Structural insights into the substrate binding sites of O-carbamoyltransferase VtdB from Streptomyces sp. NO1W98.

The O-carbamoyltransferase VtdB catalyzes the carbamoylation of venturicidin B, which is essential for the biosynthesis of the antibiotic venturicidin A. Here, the crystal structures of VtdB and VtdB in complex with the intermediate carbamoyladenylate (VtdBCAO) were determined at resolutions of 2.99 Å and 2.90 Å, respectively. The structures resemble the conserved YrdC-like and specific Kae1-like domains. A magnesium ion and the intermediate carbamoyladenylate were also observed in the Kae1-like domain of VtdB. The structure of VtdBCAO in complex with the substrate venturicidin B was modeled by a molecular docking method to better understand the substrate binding mode, revealing a novel venturicidin B binding pocket.

The First Genomic Analysis of Visna/Maedi Virus Isolates in China.

Visna/Maedi virus (VMV) is a neglected pathogen that damages sheep and goats' nervous and respiratory systems. The virus was discovered 80 years ago and has been endemic in China for nearly four decades; nevertheless, there is little information regarding Chinese isolates' genotypes and genomic characteristics. In this study, the proviral DNA of strains isolated in 1985 and 1994 were extracted, and the proviral DNA was subjected to Illumina sequencing combined with Sanger sequencing of poor coverage regions. The results showed that the two isolates were clustered with genotype A2 and shared 78.3%-89.1% similarity to reference VMV genome sequences, with the highest similarity (88.7%-89.1%) to the USA strain USMARC-200212120-r (accession no. MT993908.1) and lowest similarity (78.3%-78.5%) to the Italian strain SRLV009 (accession no. MG554409.1). A maximum-likelihood tree showed that the Chinese VMV strains and the USA strain 1150 (accession no. MH916859.1) comprise a monophyletic group with a short tree branch. Our data filled the gap in genomic analysis and viral evolution in Chinese VMV strains, and would be benefit China's source-tracing and eradication program development in China.

Prevalence of Hepatitis E Virus (HEV) in Feral and Farmed Wild Boars in Xinjiang, Northwest China.

Hepatitis E virus (HEV) causes infections in humans and a wide range of animal hosts. Wild boar is an important natural reservoir of HEV genotypes 3−6 (HEV-3−HEV-6), but comparative analysis of HEV infections in both feral and farmed wild boars remains limited. In this study, samples from 599 wild boars were collected during 2017−2020, including 121 feral wild boars (collected 121 fecal, 121 serum, and 89 liver samples) and 478 farmed wild boars (collected 478 fecal and 478 serum samples). The presence of anti-HEV IgG antibodies were detected by the HEV-IgG enzyme-linked immunosorbent assay (ELISA) kit. HEV RNA was detected by reverse transcription polymerase chain reaction (RT-PCR), targeting the partial ORF1 genes from fecal and liver samples, and the obtained genes were further genotyped by phylogenetic analysis. The results showed that 76.2% (95% CI 72.1−79.9) of farmed wild boars tested anti-HEV IgG seropositive, higher than that in feral wild boars (42.1%, 95% CI 33.2−51.5, p < 0.001). HEV seropositivity increased with age. Wild boar HEV infection presented a significant geographical difference (p < 0.001), but not between sex (p = 0.656) and age (p = 0.347). HEV RNA in fecal samples was detected in 13 (2.2%, 95% CI 1.2−3.7) out of 599 wild boars: 0.8% (95% CI 0.0−4.5, 1/121) of feral wild boars and 2.5% (95% CI 1.3−4.3, 12/478) of farmed wild boars. Phylogenetic analysis showed that all these viruses belonged to genotype HEV-4, and further grouped into sub-genotypes HEV-4a, HEV-4d, and HEV-4h, of which HEV-4a was first discovered in the wild boar populations in China. Our results suggested that farms could be a setting for amplification of HEV. The risk of HEV zoonotic transmission via rearing and consumption of farmed wild boars should be further assessed.

m6A modification regulates lung fibroblast-to-myofibroblast transition through modulating KCNH6 mRNA translation.

