Functional Characterization and Protein Engineering of a Triterpene 3-/6-/2'-O-Glycosyltransferase Reveal a Conserved Residue Critical for the Regiospecificity.

Engineering the function of triterpene glucosyltransferases (GTs) is challenging due to the large size of the sugar acceptors. In this work, we identified a multifunctional glycosyltransferase AmGT8 catalyzing triterpene 3-/6-/2'-O-glycosylation from the medicinal plant Astragalus membranaceus. To engineer its regiospecificity, a small mutant library was built based on semi-rational design. Variants A394F, A394D, and T131V were found to catalyze specific 6-O, 3-O, and 2'-O glycosylation, respectively. The origin of regioselectivity of AmGT8 and its A394F variant was studied by molecular dynamics and hydrogen deuterium exchange mass spectrometry. Residue 394 is highly conserved as A/G and is critical for the regiospecificity of the C- and O-GTs TcCGT1 and GuGT10/14. Finally, astragalosides III and IV were synthesized by mutants A394F, T131V and P192E. This work reports biocatalysts for saponin synthesis and gives new insights into protein engineering of regioselectivity in plant GTs.

[Effects of Exogenous Phosphorus on Rice Growth and Cadmium Accumulation and Transportation Under Cadmium Stress].

In this study, we investigated the effects of exogenous phosphorus on the accumulation and transportation of cadmium in rice plants through a hydroponic experiment. In the experiment, the rice variety was Huanghuazhan, P solution concentrations were 10.0-45.0 mg ·L-1 that was made using NaH2PO4, and Cd solution concentrations were 0.1 mg ·L-1 and 0.2 mg ·L-1. The results showed that: ① the biomass in all parts of rice plants and contents of photosynthetic pigment (chlorophyll a, chlorophyll b, and carotenoid) increased gradually with an increase in exogenous P. ② Content of Cd in rice stems, leaves, husk, and brown rice increased gradually with an increase in the amounts of exogenous P. The content of Cd in brown rice increased by 2.8%-22.8% and 40.9%-61.8% when treated with Cd concentrations of 0.1 mg ·L-1 and 0.2 mg ·L-1 in hydroponic solutions, respectively. ③ Cd accumulation in rice plants was accelerated due to the application of exogenous P. Cd accumulating amounts increased from 395.1 µg ·plant-1 to 542.6 µg ·plant-1 and 639.6 µg ·plant-1 to 1082.0 µg ·plant-1 when treated with Cd concentrations of 0.1 and 0.2 mg ·L-1 in hydroponic solutions, respectively. ④ With an increase in the applied amounts of exogenous P, the P/Cd quality ratio in rice roots increased, while those in rice stems, leaves, husks, and brown rice decreased; meanwhile, the Cd transfer coefficients from root to stem (TFroot-stem) and stem to leaf (TFstem-leaf) increased. This showed that there was a certain synergistic effect between P and Cd in the rice parts. Finally, the application of exogenous P promoted the transfer of Cd from the rice root to other rice tissues, resulting in a synergistic effect on Cd accumulation and transportation in various rice tissues and increased Cd contents in brown rice.

Effect of ω-3 polyunsaturated fatty acids on liver function and inflammatory reaction in patients undergoing hepatectomy: a systematic review and meta-analysis of randomized control trials.

INTRODUCTION: Several studies have investigated the relationship between ω-3 polyunsaturated fatty acids (PUFAs) administration and liver function and inflammatory reaction in patients undergoing liver resection, but the results remain conflicting and inconclusive. Areas covered: In this meta-analysis, a relevant database search was performed to retrieve all the randomized controlled trials (RCTs) exploring the effect of ω-3 PUFAs administration in patients undergoing hepatectomy until the end of April 2018. A random effect model was used to conduct this meta-analysis with RevMan 5.3.5 software. The quality of evidence for each postoperative outcome was assessed using the GRADEpro analysis. Expert opinion: 4 RCTs including 553 patients (277 with and 276 without ω-3 PUFAs) were identified. ω-3 PUFAs significantly reduced alanine aminotransferase [Mean difference (MD): -68.82, 95% confidence interval (CI): -108.55 to - 29.08; p = 0.0007]; aspartate aminotransferase (MD: -64.92, 95% CI: -112.87 to -16.98; p = 0.008), white blood cell count (MD: -1.22, 95% CI: -2.15 to -0.29; p = 0.01) and increased the level of pre-albumin on postoperative day 3 (MD: 10.42, 95% CI: 4.84 to 15.99; p = 0.0002). The results indicate that ω-3 PUFAs administration has a positive impact on the liver function and inflammatory reaction in patients undergoing liver resection.

