PEDF inhibits VEGF-induced vascular leakage through binding to VEGFR2 in acute myocardial infarction.

Pigment epithelium-derived factor (PEDF) could bind to vascular endothelial growth factor receptor 2 (VEGFR2) and inhibit its activation induced by VEGF. But how PEDF affects VEGFR2 pathway is still poorly understood. In this study, we elucidated the precise mechanism underlying the interaction between PEDF and VEGFR2, and subsequently corroborated our findings using a rat AMI model. PEDF prevented endocytosis of VE-cadherin induced by hypoxia, thereby protecting the endothelium integrity. A three-dimensional model of the VEGFR2-PEDF complex was constructed by protein-protein docking method. The results showed that the VEGFR2-PEDF complex was stable during the simulation. Hydrogen bonds, binding energy and binding modes were analyzed during molecular dynamics simulations, which indicated that hydrogen bonds and hydrophobic interactions were important for the recognition of VEGFR2 with PEDF. In addition, the results from exudation of fibrinogen suggested that PEDF inhibits vascular leakage in acute myocardial infarction and confirmed the critical role of key amino acids in the regulation of endothelial cell permeability. This observation is also supported by echocardiography studies showing that the 34mer peptide sustained cardiac function during acute myocardial infarction. Besides, PEDF and 34mer could inhibit the aggregation of myofiber in the heart and promoted the formation of a dense cell layer in cardiomyocytes, which suggested that PEDF and 34mer peptide protect against AMI-induced cardiac dysfunction. These results suggest that PEDF inhibits the phosphorylation of downstream proteins, thereby preventing vascular leakage, which provides a new therapeutic direction for the treatment of acute myocardial infarction.Communicated by Ramaswamy H. Sarma.

[Taxonomic and Functional Diversity of Soil Microbial Communities in Subalpine Meadow with Different Degradation Degrees in Mount Wutai].

Although soil microbes play a key role in grassland ecosystem functioning, the response of their diversity to grassland degradation has not been fully investigated. Here, we used shotgun metagenomic sequencing to analyze the characteristics and influencing factors of soil microbial taxonomic and functional diversity at four different degradation stages[i.e., non-degraded (ND), lightly degraded (LD), moderately degraded (MD), and heavily degraded (HD)]of subalpine meadow in the Mount Wutai. The results showed that there were significant differences in the relative abundances of Actinobacteria, Bacteroidetes, Nitrospirae, and Parcubacteria among the four subalpine grasslands with different degradation degrees (P<0.05).Compared with that in ND, the degraded meadows increased the proportion of genes related to carbon metabolism, biosynthesis of amino acids, pyruvate metabolism, citric acid cycle, propanoate metabolism, butanoate metabolism, and fatty acid metabolism (P<0.05), indicating that the degradation of subalpine grassland changed the metabolic potential of energy metabolism and the nutrient cycle of the soil microbial community. Grassland degradation changed soil microbial taxonomic and functional α diversity, especially in MD and HD.Grassland degradation resulted in significant changes in the taxonomic and functional compositions of the microbial communities. The total nitrogen, pH, and soil organic carbon significantly affected the taxonomic and functional compositions of the microbial communities.The ß diversity of the plant community was significantly correlated with the taxonomic and functional ß diversity of the microbial community (P<0.05), indicating strong coupling. The results of this study revealed the changes and driving mechanisms of subsurface microbial taxonomic and functional diversity during grassland degradation, which can provide a theoretical basis for subalpine meadow protection and ecological restoration.

Labdane diterpenoids from the heartwood of Leucosceptrum canum that impact on root growth and seed germination of Arabidopsis thaliana.

Eleven undescribed diterpenoids possessing labdane, 3,18-cyclo-labdane, 19 (4 â†’ 3)-labdane and 12-nor-labdane skeletons, named leucolactones A-K, were isolated from the heartwood of a large woody Lamiaceae plant, Leucosceptrum canum. Their structures were determined by NMR, MS, and in the case of leucolactones A by single crystal X-ray diffraction analysis. Plausible biosynthetic pathway of leucolactones were proposed. Leucolactones showed significant inhibitory effects against seed germination and root elongation of Arabidopsis thaliana in the Petri dish bioassay. Among them, the diastereomeric leucolactones G and H were the most potent, with EC50 values for root elongation of 6.53 ± 1.35 and 9.75 ± 1.25 µM, respectively. The preliminary structure-activity relationship of leucolactones was discussed. The increase of auxin reporter activity in A. thaliana DR5::GUS roots by leucolactone H was observed, indicating that leucolactones altered auxin accumulation and distribution. These findings suggested that leucolactones might be involved in regulation of plant growth and development through altering auxin accumulation and distribution, presumably contributing to the heartwood formation in L. canum.

