting. RESULTS: DHX9 was highly expressed in HCC tissues by analyzing both TCGA database and clinical samples. High DHX9 expression level was associated with TNM stage, vascular invasion and metastasis of HCC patients, and was an independent adverse prognostic factor. DHX9 knockdown significantly inhibited cell proliferation, migration, invasion and EMT and increased cell apoptosis in HCC cells. CONCLUSION: Our findings suggest that DHX9 participates in the progression of HCC as an oncogene and may be a potential target for the clinical diagnosis and therapy of HCC.

ENO3 Inhibits Growth and Metastasis of Hepatocellular Carcinoma via Wnt/ß-Catenin Signaling Pathway.

ß-enolase (ENO3) is a metalloenzyme that functions during glycolysis and has been revealed ectopic expression in different cancers. However, the function and underlying modulatory mechanisms of ENO3 in hepatocellular carcinoma (HCC) are still elusive. Here, we discovered that ENO3 was remarkably down-regulated in human HCC tissue in contrast to those in noncancerous tissue. Moreover, low expression of ENO3 was related to the poor prognosis of HCC patients. Overexpression of ENO3 suppressed proliferative, migratory, and invasive abilities of HCC cells both in vitro and in vivo, whereas knocking down ENO3 led to the opposite effect. In addition, we revealed that ENO3 repressed the epithelial-mesenchymal transition (EMT) process with its biomarker variations. Mechanistic research unveiled that ENO3 suppressed the Wnt/ß-catenin signal, which subsequently modulated the transcription of its target genes associated with the proliferation and metastasis capacity of HCC cells. Taken together, our study uncovered that ENO3 acted as a tumor inhibitor in HCC development and implied ENO3 as a promising candidate for HCC treatment.

The Postfusion Structure of the Heartland Virus Gc Glycoprotein Supports Taxonomic Separation of the Bunyaviral Families Phenuiviridae and Hantaviridae.

Heartland virus (HRTV) is an emerging human pathogen that belongs to the newly defined family Phenuiviridae, order Bunyavirales Gn and Gc are two viral surface glycoproteins encoded by the M segment and are required for early events during infection. HRTV delivers its genome into the cytoplasm by fusion of the viral envelope and endosomal membranes under low-pH conditions. Here, we describe the crystal structure of HRTV Gc in its postfusion conformation. The structure shows that Gc displays a typical class II fusion protein conformation, and the overall structure is identical to severe fever with thrombocytopenia syndrome virus (SFTSV) Gc, which also belongs to the Phenuiviridae family. However, our structural analysis indicates that the hantavirus Gc presents distinct features in the aspects of subdomain orientation, N-linked glycosylation, the interaction pattern between protomers, and the fusion loop conformation. This suggests their family-specific subunit arrangement during the fusogenic process and supports the recent taxonomic revision of bunyaviruses. Our results provide insights into the comprehensive comparison of class II membrane fusion proteins in two bunyavirus families, yielding valuable information for treatments against these human pathogens.IMPORTANCE HRTV is an insect-borne virus found in America that can infect humans. It belongs to the newly defined family Phenuiviridae, order Bunyavirales HRTV contains three single-stranded RNA segments (L, M, and S). The M segment of the virus encodes a polyprotein precursor that is cleaved into two glycoproteins, Gn and Gc. Gc is a fusion protein facilitating virus entry into host cells. Here, we report the crystal structure of the HRTV Gc protein. The structure displays a typical class II fusion protein conformation. Comparison of HRTV Gc with a recently solved structure of another bunyavirus Gc revealed that these Gc structures display a newly defined family specificity, supporting the recent International Committee on Taxonomy of Viruses reclassification of the bunyaviruses. Our results expand the knowledge of bunyavirus fusion proteins and help us to understand bunyavirus characterizations. This study provides useful information to improve protection against and therapies for bunyavirus infections.

Structures of phlebovirus glycoprotein Gn and identification of a neutralizing antibody epitope.

