大肠杆菌中高效表达rhBMP-4的探讨及初步活性测定

目的 在大肠杆菌中表达具有生物活性的rhBMP-4。方法 在不改变氨基酸序列的前提下,以全基因合成的方式对人BMP-4成熟肽基因全长进行定点突变,将之重组入pET-3c表达载体并转化至大肠杆菌BL21(DE)plysS。IPTG诱导和包涵体复性后,利用C2C12细胞横向成骨细胞分化实验以及小鼠肌袋异位骨形成实验检测其活性。 结果 获得0.348 kb的BMP-4 DNA序列,表达的目的蛋白主要以包涵体的形式存在。经纯化及复性后,体内与体外的活性检测表明rhBMP-4有良好的诱骨生成活性。结论 该方案能够实现rhBMP-4在大肠杆菌中的高效表达。     

Activity of organophosphorus insecticides in bacterial tests for mutagenicity and DNA repair — Direct alkylation vs. metabolic activation and breakdown. I. Butonate,vinylbutonate, trichlorfon,dichlorvos, demethyl dichlorvos and demethyl vinylbutonate

The following organophosphates were tested for their ability to induce DNA damage in a rec-type repair test with Proteus mirabilis strains PG713 (rec^? hcr^?) and PG273 (wild type) and point mutations in his^? strain TA100 of Salmonella typhimurium — butonate: O,O-dimethyl-(1-n-butyryloxy-2,2,2-trichloroethyl)-phosphonate; vinylbutonate: O,O-dimethyl-(n-butyryloxy-2,2-dichlorovinyl)-phosphonate; trichlorfon: O,O-dimethyl-(1-hydroxy-2,2,2-trichloroethyl)-phosphonate; dichlorvos: O,O-dimethyl-O-(2,2-dichlorovinyl)-phosphate; the demethylated derivatives — demethyldichlorvos: O-methyl-O-(2,2-dichlorovinyl)-phosphoric acid; demethyl vinylbutonate: O-methyl-(1-n-butyryloxy-2,2-dichlorovinyl)phosphonic acid. Of the six compounds tested, dichlorvos and trichlorfon induced base pair substitutions and DNA damage. No mutagenicity and DNA damage were found in experiments with butonate, vinylbutonate, demethyl vinylbutonate and demethyl dichlorvos. Genotoxic activity for dichlorvos and the absence of both mutagenic and DNA damaging properties for its non-alkylating demethyl derivative favors the hypothesis that alkylation of DNA is the essential step for mutation induction by this organophosphate. Furthermore, the absence of genetic effects after treatment with vinylbutonate and demethyl dichlorvos does not support a crucial role of vinyl or allyl groups in side chains of organophosphates for genetic activity. Microsomal enzymes decreased genetic activity of dichlorvos and trichlorfon in vitro. No evidence for a role of metabolic activation in the mutagenic activity of any of these compounds was found.     

Interactions between eIF4AI and its accessory factors eIF4B and eIF4H

Ribonucleoprotein complexes (RNP) remodeling by DEAD-box proteins is required at all stages of cellular RNA metabolism. These proteins are composed of a core helicase domain lacking sequence specificity; flanking protein sequences or accessory proteins target and affect the core's activity. Here we examined the interaction of eukaryotic initiation factor 4AI (eIF4AI), the founding member of the DEAD-box family, with two accessory factors, eIF4B and eIF4H. We find that eIF4AI forms a stable complex with RNA in the presence of AMPPNP and that eIF4B or eIF4H can add to this complex, also dependent on AMPPNP. For both accessory factors, the minimal stable complex with eIF4AI appears to have 1:1 protein stoichiometry. However, because eIF4B and eIF4H share a common binding site on eIF4AI, their interactions are mutually exclusive. The eIF4AI:eIF4B and eIF4AI:eIF4H complexes have the same RNase resistant footprint as does eIF4AI alone (9–10 nucleotides [nt]). In contrast, in a selective RNA binding experiment, eIF4AI in complex with either eIF4B or eIF4H preferentially bound RNAs much longer than those bound by eIF4AI alone (30–33 versus 17 nt, respectively). The differences between the RNase resistant footprints and the preferred RNA binding site sizes are discussed, and a model is proposed in which eIF4B and eIF4H contribute to RNA affinity of the complex through weak interactions not detectable in structural assays. Our findings mirror and expand on recent biochemical and structural data regarding the interaction of eIF4AI's close relative eIF4AIII with its accessory protein MLN51.     