Hepatoprotective Effect of Oplopanax elatus Nakai Adventitious Roots Extract by Regulating CYP450 and PPAR Signaling Pathway.

O. elatus Nakai is a traditional medicine that has been confirmed to exert effective antioxidant and anti-inflammatory functions, and is used for the treatment of different disorders. However, its potential beneficial effects on drug induced hepatotoxicity and relevant molecular mechanisms remain unclear. This study investigated the protective effect and further elucidated the mechanisms of action of O. elatus on liver protection. O. elatus chlorogenic acids-enriched fraction (OEB), which included chlorogenic acid and isochlorogenic acid A, were identified by HPLC-MS/MS. OEB was administrated orally daily for seven consecutive days, followed by a single intraperitoneal injection of an overdose of APAP after the final OEB administration. The effects of OEB on immune cells in mice liver were analyzed using flow cytometry. APAP metabolite content in serum was detected using HPLC-MS/MS in order to investigate whether OEB affects CYP450 activities. The intestinal content samples were processed for 16 s microbiota sequencing. Results demonstrated that OEB decreased alanine aminotransferase, aspartate aminotransferase contents, affected the metabolism of APAP, and decreased the concentrates of APAP, APAP-CYS and APAP-NAC by inhibiting CYP2E1 and CYP3A11 activity. Furthermore, OEB pretreatment regulated lipid metabolism by affecting the peroxisome proliferator-activated receptors (PPAR) signaling pathway in mice and also increased the abundance of Akkermansia and Parabacteroides. This study indicated that OEB is a potential drug candidate for treating hepatotoxicity because of its ability to affect drug metabolism and regulate lipid metabolism.

Hepatic Vps33b deficiency aggravates cholic acid-induced cholestatic liver injury in male mice.

Vacuolar protein sorting 33B (VPS33B) is important for intracellular vesicular trafficking process and protein interactions, which is closely associated with the arthrogryposis, renal dysfunction, and cholestasis syndrome. Our previous study has shown a crucial role of Vps33b in regulating metabolisms of bile acids and lipids in hepatic Vps33b deficiency mice with normal chow, but it remains unknown whether VPS33B could contribute to cholestatic liver injury. In this study we investigated the effects of hepatic Vps33b deficiency on bile acid metabolism and liver function in intrahepatic cholestatic mice. Cholestasis was induced in Vps33b hepatic knockout and wild-type male mice by feeding 1% CA chow diet for 5 consecutive days. We showed that compared with the wild-type mice, hepatic Vps33b deficiency greatly exacerbated CA-induced cholestatic liver injury as shown in markedly increased serum ALT, AST, and ALP activities, serum levels of total bilirubin, and total bile acid, as well as severe hepatocytes necrosis and inflammatory infiltration. Target metabolomics analysis revealed that hepatic Vps33b deficiency caused abnormal profiles of bile acids in cholestasis mice, evidenced by the upregulation of conjugated bile acids in serum, liver, and bile. We further demonstrated that the metabolomics alternation was accompanied by gene expression changes in bile acid metabolizing enzymes and transporters including Cyp3a11, Ugt1a1, Ntcp, Oatp1b1, Bsep, and Mrp2. Overall, these results suggest a crucial role of hepatic Vps33b deficiency in exacerbating cholestasis and liver injury, which is associated with the altered metabolism of bile acids.

PXR mediates mifepristone-induced hepatomegaly in mice.

