Hydroxylation with Unusual Stereoinversion Catalyzed by an FeII /2-OG Dependent Oxidase and 3,6-Diene-2,5-diketopiperazine Formation in the Biosynthesis of Brevianamide†K.

Natural products with the 3,6-diene-2,5-diketopiperazine core are widely distributed in nature; however, the biosynthetic mechanism of 3,6-diene-2,5-diketopiperazine in fungi remains to be further elucidated. Through heterologous expression and biochemical investigation of an FeII /2-oxoglutarate-dependent oxidase (AspE) and a heme-dependent P450 enzyme (AspF), we report that AspE, AspF and subsequent dehydration account for the formation of the 3,6-diene-2,5-diketopiperazine substructure of brevianamide K from Aspergillus sp. SK-28, a symbiotic fungus of mangrove plant Kandelia candel. More interestingly, in-depth investigation of the enzymatic mechanism showed that AspE promotes hydroxylation of brevianamide Q with unprecedented stereoinversion through hydrogen atom abstraction and water nucleophilic attack from the opposite face of the resultant iminium cation intermediate.

Discovery of Potent and Selective Dual Leucine Zipper Kinase/Leucine Zipper-Bearing Kinase Inhibitors with Neuroprotective Properties in In Vitro and In Vivo Models of Amyotrophic Lateral Sclerosis.

Dual leucine zipper kinase (DLK) and leucine zipper-bearing kinase (LZK) are regulators of neuronal degeneration and axon growth. Therefore, there is a considerable interest in developing DLK/LZK inhibitors for neurodegenerative diseases. Herein, we use ligand- and structure-based drug design approaches for identifying novel amino-pyrazine inhibitors of DLK/LZK. DN-1289 (14), a potent and selective dual DLK/LZK inhibitor, demonstrated excellent in vivo plasma half-life across species and is anticipated to freely penetrate the central nervous system with no brain impairment based on in vivo rodent pharmacokinetic studies and human in vitro transporter data. Proximal target engagement and disease relevant pathway biomarkers were also favorably regulated in an in vivo model of amyotrophic lateral sclerosis.

Inactivation of Nitrite-Dependent Nitric Oxide Biosynthesis Is Responsible for Overlapped Antibiotic Resistance between Naturally and Artificially Evolved Pseudomonas aeruginosa.

Metabolic flexibility of Pseudomonas aeruginosa could lead to new strategies to combat bacterial infection. The present study used gas chromatography-mass spectrometry (GC-MS)-based metabolomics to investigate global metabolism in naturally and artificially evolved strains with cefoperazone-sulbactam (SCF) resistance (AP-RCLIN-EVO and AP-RLAB-EVO, respectively) from the same parent strain (AP-RCLIN). Inactivation of the pyruvate cycle and nitric oxide (NO) biosynthesis was identified as characteristic features of SCF resistance in both evolved strains. Nitrite-dependent NO biosynthesis instead of an arginine-dependent NO pathway is responsible for the reduced NO, which is attributed to lower nitrite and electrons from the oxidation of NADH to NAD+ provided by the pyruvate cycle. Exogenous fumarate, NADH, nitrate, and nitrite promoted the NO level and thereby potentiated SCF-mediated killing. Unexpectedly, fumarate caused the elevation of nitrite, while nitrite/nitrate resulted in the increase of Cyt bc1 complex (providing electrons). These interesting findings indicate that the nitrite-dependent NO biosynthesis and the pyruvate cycle are mutual to promote NO metabolism. In addition, the NO-potentiated sensitivity to SCF was validated by NO donor sodium nitroprusside. These results reveal an endogenous NO-mediated SCF resistance and develop its reversion by metabolites in P. aeruginosa. IMPORTANCE Infections with Pseudomonas aeruginosa have become a real concern among hospital-acquired infections, especially in cystic fibrosis patients and immunocompromised individuals. Control of the pathogen is challenging due to antibiotic resistance. Since bacterial metabolic state impacts sensitivity and resistance to antibiotics, exploring and disclosing bacterial metabolic mechanisms can be used to develop a metabolome-reprogramming approach to elevate bacterial sensitivity to antibiotics. Therefore, GC-MS-based metabolomics is used to explore the similarities and differences of metabolomes between naturally and artificially evolved cefoperazone-sulbactam (SCF)-resistant P. aeruginosa (AP-RCLIN-EVO and AP-RLAB-EVO, respectively) from the same parent strain (AP-RCLIN). It identifies the depressed nitrite-dependent nitric oxide (NO) biosynthesis as the most overlapping characteristic feature between AP-RCLIN-EVO and AP-RLAB-EVO. This is because the pyruvate cycle fluctuates, thereby generating fewer NADH and providing fewer electrons for nitrite-dependent NO biosynthesis than the control. Interestingly, exogenous fumarate, NADH, nitrate, and nitrite as well as NO donor sodium nitroprusside promote NO generation to elevate sensitivity to SCF. These results highlight the way to understand metabolic mechanisms of antibiotic resistance and explore metabolic modulation to combat the bacterial pathogen.

Low Dimensional Discriminative Representation of Fully Connected Layer Features Using Extended LargeVis Method for High-Resolution Remote Sensing Image Retrieval.