Idiopathic pulmonary fibrosis (IPF) is a chronic, fatal lung disease characterized by progressive and non-reversible abnormal matrix deposition in lung parenchyma. Myofibroblasts originating mainly from resident fibroblasts via fibroblast-to-myofibroblast transition (FMT) are the dominant collagen-producing cells in pulmonary fibrosis. N6-methyladenosine (m6A) modification has been implicated in various biological processes. However, the role of m6A modification in pulmonary fibrosis remains elusive. In this study, we reveal that m6A modification is upregulated in a bleomycin (BLM)-induced pulmonary fibrosis mouse model, FMT-derived myofibroblasts, and IPF patient lung samples. Lowering m6A levels through silencing methyltransferase-like 3 (METTL3) inhibits the FMT process in vitro and in vivo. Mechanistically, KCNH6 is involved in the m6A-regulated FMT process. m6A modification regulates the expression of KCNH6 by modulating its translation in a YTH-domain family 1 (YTHDF1)-dependent manner. Together, our study highlights the critical role of m6A modification in pulmonary fibrosis. Manipulation of m6A modification through targeting METTL3 may become a promising strategy for the treatment of pulmonary fibrosis.

Seroprevalence of Five Zoonotic Pathogens in Wild Ruminants in Xinjiang, Northwest China.

Wild ruminants are at risk for zoonotic pathogen infection as a result of interactions with domestic animals and humans. One way to assess the level of a wild ruminant disease in a population is to determine the seroprevalence of the pathogen of interest. The objective of this study was to determine the seroprevalence of five zoonotic pathogens in wild ruminants in Xinjiang, Northwest China. In 2009 and 2011-2015, 258 wild ruminant sera samples were collected from various species. Samples were obtained from 30 Siberian ibexes, 94 goitered gazelles, 6 Tibetan antelopes, 32 argali sheep, 16 roe deer, 20 blue sheep, 56 red deer, and 4 wild yaks, in 10 regions of Xinjiang. Samples were tested using antibodies against Brucella spp., Chlamydophila abortus, Coxiella burnetii, Toxoplasma gondii, and West Nile virus. Seropositivity was detected for all five pathogens, with detection rates of Brucella spp., C. abortus, C. burnetii, T. gondii, and West Nile virus of 2.3% (95% confidence interval [CI], 0.5-4.2%), 6.2% (95% CI, 3.3-9.1%), 7.8% (95% CI, 4.5-11.0%), 2.3% (95% CI, 0.5-4.2%), and 0.8% (95% CI, 0-1.8%), respectively. The level of pathogens differed for different species and different regions. The results indicate that seropositivity to zoonotic pathogens is common among wild ruminants in Xinjiang, Northwest China, with C. burnetii and C. abortus detected at the highest levels. This study provides a baseline for future assessment of spillover events.

circHIPK3 regulates lung fibroblast-to-myofibroblast transition by functioning as a competing endogenous RNA.

Myofibroblasts predominantly emerging through fibroblast-to-myofibroblast transition (FMT) are considered to be the key collagen-producing cells in pulmonary fibrosis. Circular RNAs (circRNAs) are important players involved in many biological processes. circHIPK3 has been identified as the one of the most abundant circRNAs in human lung. In this study, we characterized the role of circHIPK3 in pulmonary fibrosis. We revealed that circHIPK3 is upregulated in bleomycin-induced pulmonary fibrosis mice model, FMT-derived myofibroblasts. circHIPK3 silencing can ameliorate FMT and suppress fibroblast proliferation in vivo and vitro. Fundamentally, circHIPK3 regulates FMT by functioning as an endogenous miR-338-3p sponge and inhibit miR-338-3p activity, thereby leading to increased SOX4 and COL1A1 expression. Moreover, dysregulated circHIPK3 expression was detected in the clinical samples of patients with idiopathic pulmonary fibrosis. Intervention of circHIPK3 may represent a promising therapy for pulmonary fibrosis.

Effect of Platelet-derived P-selectin on Neutrophil Recruitment in a Mouse Model of Sepsis-induced Acute Kidney Injury.

