Schisantherin A ameliorates liver fibrosis through TGF-ß1mediated activation of TAK1/MAPK and NF-κB pathways in vitro and in vivo.

BACKGROUD: Schisandra chinensis, a traditional Chinese medicine for liver protection, can significantly improve liver fibrosis. However, it is still unclear which active components in Schisandra chinensis play an anti-fibrosis role. PURPOSE: The purpose of present study was to observe the anti-fibrosis effect of schisantherin A (SCA) on liver fibrosis and explore its underlying mechanism. METHODS: The liver fibrosis model of mice was constructed by the progressive intraperitoneal injection of thioacetamide (TAA), and SCA (1, 2, and 4 mg/kg) was administered by gavage for 5 weeks. The biochemical indicators and inflammatory cytokines were measured, changes in the pathology of the mice liver were observed by hematoxylin & eosin (H&E) and Masson stainings for studying the anti-fibrosis effect of SCA. A hepatic stellate cell (HSCs) activation model induced by transforming growth factor-ß1 (TGF-ß1) was established, and the effect of SCA on the HSCs proliferation was observed by MTT assay. The expressions of target proteins related to transforming growth factor-ß-activated kinase 1 (TAK1)/mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) pathways were evaluated by western blotting, immunohistochemistry or immunofluorescence analysis, to explore the potential mechanism of SCA. RESULTS: SCA could significantly ameliorate the pathological changes of liver tissue induced by TAA, and reduce the serum transaminase level, the hydroxyproline level and the expression of α-smooth muscle actin (α-SMA) and collagen 1A1 (COL1A1) proteins in the liver tissue. SCA could significantly lower the levels of tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß) and interleukin-6 (IL-6) in the serum and liver tissue, and down-regulate the expression of target proteins related to TAK1/MAPK and NF-κB pathways in the liver tissue. The in vitro studies demonstrated that SCA significantly inhibited the proliferation and activation of HCS-T6 cells induced by TGF-ß1, decreased TNF-α and IL-6 levels, and inhibited the TAK1 activation induced by TGF-ß1 and then the expression of MAPK and NF-κB signaling pathway-related proteins. CONCLUSION: Together, SCA can ameliorate the liver fibrosis induced by TAA and the HSC-T6 cell activation induced by TGF-ß1 in mice, and its mechanism may be to inhibit the HSCs activation and inflammatory response by inhibiting TGF-ß1 mediated TAK1/MAPK and signal pathways.

Schisandra chinensis acidic polysaccharide partialy reverses acetaminophen-induced liver injury in mice.

Schisandra chinensis is a hepatoprotective herb that has been used for centuries in China. Polysaccharide is one of the major active components in S. chinensis, which has been reported to improve liver injuries induced by carbon tetrachloride, alcohol, or high-fat diet. In this study, we observed the effects and corresponding mechanisms of the secondary component of Schisandra polysaccharide (acidic polysaccharide, SCAP) on a murine model of severe acute liver injury induced by acetaminophen (APAP). SCAP significantly decreased the serum alanine aminotransferase (ALT), aspartate aminotransferas (AST), tumor necrosis factor-α (TNF-α), and interleukin-1ß (IL-1ß) levels, and was found to alleviate hepatic pathological alterations in the mouse model. Meanwhile, SCAP revealed a protective effects on the liver injury-related enzymes and factors, such as significantly diminished malondialdehyde (MDA) levels and glutathione (GSH) depletion, reduced ratio of B-cell lymphoma-2 (Bcl-2)-associated X protein (Bax)/Bcl-2, prohibited cleaved caspase-3 expression, and elevated the expression of p-AMPK, p-Akt, p-glycogen synthase kinase 3ß (GSK 3ß), nuclear factor erythroid 2-derived-like 2 (Nrf 2) and heme oxygenase-1 (HO-1) proteins in the liver tissues of the mouse model. In conclusion, we speculated that the protective activities of SCAP on the APAP-induced mouse model of acute liver injury might be related to its antioxidation, anti-inflammation and anti-apoptosis properties.

Hypoglycemic Effect of Acidic Polysaccharide from Schisandra chinensis on T2D Rats Induced by High-Fat Diet Combined with STZ.

