beta1-Integrins determine the dendritic morphology which enhances DC-SIGN-mediated particle capture by dendritic cells

The morphology of antigen-presenting dendritic cells (DCs) is characterized by the presence of numerous long dendrites. The formation of these processes is shown to require the interaction between the beta1-integrin (CD29) on the surface of the DCs and fibronectin in the extracellular matrix. This interaction occurs at focal contacts formed at the tips of dendrites, which contain high concentrations of the beta1-integrins, actin and the cytoskeletal proteins vinculin, paxillin and talin. Dendrites contain an extensive microtubule (MT) network, and are retracted in the presence of the MT inhibitor colchicine, suggesting that MTs are essential for dendrite stability. The dendritic morphology is shown to contribute directly to an enhanced ability to capture dendritic cell specific ICAM-3 grabbing nonintegrin (DC-SIGN)-coated beads. Time-lapse photography demonstrates that dendrites are highly dynamic structures, with cells extending and retracting multiple dendrites in different directions over a 3-h period. This motility increases the area scanned by an individual DC by over 2-fold. The unusual combination of a dendritic morphology and high motility is likely to play a major role in the efficient function of DCs as sentinels of the immune system.     

风车子抑素A4及其衍生物的研究进展

从南非一种风车子属植物Combretum caffrum树干中提取分离得到的二苯乙烯类化合物风车子抑素（combretastatin) A4(CA4)是目前已知微管蛋白抑制剂中活性最强的化合物之一。CA4对多种肿瘤细胞具有毒性作用,对一部分多药耐药癌细胞也有较强的抑制活性。目前已合成上百个CA4的衍生物,并筛选出一些新药候选物。CA4的水溶性磷酸盐前药CA4P正在美国进行Ⅲ期临床试验。本文简要介绍CA4药理作用及其作用机制,重点综述CA4衍生物的研究进展。     

Determination of noscapine's localization and interaction with the tubulin-α/β heterodimer

Noscapine, the benzylisoquinoline alkaloid, 5-(4,5-Dimethoxy-3-oxo-1,3-dihydro-isobenzofuran-1-yl)-4-methoxy-6-methyl-5,6,7,8-tetrahydro-[1,3]dioxolo[4,5-g]isoquinolin-6-ium, has been extensively used as a cough-suppressing medication with low toxicity. It has been recently shown to also have anti-cancer activity in mice and humans. In this work, using in silico analyses, the most probable binding site for noscapine is identified to be at the intradimer region of the α and β subunits of the tubulin heterodimer. By utilization of small molecule docking techniques, and an analysis of the thermodynamically favorable binding modes of noscapine in its binding site, the key residues of tubulin monomers interacting with noscapine are determined. Upon noscapine binding, the conformational change in the tubulin heterodimer along with a potential long-range allosteric effect on both the N and E sites is studied by means of molecular dynamics simulations. Noscapine is found to function as a tubulin-stabilizing agent that interacts strongest with the lateral and longitudinal segments of the tubulin dimer, impacting the interaction between monomers in neighboring protofilaments. We infer that this may act as a depolymerization inhibitor of microtubules. As a result of this study, we have designed novel analogues of noscapine with the ultimate goal of finding agents with increased anti-tumor activity and lower inhibitory concentrations than that of noscapine.     

Design, synthesis, and cytotoxicity of novel 3-arylidenones derived from alicyclic ketones

Forty-four novel chalcone-inspired analogs having a 3-aryl-2-propenoyl moiety derived from alicyclic ketones were designed, synthesized, and investigated for cytotoxicity against murine B16 and L1210 cancer cell lines. The analogs belong to four structurally divergent series, three of which (series g, h, and i) contain differently substituted cyclopentanone units and the fourth (series j) contains a 3,3-dimethyl-4-piperidinone moiety. Of these, the analogs in series j showed potential cytotoxic activity against murine B16 (melanoma) and L1210 (lymphoma) cells. The most active compounds 5j, 11j, 15j, and 12h produced IC(50) values from 4.4 to 15 μm against both cell lines. A single-crystal X-ray structure analysis and molecular modeling studies confirmed that these chalcones have an E-geometry about the alkene bond and possess a slightly 'twisted' conformation similar to that of combretastatin A-4. At a concentration of 30 μm, compounds 5j, 11j, and 15j did not cause microtubule depolymerization in cells, suggesting that they have a different mechanism of action.     