Recently, there have been rapid advances in high-resolution remote sensing image retrieval, which plays an important role in remote sensing data management and utilization. For content-based remote sensing image retrieval, low-dimensional, representative and discriminative features are essential to ensure good retrieval accuracy and speed. Dimensionality reduction is one of the important solutions to improve the quality of features in image retrieval, in which LargeVis is an effective algorithm specifically designed for Big Data visualization. Here, an extended LargeVis (E-LargeVis) dimensionality reduction method for high-resolution remote sensing image retrieval is proposed. This can realize the dimensionality reduction of single high-dimensional data by modeling the implicit mapping relationship between LargeVis high-dimensional data and low-dimensional data with support vector regression. An effective high-resolution remote sensing image retrieval method is proposed to obtain stronger representative and discriminative deep features. First, the fully connected layer features are extracted using a channel attention-based ResNet50 as a backbone network. Then, E-LargeVis is used to reduce the dimensionality of the fully connected features to obtain a low-dimensional discriminative representation. Finally, L2 distance is computed for similarity measurement to realize the retrieval of high-resolution remote sensing images. The experimental results on four high-resolution remote sensing image datasets, including UCM, RS19, RSSCN7, and AID, show that for various convolutional neural network architectures, the proposed E-LargeVis can effectively improve retrieval performance, far exceeding other dimensionality reduction methods.

circRNA-miRNA-mRNA regulatory network in human lung cancer: an update.

Circular RNAs, as hopeful diagnosis markers and therapeutic molecules, have been studied, probed and applied into several diseases, such as cardiovascular diseases, systemic lupus erythematosus, leukemia, pulmonary tuberculosis, and cancer especially. Recently, mounting evidence has supported that circRNAs play a key role in the tumorigenesis, progress, invasion and metastasis in lung cancer. Its special structure-3'-5' covalent loop-allow it to execute several special functions in both normal eukaryotic cells and cancer cells. Our review summaries the latest studies on characteristics and biogenesis of circRNAs, and highlight the regulatory functions about miRNA sponge of lung-cancer-related circRNAs. In addition, the interaction of the circRNA-miRNA-mRNA regulatory network will also be elaborated in detail in this review. Therefore, this review can provide a new idea or strategy for further development and application in clinical setting in terms of early-diagnosis and better treatment.

IL-37 alleviates house dust mite-induced chronic allergic asthma by targeting TSLP through the NF-κB and ERK1/2 signaling pathways.

Interleukin (IL)-37 has been described as a negative regulator of immune responses and is critical for asthma pathogenesis, but the mechanisms behind the protective role of IL-37 against allergic asthma are less well understood. We show here that IL-37 administered intranasally inhibited house dust mite (HDM)-induced chronic airway eosinophilic inflammation, goblet cell hyperplasia, peribronchial collagen deposition and airway hyperresponsiveness (AHR) to methacholine. In contrast to a weakened Th2 response in the lung that was characterized by the downregulation of Th2-associated cytokines and chemokines in IL-37-treated mice, IL-37 has no effect on relevant markers of systemic Th2 immune including serum immunoglobulins expression and in vitro production of Th2-associated cytokines by splenocytes on HDM recall. We demonstrated that the production of thymic stromal lymphopoietin (TSLP) in the lung tissue was associated with IL-37. Importantly, compared with IL-37 alone, TSLP coadministration with IL-37 restored HDM-induced airway inflammation and structural alterations, increased AHR to methacholine and promoted Th2-associated cytokine production. We further found that IL-37 inhibited the induction of TSLP expression by the main antigen of house dust mite, Der p1, by suppressing NF-κB and extracellular signal regulated kinase 1/2 (ERK1/2) activation in human bronchial epithelial (16-HBE) cells in vitro. These data highlight the importance of TSLP in IL-37-mediated protective role in asthma. IL-37 might represent a useful innovative and alternative therapy to control TSLP production in the airway.

Medical Applications of Collagen and Hyaluronan in Regenerative Medicine.

In order to develop and commercialize for the regenerative medicinal products, smart biomaterials with biocompatibility must be needed. In this chapter, we introduce collagen and hyaluronic acid (HA) as extracellular matrix as well as deal with the molecular mechanism as microenvironment, mechanistic effects, and gene expression. Application of collagen and HA have been reviewed in the area of orthopedics, orthopedics, ophthalmology, dermatology and plastic surgery. Finally, the ongoing and commercial products of collagen and HA for regenerative medicine have been introduced.

Induction of apoptosis in human peritoneal mesothelial cells by gastric cancer cell supernatant promotes peritoneal carcinomatosis.

This study was carried out to evaluate the effects of gastric cancer cell supernatant on human peritoneal mesothelial cell viability and apoptosis and to investigate the mechanism of action of gastric cancer in a mesothelial cell line (HMrSV5). Cell viability was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazoliumbromide (MTT) assay. Mesothelial cells treated with gastric cancer cell supernatant were stained with acridine orange/ethidium bromide and subjected to fluorescence microscopy. C57BL/6 mice were used to establish a cancer invasion model. Morphological changes and exfoliation occurred, and naked areas appeared in both cultured mesothelial cells and the parietal peritoneum after treatment with gastric cancer cell supernatant. Cell supernatant from gastric cancer cells induced apoptosis of mesothelial cells in a time-dependent manner. Obvious morphological changes of cell apoptosis were detected, such as condensation of chromatin, nuclear fragmentations, and apoptotic ladders. These findings demonstrate that gastric cancer cells induce apoptosis of human peritoneal mesothelial cells through supernatants in early peritoneal metastasis.