Enhanced LL-37 expression following vitamin D supplementation in patients with cirrhosis and spontaneous bacterial peritonitis.

BACKGROUND & AIMS: The morbidity and mortality of spontaneous bacterial peritonitis (SBP) are high among patients with cirrhosis; however, the mechanisms of SBP pathogenesis are poorly understood. This study aimed to determine the role of the vitamin D-LL-37 pathway in the pathogenesis and treatment in patients with cirrhosis and SBP. METHODS: Serum 25-hydroxyvitamin D concentrations of 119 patients with chronic liver diseases were tested. Vitamin D receptor (VDR) and LL-37 in peritoneal leucocytes of cirrhotic and ascitic patients with SBP were detected and compared with those without SBP. Then the peritoneal macrophages of non-infected patients were cultured and activated by lipopolysaccharide (LPS) to analyse the changes of VDR and LL-37 expressions after incubation with vitamin D. RESULTS: Vitamin D deficiency or insufficiency was found in all of patients with cirrhosis. LPS inhibited VDR and LL-37 expression in peritoneal macrophages [1.3-fold decrease (P = 0.003) and 20-fold decrease (P = 0.010) respectively]. However, vitamin D could reverse the inhibition of both VDR and LL-37 [1.5-fold increase (P = 0.001) and 2000-fold increase (P < 0.001) respectively]. The effect of the incubation time following vitamin D supplementation was significant for LL-37 expression, with a peak expression found at 36 h (P < 0.001). CONCLUSIONS: When vitamin D levels were low, bacteria inhibited VDR and LL-37 responses in peritoneal macrophages as a mechanism to evade antibacterial defence. Vitamin D supplementation could up-regulate peritoneal macrophage VDR and LL-37 expressions, which resulted in an enhanced immunological defence against SBP in patients with cirrhosis and ascites.

Inhibition of chronic pancreatitis and pancreatic intraepithelial neoplasia (PanIN) by capsaicin in LSL-KrasG12D/Pdx1-Cre mice.

Capsaicin is a major biologically active ingredient of chili peppers. Extensive studies indicate that capsaicin is a cancer-suppressing agent via blocking the activities of several signal transduction pathways including nuclear factor-kappaB, activator protein-1 and signal transducer and activator of transcription 3. However, there is little study on the effect of capsaicin on pancreatic carcinogenesis. In the present study, the effect of capsaicin on pancreatitis and pancreatic intraepithelial neoplasia (PanIN) was determined in a mutant Kras-driven and caerulein-induced pancreatitis-associated carcinogenesis in LSL-Kras(G12D)/Pdx1-Cre mice. Forty-five LSL-Kras(G12D)/Pdx1-Cre mice and 10 wild-type mice were subjected to one dose of caerulein (250 µg/kg body wt, intraperitoneally) at age 4 weeks to induce and synchronize the development of chronic pancreatitis and PanIN lesions. One week after caerulein induction, animals were randomly distributed into three groups and fed with either AIN-76A diet, AIN-76A diet containing 10 p.p.m. capsaicin or 20 p.p.m. capsaicin for a total of 8 weeks. The results showed that capsaicin significantly reduced the severity of chronic pancreatitis, as determined by evaluating the loss of acini, inflammatory cell infiltration and stromal fibrosis. PanIN formation was frequently observed in the LSL-Kras(G12D)/Pdx1-Cre mice. The progression of PanIN-1 to high-grade PanIN-2 and -3 were significantly inhibited by capsaicin. Further immunochemical studies revealed that treatment with 10 and 20 p.p.m. capsaicin significantly reduced proliferating cell nuclear antigen-labeled cell proliferation and suppressed phosphorylation of extracellular signal-regulated kinase (ERK) and c-Jun as well blocked Hedgehog/GLI pathway activation. These results indicate that capsaicin could be a promising agent for the chemoprevention of pancreatic carcinogenesis, possibly via inhibiting pancreatitis and mutant Kras-led ERK activation.