风车子抑素A4及其衍生物的研究进展

从南非一种风车子属植物Combretum caffrum树干中提取分离得到的二苯乙烯类化合物风车子抑素（combretastatin）A4（CA4）是目前已知微管蛋白抑制剂中活性最强的化合物之一。CA4对多种肿瘤细胞具有毒性作用,对一部分多药耐药癌细胞也有较强的抑制活性。目前已合成上百个CA4的衍生物,并筛选出一些新药候选物。CA4的水溶性磷酸盐前药CA4P正在美国进行Ⅲ期临床试验。本文简要介绍CA4药理作用及其作用机制,重点综述CA4衍生物的研究进展。     

Heterocyclic Organobismuth(III) Compound Targets Tubulin to Induce G2/M Arrest in HeLa Cells

Our previous study showed that organobismuth compounds induce apoptosis in human promyelocytic leukemia cells, although solid tumor cell lines were relatively resistant. Herein, we investigated the primary cellular target of these compounds in HeLa cells. One organobismuth compound, bi-chlorodibenzo[c,f][1,5]thiabismocine (compound 3), arrested the cell cycle at G₂/M as assessed by flow cytometry and by upregulating the expression of cyclin B1. At a low concentration (0.5 μM), compound 3 caused cell cycle arrest at the mitotic phase and induced apoptosis. At a higher concentration (>1.0 μM), it induced an arrest in the G₂/M phase, leading to apoptosis. In many cells blocked at the M phase, the organization of microtubules was affected, indicating depolymerization of the microtubule network. Western blotting demonstrated that compound 3 depolymerized microtubules similar to colchicine and nocodazole. Experiments in vitro also showed that compound 3 inhibited the assembly of purified tubulin in a concentration-dependent manner by interacting with the colchicine-binding site of tubulin through its SH groups. Heterocyclic organobismuth compounds are novel tubulin ligands.     

Synthesis and Antiproliferative Activities of Ottelione A Analogues

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N-(4-iodophenyl)-N'-(2-chloroethyl)urea as a microtubule disrupter: in vitro and in vivo profiling of antitumoral activity on CT-26 murine colon carcinoma cell line cultured and grafted to mice

The antitumoral profile of the microtubule disrupter N-(4-iodophenyl)-N'-(2-chloroethyl)urea (ICEU) was characterised in vitro and in vivo using the CT-26 colon carcinoma cell line, on the basis of the drug uptake by the cells, the modifications of cell cycle, and beta-tubulin and lipid membrane profiles. N-(4-iodophenyl)-N'-(2-chloroethyl)urea exhibited a rapid and dose-dependent uptake by CT-26 cells suggesting its passive diffusion through the membranes. Intraperitoneally injected ICEU biodistributed into the grafted CT-26 tumour, resulting thus in a significant tumour growth inhibition (TGI). N-(4-iodophenyl)-N'-(2-chloroethyl)urea was also observed to accumulate within colon tissue. Tumour growth inhibition was associated with a slight increase in the number of G2 tetraploid tumour cells in vivo, whereas G2 blockage was more obvious in vitro. The phenotype of beta-tubulin alkylation that was clearly demonstrated in vitro was undetectable in vivo. Nuclear magnetic resonance analysis showed that cells blocked in G2 phase underwent apoptosis, as confirmed by an increase in the methylene group resonance of mobile lipids, parallel to sub-G1 accumulation of the cells. In vivo, a decrease of the signals of both the phospholipid precursors and the products of membrane degradation occurred concomitantly with TGI. This multi-analysis established, at least partly, the ICEU activity profile, in vitro and in vivo, providing additional data in favour of ICEU as a tubulin-interacting drug accumulating within the intestinal tract. This may provide a starting point for researches for future efficacious tubulin-interacting drugs for the treatment of colorectal cancers.     

膳食锌对小鼠中枢神经系统微管蛋白表达的影响

目的　通过观察中枢神经系统 (CNS)中 α-微管蛋白 (α- Tub)及 β-微管蛋白 (β-Tub)的表达 ,探讨膳食锌调节 CNS微管聚合作用的可能机制。方法　 80只刚怀孕 ICR母鼠随机分为严重缺锌组、轻度缺锌组、适锌组、高锌组和高锌对喂组五组 ,在孕期和哺乳期分别饲喂含 1、5、30、1 0 0和 1 0 0 mg/ kg锌水平的实验饲料 ;断奶期 (仔鼠 2 0日龄 )后各组均改喂普通饲料。取各实验组动物第 1 0天胚胎 (E1 0 )头和身体、及第 1 5天胚胎 (E1 5 )、出生第 1天 (P1 )、第 5天 (P5 )、第 1 0天(P1 0 )、第 2 0天 (P2 0 )和第 70天 (P70 ,成年 )大脑、小脑和肝组织 ,采用 Western blot技术检测其 α-Tub和 β- Tub表达情况。结果　实验仔鼠从胚胎早期 (E1 0 )至发育成熟 (P70 ) CNS中均有微管蛋白 (Tub)表达 ,而肝组织中未见有 Tub印迹出现 ;α- Tub和 β- Tub在大脑和小脑的表达模式相似 ,即发育早期有上调趋势 ,达到表达高峰 (P5～P1 0 )后表达量逐步下调 ,α- Tub在 P5达到表达高峰 ,而β- Tub在 P1 0达到表达高峰 ;比较实验组各期 Tub表达水平 ,依次为 1 mg/ kg组 <5 mg/ kg组<30 mg/ kg组 <1 0 0 mg/ kg组 ,大脑和小脑 α- Tub、β- Tub水平与膳食锌水平具有明显的依赖关系。结论　发育期锌缺乏可抑制 CNS中 α-