绿色荧光蛋白标记的葡萄糖转运蛋白4稳定表达细胞系的建立

目的:建立稳定表达EGFP标记的葡萄糖转运蛋白4的CHO细胞系,为研究GLUT4在CHO细胞中的转运调节机制奠定基础。方法:采用分子克隆方法构建GLUT4-EGFP的融合蛋白,在FLP-in的CHO细胞系中表达,潮霉素筛选后得到稳定的细胞系。结果:通过共聚焦显微镜的检测,证明了此稳定细胞系的阳性率达到了99%。定位研究表明大部分GLUT4以囊泡形式分布在CHO细胞胞浆内,但是质膜上也有少量的GLUT4。结论:建立了一个稳定表达GLUT4-EGFP的CHO细胞系,为进一步研究GLUT4的转运提供了一个很好的细胞模型。     

DHHC protein-dependent palmitoylation protects regulator of G-protein signaling 4 from proteasome degradation

Regulator of G-protein signaling 4 (RGS4), an intracellular modulator of G-protein coupled receptor (GPCR)-mediated signaling, is regulated by multiple processes including palmitoylation and proteasome degradation. We found that co-expression of DHHC acyltransferases (DHHC3 or DHHC7), but not their acyltransferase-inactive mutants, increased expression levels of RGS4 but not its Cys2 to Ser mutant (RGS4C2S). DHHC3 interacts with and palmitoylates RGS4 but not RGS4C2S in vivo. Palmitoylation prolongs the half-life of RGS4 by over 8-fold and palmitoylated RGS4 blocked α_1A-adrenergic receptor-stimulated intracellular Ca²⁺ mobilization. Together, our findings revealed that DHHC proteins could regulate GPCR-mediated signaling by increasing RGS4 stability.

Structured summary

MINT-8049215: Rgs4 (uniprotkb:P49799) physically interacts (MI:0915) with DHHC3 (uniprotkb:Q8R173) by anti-tag coimmunoprecipitation (MI:0007)     

On the origins and functions of the enzymes of the 4-chlorobenzoate to 4-hydroxybenzoate converting pathway

This review examines the enzymes of 4-chlorobenzoate to 4-hydroxybenzoate converting pathway found in certain soil bacteria. This pathway consists of three enzymes: 4-chlorobenzoate: Coenzyme A ligase, 4-chlorobenzoyl-Coenzyme A dehalogenase and 4-hydroxybenzoyl-Coenzyme A thioesterase. Recent progress made in the cloning and expression of the pathway genes from assorted bacterial strains is described. Gene order and sequence found among these strains are compared to reveal independent enzyme recruitment strategies. Sequence alignments made between thePseudomonas sp. strain CBS3 4-chlorobenzoate pathway enzymes and structurally related proteins contained within the protein sequence data banks suggest possible origins in preexisting -oxidation pathways. The purification and characterization of the physical and kinetic properties of the pathway enzymes are described. Where possible a comparison of these properties between like enzymes from different bacterial sources are made.     

重组融合蛋白EGF-E4orf4多聚体的鉴定及结构分析

目的:确认重组融合蛋白EGF-E4orf4为多聚体及其具有EGFR结合活性。方法:通过凝胶过滤层析、SDS-PAGE和免疫印迹分析重组融合蛋白EGF-E4orf4是否形成聚合物。利用动态光散射、静态光散射和圆二色谱测定EGF-E4orf4的分子半径、分子量和二级结构。应用流式细胞术分析EGF-E4orf4与细胞表面EGFR结合能力。结果:凝胶过滤等方法证实EGF-E4orf4形成了多聚体,光散射实验证明了EGF-E4orf4多聚体的分子量和分子半径分别为1.656×107Da、67.90nm,约为820聚体。圆二色谱表明该聚合体融合蛋白含有大量的β-折叠结构。受体结合实验证明该聚合物具有EGFR结合活性。结论:重组融合蛋白EGF-E4orf4以蛋白多聚体形式存在,可以与EGFR结合。因此,EGF-E4orf4作为一种新型靶向性抗肿瘤药物,具有潜在的临床应用前景。     

