Inhibition of Filamin-A Reduces Cancer Metastatic Potential

Filamin-A cross-links actin filaments into dynamic orthogonal networks, and interacts with an array of proteins of diverse cellular functions. Because several filamin-A interaction partners are implicated in signaling of cell mobility regulation, we tested the hypothesis that filamin-A plays a role in cancer metastasis. Using four pairs of filamin-A proficient and deficient isogenic cell lines, we found that filamin-A deficiency in cancer cells significantly reduces their migration and invasion. Using a xenograft tumor model with subcutaneous and intracardiac injections of tumor cells, we found that the filamin-A deficiency causes significant reduction of lung, splenic and systemic metastasis in nude mice. We evaluated the expression of filamin-A in breast cancer tissues by immunohistochemical staining, and found that low levels of filamin-A expression in cancer cells of the tumor tissues are associated with a better distant metastasis-free survival than those with normal levels of filamin-A. These data not only validate filamin-A as a prognostic marker for cancer metastasis, but also suggest that inhibition of filamin-A in cancer cells may reduce metastasis and that filamin-A can be used as a therapeutic target for filamin-A positive cancer.     

橡胶草及其同域近缘种表型多样性研究

对蒲公英属橡胶草及其同域10个近缘种共13份材料的59个表型性状(数量性状24个,质量性状35个)进行了观测,通过方差分析、因子分析和聚类分析对其形态性状多样性和种间亲缘关系进行研究,以明确各表型性状对种质分类的重要性及其贡献,为橡胶草品种选育及蒲公英属植物的分类和种质资源保存利用提供依据。结果显示:(1)13份蒲公英属种质资源在数量性状上变异系数在7.50%~55.00%之间,平均为28.25%,多样性指数在1.157~2.032之间,平均为1.663,具有丰富的表型多样性。(2)质量性状方面,变异系数的变化范围在20.40%~67.44%之间,多样性指数变化范围在0.271~1.672之间,平均为1.136,总体上是数量性状形态多样性指数大于质量性状。(3)59个性状的主成分分析中前7个主成分的累计贡献率为84.767%,花部形态变异是蒲公英属植物表型分化的主要因素。(4)利用欧氏距离进行的Ward’s聚类分析结果表明,13份材料可分为4大类群,同一地区的大部分种聚在一起,呈现出一定的地域性,亲缘关系较近;但来源于3个居群的橡胶草却被划分在2个类群中,表现出较远的亲缘关系。研究表明,蒲公英属植物种质材料具有丰富的质量和数量性状变异,表型多样性丰富。     

Combinatorial signals of activin/nodal and bone morphogenic protein regulate the early lineage segregation of human embryonic stem cells

Cell fate commitment of pre-implantation blastocysts, to either the inner cell mass or trophoblast, is the first step in cell lineage segregation of the developing human embryo. However, the intercellular signals that control fate determination of these cells remain obscure. Human embryonic stem cells (hESCs) provide a unique model for studying human early embryonic development. We have previously shown that Activin/Nodal signaling contributes to maintaining pluripotency of hESCs, which are derivatives of the inner cell mass. Here we further demonstrate that the inhibition of Activin/Nodal signaling results in the loss of hESC pluripotency and trophoblast differentiation, similar to BMP4-induced trophoblast differentiation from hESCs. We also show that the trophoblast induction effect of BMP4 correlates with and depends on the inhibition of Activin/Nodal signaling. However, the activation of BMP signaling is still required for trophoblast differentiation when Activin/Nodal signaling is inhibited. These data reveal that the early lineage segregation of hESCs is determined by the combinatorial signals of Activin/Nodal and BMP.     

Trans‐3,5,4´‐trimethoxystilbene reduced gefitinib resistance in NSCLCs via suppressing MAPK/Akt/Bcl‐2 pathway by upregulation of miR‐345 and miR‐498