BACKGROUND: Acute kidney injury (AKI) is a severe disease in critically ill patients. Neutrophil infiltration into kidney was associated with the development of AKI, and P-selectin may be involved in the process of neutrophil recruitment in kidney. This study aimed to explore the potential effect of platelet-derived P-selectin on neutrophil recruitment in a mouse model of sepsis-induced AKI. METHODS: A total of 30 C57BL/6 male mice were divided into five groups (n = 6 in each): sham group, sepsis group, anti-Ly6G group, anti-P-selectin group, and platelet depletion group. Sepsis was induced by cecal ligation and puncture. Serum creatinine concentration and platelet activity were measured by biochemical detector and flow cytometry, respectively. Histological and pathological features were analyzed using hematoxylin-eosin (H&E) and immunohistochemistry (IHC) staining, respectively. Myeloperoxidase (MPO) activity was detected with MPO assay. Unpaired t-test was used for data analysis. RESULTS: Serum creatinine increased significantly in septic group compared to sham group (2.68 ± 0.27 mg/dl vs. 0.82 ± 0.19 mg/dl, t = 12.06, P = 0.0000) but attenuated in antibodies-treated animals compared to septic group (anti-Ly6G: 1.62 ± 0.30 mg/dl vs. 2.68 ± 0.27 mg/dl, t = 5.76, P = 0.0004; anti-P-selectin: 1.76 ± 0.31 mg/dl vs. 2.68 ± 0.27 mg/dl, t = 4.92, P = 0.0012; and platelet depletion: 1.93 ± 0.29 mg/dl vs. 2.68 ± 0.27 mg/dl, t = 4.14, P = 0.0032). Platelet amount significantly decreased compared to sham group (658.20 ± 60.64 × 109/L vs. 822.00 ± 48.60 × 109/L, t = 4.71, P = 0.0015) in septic mice, especially in platelet depletion group (240.80 ± 44.98 × 109/L vs. 822.00 ± 48.60 × 109/L, t = 19.63, P = 0.0000). P-selectin activity was significantly increased in septic group compared to sham group (16.54 ± 1.60% vs. 1.90 ± 0.29%, t = 15.64, P = 0.0000) but decreased significantly in platelet depletion group compared to septic group (3.62 ± 0.68% vs. 16.54 ± 1.60%, t = 12.89, P = 0.0002). IHC analysis shown that neutrophil infiltration increased in septic mice compared to sham group (36.67 ± 3.79% vs. 9.17 ± 1.61%, t = 11.58, P = 0.0003) and function-blocked groups (anti-Ly6G: 36.67 ± 3.79% vs. 15.33 ± 1.53%, t = 9.05, P = 0.0008; anti-P-selectin: 36.67 ± 3.79% vs. 21.33 ± 1.53%, t = 6.51, P = 0.0029; and platelet depletion: 36.67 ± 3.79% vs. 23.33 ± 3.06%, t = 4.75, P = 0.0090). MPO increased significantly in septic group compared to control (49.73 ± 1.83 ng/mg prot vs. 13.04 ± 2.16 ng/mg prot, t = 19.03, P = 0.0000) but decreased in function-blocked groups compared to septic group (anti-Ly6G: 26.52 ± 3.86 ng/mg prot vs. 49.73 ± 1.83 ng/mg prot, t = 9.59, P = 0.0000; anti-P-selectin: 33.06 ± 6.75 ng/mg prot vs. 49.73 ± 1.83 ng/mg prot, t = 4.85, P = 0.0013; and platelet depletion: 33.37 ± 2.25 ng/mg prot vs. 49.73 ± 1.83 ng/mg prot, t = 5.33, P = 0.0007). CONCLUSION: Platelets-derived P-selectin may be involved in the development of septic AKI through inducing neutrophil infiltration into kidney.

CARD9 gene silencing with siRNA protects rats against severe acute pancreatitis: CARD9-dependent NF-κB and P38MAPKs pathway.