Polysaccharide is a key bioactive component of Schisandra chinensis and has significant pharmacological activities. The aim of this study was to evaluate the anti-diabetic effect of acidic polysaccharide from Schisandra chinensis (SCAP). Type 2 diabetic (T2D) rats were developed by giving a high-fat diet (HFD) combined with low-dose streptozotocin (STZ), and administered orally with SCAP (25, 50 mg/kg) for 8 weeks. Fasting blood glucose (FBG), fasting insulin (FINS), triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), malondialdehyde (MDA), and superoxide dismutase (SOD) in the rat's serum were measured. Oral glucose tolerance test (OGTT) and pathological changes of pancreas were observed. Furthermore, expressions of c-Jun N-terminal kinase (JNK), B-cell lymphoma 2-associated X protein (BAX), B-cell lymphoma 2 (Bcl-2), and Cleaved Caspase-3 in pancreatic islet were detected. The results showed that SCAP decreased FBG, TG, TC, LDL-C and MDA levels, increased insulin, HDL-C levels and SOD activity, improved the pathological changes in pancreatic islet. Furthermore, SCAP inhibited the up-regulation of phosphorylated JNK, BAX and Cleaved Caspase-3 proteins, and increased Bcl-2 protein expression. These data indicate that SCAP has a therapeutic effect in T2D rats, and the mechanism may be related to its protection against ß-cells apoptosis by regulating apoptosis-related proteins expression to alleviate the injury caused by the oxidative stress.

XA23 is an executor R protein and confers broad-spectrum disease resistance in rice.

The majority of plant disease resistance (R) genes encode proteins that share common structural features. However, the transcription activator-like effector (TALE)-associated executor type R genes show no considerable sequence homology to any known R genes. We adopted a map-based cloning approach and TALE-based technology to isolate and characterize Xa23, a new executor R gene derived from wild rice (Oryza rufipogon) that confers an extremely broad spectrum of resistance to bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo). Xa23 encodes a 113 amino acid protein that shares 50% identity with the known executor R protein XA10. The predicted transmembrane helices in XA23 also overlap with those of XA10. Unlike Xa10, however, Xa23 transcription is specifically activated by AvrXa23, a TALE present in all examined Xoo field isolates. Moreover, the susceptible xa23 allele has an identical open reading frame of Xa23 but differs in promoter region by lacking the TALE binding element (EBE) for AvrXa23. XA23 can trigger a strong hypersensitive response in rice, tobacco, and tomato. Our results provide the first evidence that plant genomes have an executor R gene family of which members execute their function and spectrum of disease resistance by recognizing the cognate TALEs in the pathogen.

XA23 is an executor R protein and confers broad-spectrum disease resistance in rice.

The majority of plant disease resistance (R) genes encode proteins that share common structural features. However, the transcription activator-like effector (TALE) associated executor type R genes show no considerable sequence homology to any known R genes. We adopted a map-based cloning approach and TALE-based technology to isolate and characterize Xa23, a new executor R gene derived from the wild rice (Oryza rufipogon) that confers an extremely broad spectrum of resistance to bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo). Xa23 encodes a 113-amino acid protein that shares 50% identity to the known executor R protein XA10. The predicted transmembrane helices in XA23 also overlap with those of XA10. Unlike Xa10, however, Xa23 transcription is specifically activated by AvrXa23, a TALE present in all examined Xoo field isolates. Moreover, the susceptible xa23 allele has an identical open reading frame of Xa23, but differs in promoter region by lacking the TALE binding-element (EBE) for AvrXa23. XA23 can trigger strong hypersensitive response in rice, tobacco and tomato. Our results provide the first evidence that plant genomes have an executor R gene family in which members execute their function and spectrum of disease resistance by recognizing the cognate TALEs in pathogen.

The broad bacterial blight resistance of rice line CBB23 is triggered by a novel transcription activator-like (TAL) effector of Xanthomonas oryzae pv. oryzae.

Bacterial blight (BB), caused by Xanthomonas oryzae pv. oryzae (Xoo), is not only a disease devastating rice production worldwide, but also an ideal model system for the study of the interaction between plants and their bacterial pathogens. The rice near-isogenic line (NIL) CBB23, derived from a cross between a wild rice Oryza rufipogon accession (RBB16) and a susceptible indica rice variety (Jingang 30), is highly resistant to all field Xoo strains tested so far. Although the BB resistance of CBB23 has been widely used in rice breeding programmes, the mechanism of its extremely broad-spectrum resistance remains unknown. Here, we report the molecular cloning of an avirulence gene, designated as avrXa23, from Xoo strain PXO99(A) . We validate that AvrXa23, a novel transcription activator-like effector, specifically triggers the broad-spectrum BB resistance in CBB23. The prevalence of avrXa23 in all 38 Xoo strains surveyed may explain the broad-spectrum feature of BB resistance in CBB23. The results will significantly facilitate the molecular cloning of the corresponding resistance (R) gene in the host, and provide new insights into our understanding of the molecular mechanism for broad-spectrum disease resistance in plants.