以ND4L和ND4基因为标记探讨黑腹果蝇种组的系统发育关系

多年来的形态学、染色体组学以及DNA序列几个方面的研究均没有很好地阐明黑腹果蝇种组内的系统发育关系。本实验测定了33个样品的ND4和31个样品的ND4L基因序列,以D．obscuroides为外群,用最大简约法和Bayesian法分别构建进化树。结果表明两种方法构建的拓扑结构一致,而且大部分支系的支持率较高。整个黑腹果蝇种组分成三大谱系：1）montium种亚组;2）ananssae种亚组;3）Oriental种亚组（melanogaster、ficsphila、eugracilis、elegans、suzukii、takahashii）。montium是最早分化的种亚组。在第三谱系中,melanogaster分化得最早;然后依次是ficsphila,eugracilis,elegans;suzukii与takahashii为姐妹种亚组,最后分化。     

Inhibition of Mitogen-activated Protein Kinase (MAPK)-interacting Kinase (MNK) Preferentially Affects Translation of mRNAs Containing Both a 5′-Terminal Cap and Hairpin

The MAPK-interacting kinases 1 and 2 (MNK1 and MNK2) are activated by extracellular signal-regulated kinases 1 and 2 (ERK1/2) or p38 in response to cellular stress and extracellular stimuli that include growth factors, cytokines, and hormones. Modulation of MNK activity affects translation of mRNAs involved in the cell cycle, cancer progression, and cell survival. However, the mechanism by which MNK selectively affects translation of these mRNAs is not understood. MNK binds eukaryotic translation initiation factor 4G (eIF4G) and phosphorylates the cap-binding protein eIF4E. Using a cell-free translation system from rabbit reticulocytes programmed with mRNAs containing different 5′-ends, we show that an MNK inhibitor, {"type":"entrez-protein","attrs":{"text":"CGP57380","term_id":"877393391","term_text":"CGP57380"}}CGP57380, affects translation of only those mRNAs that contain both a cap and a hairpin in the 5′-UTR. Similarly, a C-terminal fragment of human eIF4G-1, eIF4G(1357–1600), which prevents binding of MNK to intact eIF4G, reduces eIF4E phosphorylation and inhibits translation of only capped and hairpin-containing mRNAs. Analysis of proteins bound to m⁷GTP-Sepharose reveals that both CGP and eIF4G(1357–1600) decrease binding of eIF4E to eIF4G. These data suggest that MNK stimulates translation only of mRNAs containing both a cap and 5′-terminal RNA duplex via eIF4E phosphorylation, thereby enhancing the coupled cap-binding and RNA-unwinding activities of eIF4F.     

Identification of 4-acetoxyaminoquinoline from the hydrolysis of 1-acetoxy-4-acetoxyimino-1,4-dihydroquinoline,in vitro and in vivo properties

4-Acetoxyaminoquinoline (Ac-4-HAQ) (1) was identified as a hydrolysis product of 1-acetoxy-4-acetoxyimino-1,4-dihydroquinoline (diAc-4-HAQO). The reaction allowing the obtention of (1) obeys to a reduction mechanism implying the N₁-O cleavage. The carcinogenic properties of (1) observed by Sato et al. (Japan J. Exp. Med., 40 (1970) 475) in mice were studied in rats with the in vivo system we used previously with 4-nitroquinoline-1-oxide (4-NQO) and 4-hydroxyaminoquinoline-1-oxide (4-HAQO). In rats (1) does not covalently bind DNA. It was, therefore, possible to propose an interpretation of the results obtained by Enomoto et al. (Proc. Soc. Exp. Biol. Med., 136 (1971) 1206) who injected diAc-4-HAQO s.c. to mice and rats. Compound 1 could be responsible for the carcinogenic effects observed through the following pathway: (1) should be formed by hydrolysis of diAc-4-HAQO and reactivated by an enzymatic system to N-oxide derivative, the 4-acetoxyaminoquinoline-1-oxide (Ac-4-HAQO), which constitutes an ultimate carcinogen model of 4-NQO.     

中国湖北地区汉族家系补体第四成分（C4）单倍型的检测

用我室仿国际标准C4定型程序改进后建立的方法及羧肽酶B处理后C4分型方法对湖北地区93个无血缘关系的汉族家系进行C4单倍型的检测,对310个C4单倍型分析可见,我国汉族以A3B1频率最高(0.4194),A3B2次之(0.1161),A2B1与A4B2均为0.0903。以下依次是AQOB1(0.0645)、A3BQO(0.0548)、AQOBQO(0.0322)、A2B2(0.0256)、A4B1(0.0161)、A2B92(0.0129)等。从连锁不平衡参数(Δ)的卡方数值可见,A4B2、AQOBQO及A2B92具有极显著意义的阳性△值;而A4B1与AQOB2则具有极显著意义的阴性△值。将我们的结果与日本人、美国及德国白人,南非黑人的资料进行了对比,并进行了一些讨论。     

Phytosterols accumulation in the seeds of Linum usitatissimum L.