We previously reported the up-regulation of caspase recruitment domain 9 (CARD9) expressions in severe acute pancreatitis (SAP) patients, but little is known about its regulation. In this study, small interfering RNA (siRNA) was used to reduce the levels of CARD9 expression in sodium taurocholate-stimulated SAP rats. CARD9 was overexpressed in SAP rats, which correlated with the severity of pancreatitis. When compared to the untreated group, the cohort that received the siRNA treatment demonstrated a significant reduction in pancreatic injury, neutrophil infiltration, myeloperoxidase activity and pro-inflammatory cytokines. Furthermore, siRNAs showed that the reduction of CARD9 in SAP rats down-regulated the expression of NF-κBp65 and P38MAPK which are involved in the transcription and release of a wide variety of inflammatory cytokines. These findings provide evidence that CARD9 is up-regulated in SAP rats and acts as a potential therapeutic target for the treatment thereof. Blocking the activation of NF-κB and P38MAPK via siRNA-mediated gene knock-down of CARD9 appears to reduce the inflammatory response in pancreatic tissue.

Oblongifolin C and guttiferone K extracted from Garcinia yunnanensis fruit synergistically induce apoptosis in human colorectal cancer cells in vitro.

Oblongifolin C (OC) and guttiferone K (GUTK) are two anticancer compounds extracted from Garcinia yunnanensis Hu, but they act by different mechanisms. In this study we investigated whether a combination of OC and GUTK (1:1 molar ratio) could produce synergistic anticancer effects against human colorectal cancer cells in vitro. For comparison, we also examined the anticancer efficacy of ethanol extracts from G yunnanensis fruit, which contain OC and GUTK up to 5%. Compared to OC and GUTK alone, the combination of OC and GUTK as well as the ethanol extracts more potently inhibited the cancer cell growth with IC50 values of 3.4 µmol/L and 3.85 µg/mL, respectively. Furthermore, OC and GUTK displayed synergistic inhibition on HCT116 cells: co-treatment with OC and GUTK induced more prominent apoptosis than treatment with either drug alone. Moreover, the combination of OC and GUTK markedly increased cleavage of casapse-3 and PARP, and enhanced cellular ROS production and increased JNK protein phosphorylation. In addition, the combination of OC and GUTK exerted stronger effects under nutrient-deprived conditions than in complete medium, suggesting that autophagy played an essential role in regulating OC- and GUTK-mediated cell death. OC and GUTK are the main components that contribute to the anticancer activity of G yunnanensis and the compounds have apoptosis-inducing effects in HCT116 cells in vitro.

Nujiangexathone A, a Novel Compound Derived from Garcinia nujiangensis, Induces Caspase-Dependent Apoptosis in Cervical Cancer through the ROS/JNK Pathway.

Nujiangexathone A (NJXA), a novel compound derived from Garcinia nujiangensis, has been demonstrated to inhibit the proliferation of several human cancer cell lines. This study is the first to demonstrate the apoptosis inductive activities of NJXA and the possible underlying mechanisms. Our results demonstrated that NJXA inhibited colony formation by HeLa and SiHa cells in a dose-dependent manner. An Annexin V-FITC/PI staining assay showed that NJXA strongly triggered apoptosis in a dose-dependent manner. Western blotting analyses showed that NJXA induced the caspase-dependent apoptosis of HeLa and SiHa cells by triggering a series of events, including changes in the levels of Bcl-2 family proteins, cytochrome c release, caspase-3 activation, and chromosome fragmentation. Furthermore, we demonstrated that NJXA induced cell apoptosis by activating the reactive oxygen species (ROS)-mediated JNK signaling pathway. Consistent with this finding, a ROS scavenger, N-acetyl-l-cysteine (NAC, 10 mM), hindered NJXA-induced apoptosis and attenuated the sensitivity of HeLa and SiHa cells to NJXA. In vivo results further confirmed that the tumor inhibitory effect of NJXA was partially through the induction of apoptosis. Taken together, our results demonstrated that NJXA induced the apoptosis of HeLa and SiHa cells through the ROS/JNK signaling pathway, indicating that NJXA could be important candidate for the clinical treatment of cervical cancer.

Implication of Unfolded Protein Response and Autophagy in the Treatment of BRAF Inhibitor Resistant Melanoma.

