Tyroserleutide tripeptide affects calcium homeostasis of human hepatocarcinoma BEL-7402 cells

This study aimed to observe the effects of tyroserleutide (tyrosyl-seryl-leucine, YSL) on the growth of human hepatocarcinoma BEL-7402 that was transplanted into nude mice, and explore its anti-tumor mechanism preliminarily. YSL, at doses of 80 μg-kg^-1 · d^-1, 160 μg·kg^-1 ·d^-1 and 320 μg · kg^-1 · d^-1 significantly inhibited the growth of the human hepatocarcinoma BEL-7402 tumor in nude mice, producing inhibition of 21.66%, 41.34%, and 34.78%, respectively. Ultra structure of BEL-7402 tumor in nude mice showed that YSL could induce tumor cells apoptosis and necrosis, cell organelle mitochondria and endoplasmic reticulum damage, and calcium overload. By confocal laser scanning microscopy and flow cytometry, we found that 10 μg/mL YSL rapidly induced an increase of the concentration of cytoplasmic free calcium in BEL-7402 cells in vitro, and maintained high concentrations of cytoplasmic free calcium for 1 h. Then the calcium concentration began to decrease after 2 h, and was lower than that of the control group at 4 h and 24 h (P< 0.05). YSL also decreased the mitochondrial transmembrane potential of BEL-7402 cells in vitro, but had no effect on the calcium homeostasis or mitochondrial transmembrane potential of Chang liver hepatocytes. So affecting calcium homeostasis, then inducing apoptosis and necrosis may be a mechanism by which YSL inhibits the tumor growth in animal model.     

EPR characterization of oxide supported transition metal ions: Relevance to catalysis

EPR spectroscopy is a powerful tool to identify at a molecular level, the different steps of catalyst preparation, and of catalytic reactions:

1. Deposition of paramagnetic transition metal ions onto a support is monitored, and the coordination sphere of the metallic center is characterized by EPR.
2. The catalyst is also characterized after activation (thermal oxidation or reduction):

- the distribution among the different sites in zeolites can be determined;

- the dispersion of the active phase may be appreciated;

- the unsaturation degree of the active site may be evaluated using probe molecules such as water or¹³C enriched carbon monoxide.

1. The catalytic mechanisms can be investigated by studying the elementary steps of the catalytic reaction, as illustrated for methanol oxidation over Mo/SiO₂ catalysts whose EPR results have extended the reaction mechanism proposed on the basis of kinetic data. In addition, reaction intermediates may be isolated inquasi-in situ conditions as in the case of olefin oligomerization catalyzed by Ni/SiO₂ systems.

     

Correlations between glycolysis with clinical traits and immune function in bladder urothelial carcinoma

Background: Glycolysis was a representative hallmark in the tumor microenvironment (TME), and we aimed to explore the correlations between glycolysis with immune activity and clinical traits in bladder urothelial carcinoma (BLCA).Methods: Our study obtained glycolysis scores for each BLCA samples from TCGA by a single-sample gene set enrichment analysis (ssGSEA) algorithm, based on a glycolytic gene set. The relationship between glycolysis with prognosis, clinical characteristics, and immune function were investigated subsequently.Results: We found that enhanced glycolysis was associated with poor prognosis and metastasis in BLCA. Moreover, glycolysis had a close correlation with immune function, and enhanced glycolysis increased immune activities. In other words, glycolysis had a positive correlation with immune activities. Immune checkpoints such as IDO1, CD274, were up-regulated in high-glycolysis group as well.Conclusion: We speculated that in BLCA, elevated glycolysis enhanced immune function, which caused tumor cells to overexpress immune checkpoints to evade immune surveillance. Inhibition of glycolysis might be a promising assistant for immunotherapy in bladder cancer.     