A comparative study was performed to determine the free sterols content and composition during the development of three varieties of linseed (H52, O116 and P129). Seed samples were collected at regular intervals from 7 to 60 days after flowering (DAF). Ten compounds were identified: cholesterol, campesterol, brassicasterol, stigmasterol, β-sitosterol, Δ5-avenasterol, cycloartenol; 24-methylene cycloartanol, obtusifoliol, citrostadienol. The maximum level of 4-desmethylsterols (1515 mg/100 g oil) was reached at 7 DAF in P129 variety. H52 had the highest level of 4-4 dimethylsterols (355 mg/100 g oil) at 28 DAF. The greatest amount of 4-monomethylsterols (35 mg/100 g oil) was detected in H52 at 14 DAF. During linseed development, β sitosterol (830 mg/100 g oil) was the major 4-desmethylsterols, followed by campesterol (564 mg/100 g oil) and stigmasterol (265 mg/100 g oil). Some of these compounds followed nearly the same accumulation pattern during linseed maturation.     

IL-4 和IL-12 在宫颈癌中的表达及对紫杉醇过敏的影响

目的:研究IL-4,IL-12在宫颈癌组织中的表达,探讨其对宫颈癌发生及术后对紫杉醇过敏的影响。方法:应用半定量逆反应-聚合酶链反应(RT-PCR)技术检测IL-4mRNA,IL-12p35以及IL-12p40 mRNA在正常宫颈组和宫颈癌组中的表达,并分析两者之间的相关性以对紫杉醇过敏的影响。结果:1.宫颈癌组中IL-4mRNA表达水平高于正常宫颈组,而IL-12p35和IL-12p40mRNA表达低于正常宫颈组,差异有统计学意义(P<0.05);2.在术后给予紫杉醇治疗的宫颈癌患者中,过敏组中IL-4mRNA的表达高于不过敏组;IL-12p35和IL-12p40mRNA则低于后者,差异有统计学意义(P<0.05)。结论:体内IL-12降低和(或)IL-4升高可促进宫颈癌的发生发展增加紫杉醇过敏的发生率。     

Rocaglates Induce Gain-of-Function Alterations to eIF4A and eIF4F

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The impact of chemokine receptor CXCR4 on breast cancer prognosis: A meta-analysis

Background: C-X-C chemokine receptor type 4 (CXCR4) has been implicated in the invasiveness and metastasis of diverse cancers. However, the published data remain controversial on the correlation between CXCR4 expression level, as well as its subcellular distribution in tumor cells, and the clinical outcome of patients with breast cancer. Methods: To identify the precise role of CXCR4 in the clinical outcome of breast cancer, we performed a meta-analysis including 15 published studies. Original data included the hazard ratios (HRs) of overall survival (OS) and disease-free survival (DFS) in breast cancer with high CXCR4 expression versus low expression. We pooled hazard ratios (HRs) with 95% confidence intervals (CIs) to estimate the hazard. Results: A total of 15 published studies (including 3104 patients) were eligible. Overall survival (OS) and disease-free survival (DFS) of breast cancer were found to be significantly related to CXCR4 expression level, with the HR being 1.65 (95%CI: 1.34–2.03; P < 0.00001) and 1.94 (95%CI: 1.42–2.65; P < 0.00001) respectively. Stratified analysis according to subcellular distribution of CXCR4 showed that high expression in whole cells, cytoplasm and nucleus could predict unfavorable OS, with the HR of 2.02 (95%CI: 1.43–2.85; P < 0.0001), 1.57 (95%CI: 1.13–2.18; P = 0.007), and 1.47 (95%CI: 1.19–1.81; P = 0.0004) respectively. As for DFS, elevated expression level of CXCR4 both in whole cells and cytoplasm predicted a poor outcome, with the HR being 2.23 (95%CI: 1.48–3.37; P = 0.0001) and 1.76 (95%CI: 1.11–2.80; P = 0.02), while high expression in the nucleus had no statistical significance, with HR 1.15 (95%CI: 0.52–2.55; P = 0.73). Conclusions: Increased CXCR4 expression, especially in whole cells and cytoplasm, may serve as a poor prognostic indicator in patients with breast cancer. Future studies are warranted to investigate the relationship between CXCR4 expression and survival of patients with breast carcinoma, which could help predict the clinical outcome and guide clinical decision-making for therapy.     

