Synthesis, antibacterial activities and molecular docking studies of Schiff bases derived from N-(2/4-benzaldehyde-amino) phenyl-N'-phenyl-thiourea

A series of novel Schiff base derivatives have been designed and synthesized, and their biological activities were also evaluated as potential inhibitors of FabH. These compounds were assayed for antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis and Staphylococcus aureus. Compounds with potent antibacterial activities were tested for their E. coli FabH inhibitory activity. Compound 3v showed the most potent antibacterial activity with MIC of 1.56-6.25 μg/mL against the tested bacterial strains and exhibited the most potent E. coli FabH inhibitory activity with IC(50) of 4.3 μM. Docking simulation was performed to position compound 3v into the E. coli FabH active site to determine the probable binding conformation.     

Fen1 mutations that specifically disrupt its interaction with PCNA cause aneuploidy-associated cancer

DNA replication and repair are critical processes for all living organisms to ensure faithful duplication and transmission of genetic information. Flap endonuclease 1 (Fen1), a structure-specific nuclease, plays an important role in multiple DNA metabolic pathways and maintenance of genome stability. Human FEN1 mutations that impair its exonuclease activity have been linked to cancer development. FEN1 interacts with multiple proteins, including proliferation cell nuclear antigen (PCNA), to form various functional complexes. Interactions with these proteins are considered to be the key molecular mechanisms mediating FEN1's key biological functions. The current challenge is to experimentally demonstrate the biological consequence of a specific interaction without compromising other functions of a desired protein. To address this issue, we established a mutant mouse model harboring a FEN1 point mutation (F343A/F344A, FFAA), which specifically abolishes the FEN1/PCNA interaction. We show that the FFAA mutation causes defects in RNA primer removal and long-patch base excision repair, even in the heterozygous state, resulting in numerous DNA breaks. These breaks activate the G2/M checkpoint protein, Chk1, and induce near-tetraploid aneuploidy, commonly observed in human cancer, consequently elevating the transformation frequency. Consistent with this, inhibition of aneuploidy formation by a Chk1 inhibitor significantly suppressed the cellular transformation. WT/FFAA FEN1 mutant mice develop aneuploidy-associated cancer at a high frequency. Thus, this study establishes an exemplary case for investigating the biological significance of protein-protein interactions by knock-in of a point mutation rather than knock-out of a whole gene.     

Sigma B对单核细胞增生李斯特菌耐受抗生素作用的影响

单核细胞增生李斯特菌是重要的革兰阳性食源性致病菌。近年来的报道显示出该菌耐受抗生素的能力有不断增强的趋势,为了探讨其耐药机制,对Sigma B（σB,李斯特菌中应对环境胁迫的主要调控因子）在抗生素耐受性中的作用进行了初步研究。检测和比较单核细胞增生李斯特菌标准菌株EGDe和其σB缺失突变菌株EGDeΔsigB对盘尼西林青霉素、氨苄西林青霉素、利福平、硫酸庆大霉素、四环素盐酸和红霉素6种抗生素的最小抑菌浓度（MIC）;在测定的MIC的基础上,利用MTT（噻唑蓝活体染色法）法比较EGDe和EGDeΔsigB在1×MIC、2×MIC和8×MIC的氨苄西林青霉素、红霉素和利福平3种抗生素中的生长活性。EGDe对盘尼西林青霉素（0.16μg/mL）、四环素盐酸（0.25μg/mL）和硫酸庆大霉素（0.5μg/mL）的MIC高于EGDeΔsigB（分别为0.08、0.125和0.125μg/mL）;而对氨苄西林青霉素、红霉素和利福平的MIC 2种菌株没有差别,分别为0.19、0.125和0.032μg/mL;与EGDe相比,EGDeΔsigB在氨苄西林青霉素、红霉素和利福平培养基中的生长活性较差,对抗生素的抑制更为敏感,而且随着这3种抗生素浓度的增加,其抑制程度也随之增强。Sigma B在单核细胞增生李斯特菌对抗生素的耐受中起到重要调节作用。     