Effect of chitosan‐alginate nanoparticles and ultrasound on the efficiency of gene transfection of human cancer cells

Background

Gene therapy has been used to treat a variety of health problems, but transfection inefficiency and the lack of safe vectors have limited clinical progress. Fabrication of a vector that is safe and has high transfection efficiency is crucial for the development of successful gene therapy. The present study aimed to synthesize chitosan‐alginate nanoparticles that can be used as carriers of the pAcGFP1‐C1 plasmid and to use these nanoparticles with an ultrasound protocol to achieve high efficiency gene transfection.

Methods

Chitosan was complexed with alginate and the pAcGFP1‐C1 plasmid at different charge ratios to create chitosan‐alginate‐DNA nanoparticles (CADNs). The average particle size and loading efficiency were measured. Plasmid DNA retardation and integrity were analysed on 1% agarose gels. The effect of CADNs and ultrasound on the efficiency of transfection of cells and subcutaneous tumors was evaluated.

Results

In the CADNs, the average size of incorporated plasmid DNA was 600–650 nm and the loading efficiency was greater than 90%. On the basis of the results of the plasmid DNA protection test, CADNs could protect the transgene from DNase I degradation. The transgene product expression could be enhanced efficiently if cells or tumor tissues were first given CADNs and then treated with ultrasound.

Conclusions

The use of CADNs combined with an ultrasound regimen is a promising method for safe and effective gene therapy. Copyright © 2009 John Wiley & Sons, Ltd.

     

The auxin-inducible phosphate transporter AsPT5 mediates phosphate transport and is indispensable for arbuscule formation in Chinese milk vetch at moderately high phosphate supply

Phosphorus is a macronutrient that is essential for plant survival. Most land plants have evolved the ability to form a mutualistic symbiosis with arbuscular mycorrhizal (AM) fungi, which enhances phosphate (Pi) acquisition. Modulation of Pi transporter systems is the master strategy used by mycorrhizal plants to adapt to ambient Pi concentrations. However, the specific functions of PHOSPHATE TRANSPORTER 1 (PHT1) genes, which are Pi transporters that are responsive to high Pi availability, are largely unknown. Here, we report that AsPT5, an Astragalus sinicus (Chinese milk vetch) member of the PHT1 gene family, is conserved across dicotyledons and is constitutively expressed in a broad range of tissues independently of Pi supply, but is remarkably induced by indole-3-acetic acid (auxin) treatment under moderately high Pi conditions. Subcellular localization experiments indicated that AsPT5 localizes to the plasma membrane of plant cells. Using reverse genetics, we showed that AsPT5 not only mediates Pi transport and remodels root system architecture but is also essential for arbuscule formation in A. sinicus under moderately high Pi concentrations. Overall, our study provides insight into the function of AsPT5 in Pi transport, AM development and the cross-talk between Pi nutrition and auxin signalling in mycorrhizal plants.     

Actinopolyspora dayingensis sp. nov., a novel halophilic actinomycete isolated from a hypersaline lake

A novel halophilic, filamentous actinomycete, designated TRM 4064^T, was isolated from a hypersaline habitat in Sichuan Province, China. Phylogenetic analysis based on an almost-complete 16S rRNA gene sequence of strain TRM 4064^T showed that it was most closely related to Actinopolyspora mortivallis (99.1 % sequence similarity). The sequence similarities between strain TRM 4064^T and other Actinopolyspora species with validly-published names were <97.0 %. However, it had relatively low mean values for DNA–DNA relatedness with the A. mortivallis DSM 44261^T (23.2 %). Optimal growth occurred at 37 °C, pH 7.0 and in the presence of 13 % (w/v) NaCl. The whole-cell sugar pattern consists of xylose, glucose, ribose and arabinose. The predominant menaquinones are MK-10(H₄) (38.2 %), MK-9(H₄) (25.1 %), MK-9(H₂) (28.6 %) and MK-8(H₄) (7.3 %). The major fatty acids are anteiso-C_17:0 (36.9 %) and iso-C_17:0 (19.3 %). The diagnostic phospholipids detected were diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylcholine (PC), phosphatidylinositol (PI) and two unknown phospholipids. The G+C content of the genomic DNA of the type strain is 66.3 mol%. Strain TRM 4064^T therefore represents a novel species of the genus Actinopolyspora, for which the name Actinopolyspora dayingensis sp. nov. is proposed. The type strain is TRM 4064^T (= KCTC 19979^T = CCTCC AA 2010010^T).     