The continuous activation of the mitogen-activated protein kinase signaling cascade, typified by the BRAFV600E mutation, is one of the key alterations in melanoma. Accordingly, two BRAF inhibitors (BRAFi), vemurafenib and dabrafenib are utilized to treat melanoma and resulted in an excellent clinical outcome. However, the clinical success is not long-lasting, and the BRAFi resistance and disease progression inevitably occurs in nearly all patients. Endoplasmic reticulum stress-induced unfolded protein response and autophagy have emerged as potential pro-survival mechanisms adopted by melanoma cells in response to BRAFi. In this review, we discuss the role of unfolded protein response and autophagy that are implicated in the development of BRAFi-resistant melanoma and the corresponding strategy aiming at overcoming the intractable clinical problem.

Central role of neutrophil in the pathogenesis of severe acute pancreatitis.

Severe acute pancreatitis (SAP) is an acute abdominal disease with the strong systemic inflammatory response, and rapidly progresses from a local pancreatic damage into multiple organ dysfunction. For many decades, the contributions of neutrophils to the pathology of SAP were traditionally thought to be the chemokine and cytokine cascades that accompany inflammation. In this review, we focus mainly on those recently recognized aspects of neutrophils in SAP processes. First, emerging evidence suggests that therapeutic interventions targeting neutrophils significantly lower tissue damage and protect against the occurrence of pancreatitis. Second, trypsin activation promotes the initial neutrophils recruitment into local pancreas, and subsequently neutrophils infiltration in turn triggers trypsin production. Finally, neutrophils have the unique ability to release neutrophil extracellular traps even in the absence of pathogens.

ER stress-induced autophagy in melanoma.

The activation of RAF-MEK-extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase cascade by v-raf murine sarcoma viral oncogene homolog B1 (BRAF)(V600E) mutation is a key alteration in melanoma. Although BRAF inhibitor (BRAFi) has achieved remarkable clinical success, the positive response to BRAFi is not sustainable, and the initial clinical benefit is eventually barred by the development of resistance to BRAFi. There is growing evidence to suggest that endoplasmic reticulum (ER) stress-induced autophagy could be a potential pro-survival mechanism that contributes to genesis of melanoma and to the resistance to BRAFi. ER stress-induced autophagy is an evolutionarily conserved membrane process. By degrading and recycling proteins and organelles via the formation of autophagous vesicles and their fusion with lysosomes, the autophagy plays a key role in homeostasis as well as pathological processes. In this review, we examine the autophagy phenomenon in melanocytic nevus, primary and metastatic melanoma, and its significance in BRAFi-resistant melanoma.

Expression and significance of HIF-1α in pulmonary fibrosis induced by paraquat.

It is commonly accepted that epithelial-mesenchymal transition contributes to fibrotic remodeling, but the molecular pathways involved in paraquat (PQ)-induced epithelial-mesenchymal transition remain uncharacterized. The objective of this study was to evaluate the potential involvement of HIF-1α in TGF-ß1/ß-Catenin and Snail pathway after PQ poisoning. In our study, 86 Spragne-Dawley rats were randomly divided into control group and PQ group, which received intragastric infusion of 20% PQ solution 50 mg/kg. Rats in the PQ group were subsequently divided into eight subgroups (10 for each subgroup) and samples were collected at different predetermined time points (2, 6, 12, 24, 48, 72, 96 h and 7 d). Fibrosis markers, including ß-catenin, snail and α-SMA, were measured by western blot. The activity of HIF-1α was determined by western blot and immunofluorescence. We found that in PQ-induced pulmonary fibrosis, the level of PaO2 was significantly reduced in the 6-h subgroup, when compared to the control group (P < 0.01). Interestingly, between 6 and 72 h, there was no significant difference in PaO2. On the other hand, the level of PaCO2 started to increase from 72-h subgroup (P < 0.01). Fibrosis markers including ß-catenin, snail and α-SMA, measured by western blot, were significantly increased at 2 h, while the level of p-GSK-3ß was increased at 6 h. And the level of GSK-3ß showed significant reduction beginning at 24 h. The activity of HIF-1α measured by western blot assays was significantly increased starting from 2 h with sustained expression. The result of Pearson coefficient analysis showed that HIF-1α was positively correlated with Snail (r = 0.935, P < 0.01) and ß-catenin (r = 0.761, P < 0.05). Meanwhile, immunofluorescent analysis of HIF-1α revealed partial staining appearing from 2 h. Our data illustrated a positive correlation between Snail, ß-catenin signaling and HIF-1α, suggesting a potential synergistic role of HIF-1α in PQ-induced pulmonary fibrosis, which may be independent of GSK-3ß. It might also represent a potential therapeutic window for treatment of paraquat poisoning.