基于RAPD技术探讨黄精属部分药用植物系统位置

目的：从分子水平探讨黄精属部分药用植物间的系统位置。方法：采用RAPD分子标记方法,以同科万寿竹属植物宝铎草（Disporum sessile D．Don）为外类群,对百合科黄精属19批（6种）药用植物进行基因组DNA的多态性分析,通过聚类分析探讨黄精种属间亲缘关系。结果：筛选出7条随机引物,聚类结果表明,黄精属植物在属级分类上特征明显,但属内分类有交叉。结论：RAPD技术可以为黄精属的分类和种的鉴别提供一定的理论依据。     

Assembly mechanism of [Fe2S2] cluster in ferredoxin from Acidithiobacillus ferrooxidans

Ferredoxin is a typical iron-sulfur protein that is ubiquitous in biological redox systems. This study investigates the in vitro assembly of a [Fe2S2] cluster in the ferredoxin from Acidithiobacillus ferrooxidans in the presence of three scaffold proteins: IscA, IscS, and IscU. The spectra and MALDI-TOF MS results for the reconstituted ferredoxin confirm that the iron-sulfur cluster was correctly assembled in the protein. The inactivation of cysteine desulfurase by L-allylglycine completely blocked any [Fe2S2] cluster assembly in the ferredoxin in E. coli, confirming that cysteine desulfurase is an essential component for iron-sulfur cluster assembly. The present results also provide strong evidence that [Fe2S2] cluster assembly in ferredoxin follows the AUS pathway.     

CDH1 -160C>A gene polymorphism is an ethnicity-dependent risk factor for gastric cancer

The associations between E-cadherin (CDH1) gene polymorphisms and gastric cancer (GC) susceptibility are still controversial. Given this uncertainty, we carried out a meta-analysis of published case-control studies to derive more precise estimations of these relationships. Relevant studies were identified from PubMed and EMBASE up to March 2011. Seventeen studies with 3511 GC cases and 4826 controls were selected. Crude odds ratios (OR) and 95% confidence intervals (CI) were used to investigate the strength of the associations. No associations between CDH1 (+54T>C, -160C>A, -347G>GA, -616G>C, -2076C>T and -3159T>C) gene polymorphisms and GC risk for all genetic models were found. As for CDH1 -160C>A polymorphism, subgroup analyses by country, gender, study design, smoking status, Helicobacter pylori infection, and the Lauren classification of GC did not change the results. When stratified by ethnicity, we found the A allele carriers had a significantly increased risk of GC among Caucasians (AA vs. CA+CC: OR=1.50, 95% CI=1.03-2.19, P=0.03), but not among Asians (AA vs. CA+CC: OR=0.87, 95% CI=0.56-1.37, P=0.56). No publication bias was found in the present study. This meta-analysis suggests that CDH1 -160C>A gene polymorphism may contribute to increased risk of GC among Caucasians.     

miR-223 regulates migration and invasion by targeting Artemin in human esophageal carcinoma

Background

Artemin (ARTN) is a neurotrophic factor belonging to the glial cell-derived neurotrophic factor family of ligands. To develop potential therapy targeting ARTN, we studied the roles of miR-223 in the migration and invasion of human esophageal carcinoma.

Methods

ARTN expression levels were detected in esophageal carcinoma cell lines KYSE-150, KYSE-510, EC-9706, TE13, esophageal cancer tissues and paired non-cancerous tissues by Western blot. Artemin siRNA expression vectors were constructed to knockdown of artemin expression mitigated migration and invasiveness in KYSE150 cells. Monolayer wound healing assay and Transwell invasion assay were applied to observe cancer cell migration and invasion. The relative levels of expression were quantified by real-time quantitative PCR.