Despite initial dramatic efficacy of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (EGFR‐TKIs) in EGFR‐mutant lung cancer patients, subsequent emergence of acquired resistance is almost inevitable. Resveratrol and its derivatives have been found to exert some effects on EGFR‐TKI resistance in non‐small cell lung cancer (NSCLC), but the underlying mechanisms remain unclear. We screened several NSCLC cell lines with gefitinib resistance by MTT assay and analysed the miR‐345/miR‐498 expression levels. NSCLC cells were pre‐treated with a resveratrol derivative, trans‐3,5,4‐trimethoxystilbene (TMS) and subsequently challenged with gefitinib treatment. The changes in apoptosis and miR‐345/miR‐498 expression were analysed by flow cytometry and q‐PCR respectively. The functions of miR‐345/miR‐498 were verified by CCK‐8 assay, cell cycle analysis, dual‐luciferase reporter gene assay and immunoblotting analysis. Our results showed that the expression of miR‐345 and miR‐498 significantly decreased in gefitinib resistant NSCLC cells. TMS pre‐treatment significantly upregulated the expression of miR‐345 and miR‐498 increasing the sensitivity of NSCLC cells to gefitinib and inducing apoptosis. MiR‐345 and miR‐498 were verified to inhibit proliferation by cell cycle arrest and regulate the MAPK/c‐Fos and AKT/Bcl‐2 signalling pathways by directly targeting MAPK1 and PIK3R1 respectively. The combination of TMS and gefitinib promoted apoptosis also by miR‐345 and miR‐498 targeting the MAPK/c‐Fos and AKT/Bcl‐2 signalling pathways. Our study demonstrated that TMS reduced gefitinib resistance in NSCLCs via suppression of the MAPK/Akt/Bcl‐2 pathway by upregulation of miR‐345/498. These findings would lay the theoretical basis for the future study of TMS for the treatment of EGFR‐TKI resistance in NSCLCs.     

Equilibrium analysis and phase synchronization of two coupled HR neurons with gap junction

The properties of equilibria and phase synchronization involving burst synchronization and spike synchronization of two electrically coupled HR neurons are studied in this paper. The findings reveal that in the non-delayed system the existence of equilibria can be turned into intersection of two odd functions, and two types of equilibria with symmetry and non-symmetry can be found. With the stability and bifurcation analysis, the bifurcations of equilibria are investigated. For the delayed system, the equilibria remain unchanged. However, the Hopf bifurcation point is drastically affected by time delay. For the phase synchronization, we focus on the synchronization transition from burst synchronization to spike synchronization in the non-delayed system and the effect of coupling strength and time delay on spike synchronization in delayed system. In addition, corresponding firing rhythms and spike synchronized regions are obtained in the two parameters plane. The results allow us to better understand the properties of equilibria, multi-time-scale properties of synchronization and temporal encoding scheme in neuronal systems.     

Analysis of synonymous codon usage in H5N1 virus and other influenza A viruses

In this study, we calculated the codon usage bias in H5N1 virus and performed a comparative analysis of synonymous codon usage patterns in H5N1 virus, five other evolutionary related influenza A viruses and a influenza B virus. Codon usage bias in H5N1 genome is a little slight, which is mainly determined by the base compositions on the third codon position. By comparing synonymous codon usage patterns in different viruses, we observed that the codon usage pattern of H5N1 virus is similar with other influenza A viruses, but not influenza B virus, and the synonymous codon usage in influenza A virus genes is phylogenetically conservative, but not strain-specific. Synonymous codon usage in genes encoded by different influenza A viruses is genus conservative. Compositional constraints could explain most of the variation of synonymous codon usage among these virus genes, while gene function is also correlated to synonymous codon usages to a certain extent. However, translational selection and gene length have no effect on the variations of synonymous codon usage in these virus genes.     

巴氏杆菌糖酵解酶的黏附作用研究

巴氏杆菌（主要是多杀性巴氏杆菌）可以引起多种动物疫病（巴氏杆菌病）,同时也引起人类感染发病。[目的] 研究巴氏杆菌糖酵解酶对宿主细胞（兔肾细胞）和两种常见分子[纤连蛋白（fibronectin,Fn）和血浆纤维蛋白溶解酶原（plasminogen,Plg）]的黏附作用。[方法] 采用原核表达系统对多杀性巴氏杆菌的糖酵解酶进行表达并纯化及制备多克隆抗体,通过菌体表面蛋白定位检测、黏附与黏附抑制等实验探究巴氏杆菌糖酵解酶的黏附作用。[结果] 菌体表面蛋白检测结果显示除烯醇化酶和丙酮酸激酶外的7个糖酵解酶在多杀性巴氏杆菌表面存在。这7个糖酵解酶均能黏附兔肾细胞,但仅有磷酸葡萄糖异构酶的多克隆抗体能对多杀性巴氏杆菌黏附宿主细胞产生抑制作用。Far Western blotting结果显示9个糖酵解酶均能结合宿主Fn和Plg。招募抑制实验结果显示磷酸葡萄糖异构酶、醛缩酶、磷酸甘油酸变位酶的抗体对多杀性巴氏杆菌结合Fn和Plg都有抑制作用,磷酸果糖激酶、丙糖磷酸异构酶、甘油醛-3-磷酸脱氢酶、磷酸甘油激酶抗体仅对多杀性巴氏杆菌结合Fn或Plg有抑制作用。[结论] 多杀性巴氏杆菌糖酵解酶成员葡萄糖异构酶、磷酸果糖激酶、醛缩酶、丙糖磷酸异构酶、甘油醛-3-磷酸脱氢酶、磷酸甘油激酶、磷酸甘油酸变位酶在多杀性巴氏杆菌黏附宿主细胞或分子过程中发挥作用。该研究的完成将加深巴氏杆菌病分子发病机制的认识,并为巴氏杆菌病的诊断标识筛选、新型疫苗创制和药物靶标筛选等提供基础数据。     