[The relationship of endoplasmic reticulum stress with paraquat induced lung fibrosis in rats].

OBJECTIVE: To investigate the relationship between pulmonary fibrosis and endoplasmic reticulum stress (ERS) in rats with paraquat poisoning. METHODS: One hundred male Sprague-Dawley (SD) rats were randomly divided into control group (n=10) and paraquat poisoning group (n=90). The animals were sacrificed by exsanguination at 2, 6, 12, 24, 48, 72, 96, 168, 336 hours after administration with 20% parquat solution. The paraffin sections of lung tissue were stained with hematoxylin-eosin (HE) and Masson trichrome to observe the pathological changes. Glucose-regulated protein 78 (GRP78) was determined by immunohistochemistry, and malondialdehyde (MDA) of lung tissue was measured. The total protein of tissue was abstracted, and the α-smooth muscle actin (α-SMA) and GRP78 was detected by Western blotting. RESULTS: HE and Masson staining demonstrated inflammatory infiltration and collagen deposition in the lung after paraquat administration with a tendency of exaggeration with time, and finally resulted in fibrosis. The expressions of MDA, α-SMA and GRP78 in the lung tissue were significantly increased 2 hours after paraquat administration compared with those of control group (MDA: 1.38 ± 0.18 nmol/mg vs. 0.85 ± 0.05 nmol/mg, α-SMA: 0.23 ± 0.01 vs. 0.14 ± 0.03, GRP78: 0.72 ± 0.02 vs. 0.37 ± 0.06, P<0.05 or P<0.01), and the expressions of MDA and α-SMA were gradually increased with time. GRP78 protein expression was decreased at 72 hours after paraquat administration. CONCLUSIONS: The results reveal that the expressions of α-SMA and GRP78 in paraquat poisoning group are up-regulated, suggesting ERS plays an important role in paraquat induced-pulmonary fibrosis.

Effect of ulinastatin on paraquat-induced-oxidative stress in human type II alveolar epithelial cells.

BACKGROUND: Ulinastatin (UTI) is a urinary trypsin inhibitor extracted and purified from urine of males. This study aimed to explore the effects of UTI on paraquat-induced-oxidative stress in human type II alveolar epithelial cells. METHODS: The human type II alveolar epithelial cells, A549 cells, were cultured in vitro. The A549 cells were treated with different concentrations of paraquat (200, 400, 600, 800, 1 000, 1 200 µmol/L) and ulinastatin(0, 2 000, 4 000, 6 000, 8 000 U/mL) for 24 hours, the cell viability was measured by cell counting kit-8 and the median lethal concentration was selected. In order to establish an in vitro model of paraquat intoxication and to determine the safe dose of ulinastatin, we calculated LD50 using cell counting kit-8 to determine the survival rate of the cells. A549 cells were divided into normal control group, paraquat group and paraquat+ulinastatin group. The levels of malondialdehyde (MDA) and myeloperoxidase (MPO) were detected by biochemistry colorimetry, while the level of reactive oxygen spies (ROS) was detected by DCFH-DA assay. RESULTS: The survival rate of A549 cells treated with different concentrations of paraquat decreased in a concentration-dependent manner. Whereas there was no decrease in the survival rate of cells treated with 0-4 000 U/mL ulinastatin. The levels of MDA, MPO, and ROS were significantly higher in the paraquat group than in the normal control group after 24-hour-exposure. And the survival rate of the paraquat+ulinastatin group was higher than that of the paraquat group, but lower than that of the normal control group. The levels of MDA, MPO, and ROS were lower than those of the paraquat group. CONCLUSION: Ulinastatin can alleviate the paraquat-induced A549 cell damage by reducing oxidative stress.