Results

ARTN expression levels were higher in esophageal carcinoma tissue than in the adjacent tissue and was differentially expressed in various esophageal carcinoma cell lines. ARTN mRNA contains a binding site for miR-223 in the 3'UTR. Co-transfection of a mir-223 expression vector with pMIR-ARTN led to the reduced activity of luciferase in a dual-luciferase reporter gene assay, suggesting that ARTN is a target gene of miR-223. Overexpression of miR-223 decreased expression of ARTN in KYSE150 cells while silencing miR-223 increased expression of ARTN in EC9706 cells. Furthermore, overexpression of miR-223 in KYSE150 cells decreased cell migration and invasion. Silencing of miR-223 in EC9706 cells increased cell migration and invasiveness.

Conclusions

These results reveal that ARTN, a known tumor metastasis-related gene, is a direct target of miR-223 and that miR-223 may have a tumor suppressor function in esophageal carcinoma and could be used in anticancer therapies.     

Galactosylated N-2-hydroxypropyl methacrylamide-b-N-3-guanidinopropyl methacrylamide block copolymers as hepatocyte-targeting gene carriers

As alternatives of viral and cationic lipid gene carriers, cationic polymer-based vectors may provide flexible chemistry for the attachment of targeting moieties. In this report, galactosylated N-2-hydroxypropyl methacrylamide-b-N-3-guanidinopropyl methacrylamide block copolymers (galactosylated HPMA-b-GPMA block copolymers, or abbreviated as GHG) were prepared in order to develop hepatocyte targeting gene transfection carriers. The block copolymers were synthesized by aqueous reversible addition-fragmentation chain transfer (RAFT) polymerization of N-2-hydroxypropyl methacrylamide (HPMA) and N-3-aminopropyl methacrylamide (APMA), followed by galactosylation and guanidinylation. The molecular weight of GHG copolymers determined by static light scattering method was in the range from 48?600 to 76?240 g/mol. In addition, the galactose content in the GPMA block in the copolymers was determined to be 6.5-8.0 mol % according to the sulfuric acid method. The GHG copolymers complexed completely with plasmid DNA (pDNA) to show positive zeta-potential values with diameter 100-250 nm from charge ratio of 4, which demonstrated the excellent DNA condensing ability of guanidino groups. Furthermore, the MTT assay data of GHG/pDNA complexes on HepG2 cells and HeLa cells indicated that GHG copolymers had significantly lower cytotoxicity than PEI. In addition, the copolymers with GPMA component from 30.23% showed higher transfection efficiency than PEI at charge ratio of 12 in HepG2 cells. The result revealed that the conjugation of galactose groups in the copolymers brought asialoglycoprotein-receptor (ASGP-R) mediated transfection. The employing of HPMA component decreased the aggregation of protein in transfection presence of serum. The GHG copolymers combined the advantages of galactose moieties, guanidino groups, and HPMA component might show potential in safe hepatocyte targeting gene therapy.     

扩增和纯化携带肌浆网钙ATP酶重组腺病毒的实验方法

目的:通过扩增和纯化rAd.SERCA2a,为转SERCA2a基因研究提供实验基础,并为建立基因库提供稳定可靠的实验方法.方法:用100μL 1.9×10<'12>pfu/ml rAd.SERCA2a感染HEK293细胞,出现细胞病变效应时收获细胞,经物理反复冻融方法及两步氯化铯超速离心方法获得纯化的rAd.SERCA2a,紫外分光光度计比色法测定病毒DNA质粒数.结果:rAd.SERCA2a成功在HEK293细胞表达呈现绿色荧光,纯化的rAd-SERCA2a-GFP DNA质粒数为1.3±0.58×10<'12>pfu/mL,OD<,260>/OD<,280>比值为1.57±0.49(n=50).结论:建立了稳定可靠的借助HEK293细胞培养扩增rAd.SERCA2a的实验方法,纯化后的高效价的SERCA2a基因的重组腺病毒可直接用于心力衰竭的实验研究,对重组腺病毒携带其他基因的扩增与提纯方法也具有一定的参考价值.