Peony Glycosides Protect Against Corticosterone-Induced Neurotoxicity in PC12 Cells

Preclinical and clinical investigations have shown the involvement of dysregulation of hypothalamic–pituitary–adrenal (HPA) axis in the pathogenesis of depression. Hypercortisolemia and the associated hippocampal atrophy were observed in patients with depression, which could be ameliorated by the treatment with antidepressants. Therefore, neuroprotection has been proposed to be one of the acting mechanisms of antidepressant. Previous studies in our laboratory have demonstrated the antidepressant-like activity of total glycosides of peony (TGP) in mice. This study aimed to examine the effect of TGP treatment on corticosterone-induced neurotoxicity in cultured rat pheochromocytoma (PC12) cells. Treating the cells with corticosterone at 200 μM for 48 h caused apoptotic cell death. The cytotoxicity was associated with the activation of caspase-3 activity and the decrease in the mRNA ratio of bcl-2 to bax. TPG treatment at increasing doses (1–10 mg/l) protected against the corticosterone-induced toxicity in PC12 cells in a dose-dependent manner. The cytoprotection afforded by TGP treatment was associated with the inhibition of caspase-3 activity and the up-regulation of bcl-2/bax mRNA ratio. The anti-apoptotic effect of TGP is therefore likely mediated by the suppression of the mitochondrial pathway leading to apoptosis.     

Ubc9 acetylation modulates distinct SUMO target modification and hypoxia response

While numerous small ubiquitin‐like modifier (SUMO) conjugated substrates have been identified, very little is known about the cellular signalling mechanisms that differentially regulate substrate sumoylation. Here, we show that acetylation of SUMO E2 conjugase Ubc9 selectively downregulates the sumoylation of substrates with negatively charged amino acid‐dependent sumoylation motif (NDSM) consisting of clustered acidic residues located downstream from the core ψ‐K‐X‐E/D consensus motif, such as CBP and Elk‐1, but not substrates with core ψ‐K‐X‐E/D motif alone or SUMO‐interacting motif. Ubc9 is acetylated at residue K65 and K65 acetylation attenuates Ubc9 binding to NDSM substrates, causing a reduction in NDSM substrate sumoylation. Furthermore, Ubc9 K65 acetylation can be downregulated by hypoxia via SIRT1, and is correlated with hypoxia‐elicited modulation of sumoylation and target gene expression of CBP and Elk‐1 and cell survival. Our data suggest that Ubc9 acetylation/deacetylation serves as a dynamic switch for NDSM substrate sumoylation and we report a previously undescribed SIRT1/Ubc9 regulatory axis in the modulation of protein sumoylation and the hypoxia response.     

The role of disulfide bond isomerase A (DsbA) of Escherichia coli O157:H7 in biofilm formation and virulence

The role of periplasmic disulfide oxidoreductase DsbA in Shiga toxin-producing Escherichia coli O157:H7 (STEC) was investigated. Deletion of dsbA (DeltadsbA) significantly decreased cell motility and alkaline phosphatase activity in STEC. STEC DeltadsbA also showed greater sensitivity to menadione and under low pH conditions. Significant reductions in surface attachment to both biotic (HT-29 epithelial cells) and abiotic (polystyrene and polyvinyl chloride) surfaces were observed in STEC DeltadsbA. In addition, no biofilm formation was detected in STEC DeltadsbA compared to wild-type cells in glass capillary tubes under continuous flow-culture system conditions. In the nematode model Caenorhabditis elegans-killing assay, the deletion of dsbA in STEC resulted in attenuated virulence compared to wild-type cells. STEC DeltadsbA was also found to have a reduced ability to colonize the nematode gut. These results suggest that DsbA plays important roles in biofilm formation and virulence in STEC cells.