The structure of the O-polysaccharide from the lipopolysaccharide of Providencia alcalifaciens O30

The O-polysaccharide was obtained by mild acid degradation of the lipopolysaccharide of Providencia alcalifaciens O30. Studies by sugar and methylation analyses along with (1)H and (13)C NMR spectroscopy, including two-dimensional (1)H,(1)H COSY, TOCSY, ROESY, and H-detected (1)H,(13)C HSQC, HMBC, and HMQC-TOCSY experiments, showed that the polysaccharide has a linear pentasaccharide repeating unit of the following structure:     

Biomolecular response of oxanine in DNA strands to T4 polynucleotide kinase, T4 DNA ligase, and restriction enzymes

Oxanine (Oxa), generated from guanine (Gua) by NO- or HNO₂-induced nitrosative oxidation, has been thought to cause mutagenic problems in cellular systems. In this study, the response of Oxa to different enzymatic functions was explored to understand how similarly it can participate in biomolecular reactions compared to the natural base, Gua. The phosphorylation efficiency of the T4 polynucleotide kinase was highest when Oxa was located on the 5′-end of single stranded DNAs compared to when other nucleobases were in this position. The order of phosphorylation efficiency was as follows; Oxa > Gua > adenine (Ade) ∼ thymine (Thy) > cytosine (Cyt). Base-pairing of Oxa and Cyt (Oxa:Cyt) between the ligation fragment and template was found to influence the ligation performance of the T4 DNA ligase to a lesser degree compared to Gua:Cyt. In addition, EcoRI and BglII showed higher cleavage activities on DNA substrates containing Oxa:Cyt than those containing Gua:Cyt, while BamHI, HindIII and EcoRV showed lower cleavage activity; however, this decrease in activity was relatively small.     

Gesundheit und Ernährung: Die Macht der Kultur

Health and nutrition: The power of cultural patterns Despite enormous educational efforts and widely spread common knowledge about the subject, today's nutrition as it is practiced by many consumer groups concerning health in Germany, shows great potential to be optimized. On one side this is due to a cognitive dissonance: The knowledge about a healthy nutrition is opposed to a practice that is often detrimental to health. Among other factors, the main reasons for that phenomenon can be found within psychological aspects of nutrition: Practices that are tried and tested have a stabilizing effect and lead to emotional security. On the other side nutritional systems in principle change slowly and are difficult to control, especially since food itself and communicating about it function as ideological placings, as a representation of status or are matter of distinction in a society driven by modern lifestyles. Oftentimes supposedly reasonable nutritional practices hardly show any commonalities with these realities. Furthermore people who live in Germany but who were socialized with a different cultural background tend to have conceptions of a valuable nutrition that are often contradictorily to scientific findings. That also counts for people who obtain information from internet platforms that are not scientifically oriented. There they pick up superficial knowledge, esoteric beliefs or ideology‐based hints delivered through a science‐based appearance.     

大鼠胚胎发育期NBC1 在胰腺的表达与定位

目的:探讨碳酸氢钠协同转运载体(NBC1)在大鼠胰腺胚胎发育期不同阶段核酸、蛋白水平的动态变化以及在腺泡和β细胞的定位表达。方法:采用高密度寡核苷酸芯片对孕12.5 d(E12.5)、E15.5、E18.5、新生和成年胰腺进行基因转录水平分析,用RT-PCR和Western blot分别验证了NBC1核酸和蛋白在E15.5、E18.5、新生和成年时期胰腺中的表达情况,用Double fluorescence immunohistochemistry分析了NBC1在E18.5、新生和成年时期胰腺腺泡和β细胞的定位表达。结果:在大鼠胰腺胚胎发育过程中,NBC1核酸、蛋白在E18.5时特异高表达,新生下降直至成年最低;在腺泡基底侧膜和β细胞膜有强烈的阳性信号,且在成年胰腺中β细胞膜阳性信号较腺泡基底侧膜强。NBC1的表达变化与其功能近似基因的表达趋势相反,而与其协同发挥作用的基因及胰腺特异基因的表达趋势一致。结论:NBC1在胰腺发育过程中不仅与结构形成而且与功能发挥相关。