Severe fever with thrombocytopenia syndrome virus (SFTSV) and Rift Valley fever virus (RVFV) are two arthropod-borne phleboviruses in the Bunyaviridae family, which cause severe illness in humans and animals. Glycoprotein N (Gn) is one of the envelope proteins on the virus surface and is a major antigenic component. Despite its importance for virus entry and fusion, the molecular features of the phleboviruse Gn were unknown. Here, we present the crystal structures of the Gn head domain from both SFTSV and RVFV, which display a similar compact triangular shape overall, while the three subdomains (domains I, II, and III) making up the Gn head display different arrangements. Ten cysteines in the Gn stem region are conserved among phleboviruses, four of which are responsible for Gn dimerization, as revealed in this study, and they are highly conserved for all members in Bunyaviridae Therefore, we propose an anchoring mode on the viral surface. The complex structure of the SFTSV Gn head and human neutralizing antibody MAb 4-5 reveals that helices α6 in subdomain III is the key component for neutralization. Importantly, the structure indicates that domain III is an ideal region recognized by specific neutralizing antibodies, while domain II is probably recognized by broadly neutralizing antibodies. Collectively, Gn is a desirable vaccine target, and our data provide a molecular basis for the rational design of vaccines against the diseases caused by phleboviruses and a model for bunyavirus Gn embedding on the viral surface.

Attenuation of highly pathogenic porcine reproductive and respiratory syndrome virus by inserting an additional transcription unit.

Transcription regulatory sequences (TRSs) play a key role in the synthesis of porcine reproductive and respiratory syndrome virus (PRRSV) subgenomic mRNAs, which resembles similarity-assisted RNA recombination. In this study, genome instability was found when a highly pathogenic PRRSV (HP-PRRSV) strain was inserted by an additional transcription unit in which a foreign gene GFP was expressed from TRS2 while a copy of TRS6 drove ORF2a/b transcription. Structural protein gene-deleted genomes resulted from enhanced RNA recombinations were identified in the recombinant virus rHV-GFP. Moreover, rHV-GFP replicated slower than parental viruses, and caused less cell death in porcine alveolar macrophages. Pigs infected with rHV-GFP survived with no or mild syndromes, whereas all pigs infected with parental viruses died within 12 days. Our data showed that additional transcription unit insertion could confer genome instability and attenuation of HP-PRRSV.

The N-terminal domain of PA from bat-derived influenza-like virus H17N10 has endonuclease activity.

Influenza imposes a great burden on society, not only in its seasonal appearance that affects both humans and domesticated animals but also through the constant threat of potential pandemics. Migratory birds are considered to be the reservoir hosts for influenza viruses, but other animals must also be considered. The recently identified influenza-like virus genome, from H17N10 in bats, was shown to be markedly different from genomes of other known influenza viruses, as both its surface glycoproteins hemagglutinin (HA) and neuraminidase (NA) do not have canonical functions. However, no studies on other individual proteins from this particular virus have been reported until now. Here, we describe the structure of the N-terminal domain of PA from H17N10 influenza-like virus at 2.7-Å resolution and show that it has a fold similar to those of homologous PA domains present in more familiar influenza A virus strains. Moreover, we demonstrate that it possesses endonuclease activity and that the histidine residue in the active site is essential for this activity. Although this particular influenza virus subtype is probably not infectious for humans (even its virus state has not been confirmed in bats, as only the genome has been sequenced), reassortment of canonical influenza viruses with certain segments from H17N10 cannot be ruled out at this stage. Therefore, further studies are urgently needed for the sake of influenza prevention and control.

A novel method of terahertz spectroscopy and imaging in reflection geometry.

In reflection geometry of terahertz spectroscopy, the biological sample is usually placed on a sample window. This paper presents a novel method for eliminating the effect of the ringing, i.e., the interference between reflections of the reference and the sample, and from the air-window and sample-window interfaces, respectively. In the proposed method, a special thickness of substrate is designed to acquire an accurate reference reflection. The reflections of the samples of deionized water and ethanol were examined, and the calculation of optical properties of the samples by using our proposed method agrees with standard data. The main advantages of this method are simplicity, accuracy, and ease of application for reflection systems with different incident angles.

The use of levoglucosenone and isolevoglucosenone as templates for the construction of C-linked disaccharides.

Because of their functionalities (enone, ketone, and acetal) and their bicyclic structure (steric factors), levoglucosenone (1,6-anhydro-3,4-dideoxy-beta-D-glycero-hex-3-enopyran-2-ulose) and isolevoglucosenone (1,6-anhydro-2,3-dideoxy-beta-D-glycero-hex-3-enopyran-4-ulose) are useful templates for the convergent and combinatorial synthesis of (1-->2), (1-->3), and (1-->4)-linked C-disaccharides in reactions combining them with sugar-derived carbaldehydes. Synthetic methods relying on conjugate nucleophilic additions of these enones, their combination with aluminum reagents and aldehydes (Baylis-Hillman reaction) and modified Takai-Hiyama-Nozaki-Kishi couplings of enol triflates derived from them with sugar-derived aldehydes are reviewed. Highly stereoselective methods have thus been developed. These allow the generation of disaccharide mimetics with a high molecular diversity.