Mifepristone (Mif), an effective synthetic steroidal antiprogesterone drug, is widely used for medical abortion and pregnancy prevention. Due to its anti-glucocorticoid effect, high-dose Mif is also used to treat Cushing's syndrome. Mif was reported to active pregnane X receptor (PXR) in vitro and PXR can induce hepatomegaly via activation and interaction with yes-associated protein (YAP) pathway. High-dose Mif was reported to induce hepatomegaly in rats and mice, but the underlying mechanism remains unclear. Here, the role of PXR was studied in Mif-induced hepatomegaly in C57BL/6 mice and Pxr-knockout mice. The results demonstrated that high-dose Mif (100 mg · kg-1 · d-1, i.p.) treatment for 5 days significantly induced hepatomegaly with enlarged hepatocytes and promoted proliferation, but low dose of Mif (5 mg · kg-1 · d-1, i.p.) cannot induce hepatomegaly. The dual-luciferase reporter gene assays showed that Mif can activate human PXR in a concentration-dependent manner. In addition, Mif could promote nuclear translocation of PXR and YAP, and significantly induced the expression of PXR, YAP, and their target proteins such as CYP3A11, CYP2B10, UGT1A1, ANKRD, and CTGF. However, Mif (100 mg · kg-1 · d-1, i.p.) failed to induce hepatomegaly in Pxr-knockout mice, as well as hepatocyte enlargement and proliferation, further indicating that Mif-induced hepatomegaly is PXR-dependent. In summary, this study demonstrated that PXR-mediated Mif-induced hepatomegaly in mice probably via activation of YAP pathway. This study provides new insights in Mif-induced hepatomegaly, and provides novel evidence on the crucial function of PXR in liver enlargement and regeneration.

Differentially expressed circRNA and functional pathways in the hippocampus of epileptic mice based on next-generation sequencing.

Epilepsy is a clinical syndrome caused by the highly synchronized abnormal discharge of brain neurons. It has the characteristics of paroxysmal, transient, repetitive, and stereotyped. Circular RNAs (circRNAs) are a recently discovered type of noncoding RNA with diverse cellular functions related to their excellent stability; additionally, some circRNAs can bind and regulate microRNAs (miRNAs). The present study was designed to screen the differentially expressed circRNA in an acute seizure model of epilepsy in mice, analyze the related miRNA and mRNA, and study their participating functions and enrichment pathways. In order to obtain the differential expression of circRNA in epilepsy and infer their function, we used next-generation sequencing and found significantly different transcripts. CIRI (circRNA identifier) software was used to predict circRNA from the hippocampus cDNA, EdgeR was applied for the differential circRNA analysis between samples, and Cytoscape 3.7.2 software was used to draw the network diagram. A total of 10,388 differentially expressed circRNAs were identified, of which 34 were upregulated and 66 were downregulated. Among them, mm9_circ_008777 and mm9_circ_004424 were the key upregulated genes, and their expression in the epilepsy group was verified using Quantitative real-time PCR (QPCR). The analysis indicated that the extracted gene ontology terms and Kyoto Encyclopedia of Genes and Genomes pathways were closely related to several epilepsy-associated processes. This study determined that mm9_circ_008777 and mm9_circ_004424 are potential biomarkers of epilepsy, which play important roles in epilepsy-related pathways. These results could help improve the understanding of the biological mechanisms of circRNAs and epilepsy treatments.

Schisandrol B promotes liver enlargement via activation of PXR and YAP pathways in mice.

BACKGROUND: Schisandrol B (SolB) is one of the bioactive components from a traditional Chinese medicine Schisandra chinensis or Schisandra sphenanthera. It has been demonstrated that SolB exerts hepatoprotective effects against drug-induced liver injury and promotes liver regeneration. It was found that SolB can induce hepatomegaly but the involved mechanisms remain unknown. PURPOSE: This study aimed to explore the mechanisms involved in SolB-induced hepatomegaly. METHODS: Male C57BL/6 mice were injected intraperitoneally with SolB (100 mg/kg) for 5 days. Serum and liver samples were collected for biochemical and histological analyses. The mechanisms of SolB were investigated by qRT-PCR and western blot analyses, luciferase reporter gene assays and immunofluorescence. RESULTS: SolB significantly increased hepatocyte size and proliferation, and then promoted liver enlargement without liver injury and inflammation. SolB transactivated human PXR, activated PXR in mice and upregulated hepatic expression of its downstream proteins, such as CYP3A11, CYP2B10 and UGT1A1. SolB also significantly enhanced nuclear translocation of PXR and YAP in human cell lines. YAP signal pathway was activated by SolB in mice. CONCLUSION: These findings demonstrated that SolB can significantly induce liver enlargement, which is associated with the activation of PXR and YAP pathways.