DNA barcoding of Gaultheria L.in China (Ericaceae: Vaccinioideae)

Four DNA barcoding loci,chloroplast loci rbcL,matK,trnH-psbA,and nuclear locus internal transcribed spacer (ITS),were tested for the accurate discrimination of the Chinese species of Gaultheria by using intraspecific and interspecific pairwise P-distance,Wilcoxon signed rank test,and tree-based analyses.This study included 186 individuals from 89 populations representing 30 species.For all individuals,single locus markers showed high levels of sequencing universality but were ineffective for species resolvability.Polymerase chain reaction amplification and sequencing were successful for all four loci.Both ITS and matK showed significantly higher levels of interspecific species delimitation than rbcL and trnH-psbA.A combination ofmatK and ITS was the most efficient DNA barcode among all studied regions,however,they do not represent an appropriate candidate barcode for Chinese Gaultheria,by which only 11 out of 30 species can be separated.Loci rbcL,matK,and trnH-psbA,which were recently proposed as universal plant barcodes,have a very poor capacity for species separation for Chinese Gaultheria.DNA barcodes may be reliable tools to identify the evolutionary units of this group,so further studies are needed to develop more efficient DNA barcodes for Gaultheria and other genera with complicated evolutionary histories.     

Signalling events mediating the activation of protein kinase C by interleukin-2 in cytotoxic T cells.

Interleukin-2 (IL-2) plays a vital role in the generation and regulation of the immune response, including important aspects of T cell survival. IL-2-mediated survival of T cells appears to be dependent on the activation of a pool of membrane-associated protein kinase C (PKC) that occurs in the absence of detectable translocation of the enzyme from the cytosol to membranes. In this report we investigate the mechanism(s) responsible for this PKC activation after IL-2 stimulation in the cytotoxic T cell line, CTLL-2. Tyrosine kinase activity, activated after IL-2 stimulation, was found not to be linked to the activation of PKC by the cytokine. On the other hand, a pertussis toxin (PTX)-sensitive G protein did appear coupled to PKC activation since PTX effectively blocked IL-2 stimulated PKC activity. Diacylglycerols (DAG), but not inositol 1,3,5-triphosphate (IP3) and intracellular Ca2+, increased after IL-2 stimulation suggesting that DAGs were generated via the phosphatidylcholine-phospholipase C (PC-PLC) or phosphatidylcholine-phospholipase D (PC-PLD) pathways. The increase in DAG by IL-2 was probably necessary for activation of membrane-resident PKC since exogenously applied DAG stimulated this PKC pool in both intact cells and in isolated membranes. IL-2 also increased arachidonic acid (AA) production in CTLL-2 cells, probably via phospholipase A2 (PLA2) since the PLA2 inhibitors oleoyloxyethyl phosphocholine and AACOCF3 (AACF) effectively blocked IL-2 stimulated PKC activation. Exogenous AA also increased PKC activity in intact cells and isolated membranes, suggesting that AA produced by IL-2 receptor stimulation was probably linked to PKC activation. These results suggest that the activation of membrane-resident PKC by IL-2 involves multiple second messengers, including G proteins, DAG and AA.     

Selective antibacterial activity of the cationic peptide PaDBS1R6 against Gram-negative bacteria

Infections caused by Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa foremost among them, constitute a major worldwide health problem. Bioinformatics methodologies are being used to rationally design new antimicrobial peptides, a potential alternative for treating these infections. One of the algorithms used to develop antimicrobial peptides is the Joker, which was used to design the peptide PaDBS1R6. This study evaluates the antibacterial activities of PaDBS1R6 in vitro and in vivo, characterizes the peptide interaction to target membranes, and investigates the PaDBS1R6 structure in contact with mimetic vesicles. Moreover, we demonstrate that PaDBS1R6 exhibits selective antimicrobial activity against Gram-negative bacteria. In the presence of negatively charged and zwitterionic lipids the structural arrangement of PaDBS1R6 transits from random coil to α-helix, as characterized by circular dichroism. The tertiary structure of PaDBS1R6 was determined by NMR in zwitterionic dodecylphosphocholine (DPC) micelles. In conclusion, PaDBS1R6 is a candidate for the treatment of nosocomial infections caused by Gram-negative bacteria, as template for producing other antimicrobial agents.