[Chemical constituents of Taxus chinensis var. mairei cell cultures].

The chemical constituents of Taxus chinensis var. mairei cell cultures were investigated by chromatographic methods, including silica gel column chromatography, Sephadex LH-20 and preparative HPLC. Thirteen compounds were isolated from the 80% ethanol extract of cultured cells and their structures were elucidated by spectral data and physicochemical properties, which were identified as 2α,4α,7ß,9α,10ß-pentaacetoxy-14ß-hydroxytax-11-ene (1), 2α,4α,7ß,9α,10ß-pentaacetoxytax-11-ene (2), 1ß-deoxybaccatin VI (3), 2α-acetoxytaxusin (4), taxuyunnanine C (5), yunnanxane (6), 2α,5α,10ß-triacetoxy-14ß-propionyloxy-4 (20), 11-taxadiene (7), 2α,5α,10ß-triacetoxy-14ß-isobutyryloxy-4 (20), 11-taxadiene (8), 2α,5α,10ß-triacetoxy-14ß-(2'-methyl)butyryloxy-4 (20), 11-taxadiene (9), 13-dehydroxylbaccatin III (10), 13-dehydroxy-10-deacetylbaccatin III (11), paclitaxel (12) and (13) ß-sitosterol. Among them, compound 1 is a new compound, and compounds 2, 4, 10 and 11 are isolated from the cell culture of Taxus chinensis var. mairei for the first time.

Defense sesterterpenoid lactones from Leucosceptrum canum.

Ten sesterterpenoids, leucosceptroids E-N (1-10), possessing an α,ß-unsaturated γ-lactone moiety, were isolated from the leaves and flowers of a woody Labiatae, Leucosceptrum canum. Their structures including relative stereochemistry were determined by comprehensive 1D and 2D NMR, MS, and in the case of 1 and 10, by single crystal X-ray diffraction analyses. This class of unique plant terpenoids was designated as leucosceptrane sesterterpenoids (=leucosceptroids). The potent antifeedant activity of the most abundant compound, leucosceptroid G (3), and a representative compound, leucosceptroid N (10), against the generalist plant-feeding insect Helicoverpa armigera suggested that they might also be defense compounds of L. canum against insects.

Secondary metabolites from Glycine soja and their growth inhibitory effect against Spodoptera litura.

The wild soybean (Glycine soja Sieb. et Zucc) has been reported to be relatively resistant to insect and pathogenic pests. However, the responsible secondary metabolites in the aerial part of this important plant are largely unknown. From the aerial part of G. soja, 13 compounds were isolated and identified, including seven isoflavonoids (1-7), a cyclitol (8), two sterol derivatives (9 and 10), and three triterpenoids (11-13). Compound 7 is a new isoflavonoid, and compounds 9 and 10 are reported as natural products for the first time. The growth inhibitory activity of 1, 3, 4, and 8 against the larvae of Spodoptera litura was investigated. The most abundant isoflavonoid in the aerial part of G. soja, daidzein (1), which could not be metabolized by S. litura, was found to inhibit the insect larvae growth significantly in 3 days after feeding diets containing the compound. Compounds 3, 4, and 8, which could be partially or completely metabolized, were inactive. Our results suggested that the isoflavonoid daidzein (1) might function as a constitutive defense component in G. soja against insect pests.

Novel polyesterified 3,4-seco-grayanane diterpenoids as antifeedants from Pieris formosa.

Pieris formosa is a poisonous plant to livestock and is used as an insecticide in rural areas of China. Two novel polyesterified 3,4-seco-grayanane diterpenoids, pierisoids A and B (1 and 2), were isolated from its flowers and were identified by spectroscopic analysis and X-ray diffraction. Both compounds showed obvious antifeedant activity against cotton bollworm, indicating their toxic properties, suggesting a defensive role of polyesterified 3,4-seco-grayanane diterpenoids for P. formosa against herbivores.