Suppression of centrosome duplication and amplification by deacetylases

Centrosome duplication is controlled both negatively and positively by a number of proteins. The activities and stabilities of those regulatory proteins are in many cases controlled by posttranslational modifications. Although acetylation and deacetylation are highly common posttranslational modifications, their roles in the regulation of centrosome duplication had not been closely examined. Here, through focusing on the deacetylases, we investigated the role of acetylation/deacetylation in the regulation of centrosome duplication and induction of abnormal amplification of centrosomes. We found that the deacetylation event negatively controls centrosome duplication and amplification. Of the 18 total known deacetylases (HDAC1–11, SIRT1–7), ten deacetylases possess the activity to suppress centrosome amplification, and their centrosome amplification suppressing activities are strongly associated with their abilities to localize to centrosomes. Among them, HDAC1, HDAC5 and SIRT1 show the highest suppressing activities, but each of them suppresses centrosome duplication and/or amplification with its unique mechanism.     

来源于家蝇、地鳖虫、黄粉虫和河虾壳几丁糖的基本特性

为了了解昆虫来源几丁糖的基本特性及其与河虾来源几丁糖的差别,用同一方法在相同条件下分别以河虾壳(shell of Procambarus clarkii)、家蝇蛹壳(pupa shell ofMusca domestica vicinaMacquart)、地鳖虫壳(shell of Euplyphaga Walker)和黄粉虫蜕(exuviate of Tnebrio molitorL.)为来源制备的几丁糖在灰份、脱乙酰度、分子质量等及红外图谱上进行比较研究。昆虫来源几丁糖,其灰份低于河虾壳来源几丁糖;家蝇蛹壳几丁糖分子质量明显低于其他3种来源的几丁糖;从几丁糖质量角度看,采用家蝇蛹壳和地鳖虫壳可制备脱乙酰度较高的几丁糖;4种来源的几丁糖红外光谱图谱基本一致,具有几丁糖的特征吸收峰。     

Lasonolide A,a potent and reversible inducer of chromosome condensation

Lasonolide A (LSA) is a natural product with high and selective cytotoxicity against mesenchymal cancer cells, including leukemia, melanomas and glioblastomas. Here, we reveal that LSA induces rapid and reversible premature chromosome condensation (PCC) associated with cell detachment, plasma membrane smoothening and actin reorganization. PCC is induced at all phases of the cell cycle in proliferative cells as well as in circulating human lymphocytes in G₀. It is independent of Cdk1 signaling, associated with cyclin B downregulation and induced in cells at LSA concentrations that are three orders of magnitude lower than those required to block phosphatases 1 and 2A in vitro. At the epigenetic level, LSA-induced PCC is coupled with histone H3 and H1 hyperphosphorylation and deacetylation. Treatment with SAHA reduced LSA-induced PCC, implicating histone deacetylation as one of the PCC effector mechanisms. In addition, PCC is coupled with topoisomerase II (Top2) and Aurora A hyperphosphorylation and activation. Inhibition of Top2 or Aurora A partially blocked LSA-induced PCC. Our findings demonstrate the profound epigenetic alterations induced by LSA and the potential of LSA as a new cytogenetic tool. Based on the unique cellular effects of LSA, further studies are warranted to uncover the cellular target of lasonolide A (“TOL”).     

细菌体内乙酰化修饰研究进展

翻译后修饰是指前体蛋白经过一系列加工修饰形成具有多种功能的蛋白质,其可以发生在不同的氨基酸侧链或肽键上,通常是由酶活性介导的.5％的蛋白质组组成的酶介导了超过200多种的翻译后修饰类型,其中乙酰化修饰是一种重要的翻译后修饰途径.乙酰化修饰在真核细胞中被广泛研究,其几乎参与细胞的所有生理活动并且高度保守.最近的很多研究表...     

Synthesis of glycosides in which the aglycon is an N-(Hydroxymethyl)amino-1,3,5-triazine derivative

The synthesis of analogues of the anti-tumour drug 2-[N-(hydroxymethyl)methylamino]-4,6-bis (dimethylamino)-1,3,5-triazine (HMPMM) in which the OH or a dimethylamino group is replaced by a carbohydrate has been explored. Triazinyl β-glycosides were readily prepared by reaction of sugars with trimethyl-triazinylammonium salts. These were made with one or two methylamino groups on the triazine for reaction with formaldehyde to give the cytotoxic NMeCH2OH group. However, reaction of the triazinyl glycosides with formaldehyde gave complex intractable mixtures. When the carbohydrate portion was changed to the fully protected 2,3,4,6-tetra-O-acetyl glucose a good yield of the 2-[N-(hydroxymethyl)methylamino]-4-(dimethylamino)-1,3,5-triazin-2-yl tetra-O-acetyl β-glucoside was obtained. However, de-acetylation using sodium methoxide also removed the N–CH2OH group. We are investigating protection of the base-sensitive N–CH2OH group as trialkylsilyl and benzyl ethers and are looking at de-acetylation methods that are more selective. We have prepared glycosides in which the sugar is joined through the oxygen of the NMeCH2OH group. Coupling of acetobromoglucose with HMPMM catalysed by silver salts was not successful. Although methyl and cyclohexyl derivatives of HMPMM may be produced in high yields by reaction of HMPMM with methyl and cyclohexyl alcohols under acidic catalysis, production of glycosides in this way gave poor yields. MNDO calculations on reactions of HMPMM helped us devise improved reaction conditions for the condensation of 2,3,4,6-tetra-O-acetyl glucose with HMPMM and its derivatives. The best procedure to generate one of the target glycosides is to react 2,3,4,6-tetra-O-acetyl glucose and formaldehyde with 2-methylamino- 4,6-bis(dimethylamino)-1,3,5-triazine. The β-glycoside product was de-acetylated using potassium carbonate in dry methanol. Abbreviations: HMM, hexamethylmelamine (2) or 2,4,6-tris(dimethylamino)-1,3,5-triazine; HMPMM, hydroxymethylpentamethylmelamine or 2-[N-(hydroxymethyl)-methylamino]-4,6-bis(dimethylamino)-1,3,5-triazine; PMM, Pentamethylmelamine or 2-methylamino-4,6-bis(dimethylamino)-1,3,5-triazine; TBMS, t-Butyldimethylsilyl; p-TSA, p-Toluenesulphonic acid This revised version was published online in November 2006 with corrections to the Cover Date.     

流式细胞术检测组蛋白乙酰化水平方法的建立与应用

组蛋白去乙酰化酶抑制剂是近年来出现的一类新的抗肿瘤药物,在艾滋病等其他疾病中同样也受到关注。但是在基础和临床研究中,目前还缺乏统一可靠的组蛋白乙酰化水平的检测手段。本文利用全血和外周血单个核细胞,通过一系列的对比实验,比较了不同样品处理温度(冰上和室温)、破膜方法(细胞内因子染色破膜和核内因子染色破膜)、抗体剂量(抗体滴定)和抗体孵育时间(时间梯度)等实验条件对流式细胞术检测的影响,最终建立了一套基于流式细胞术的组蛋白乙酰化水平检测手段。同时,将优化后的流式细胞检测技术应用于西达本胺(目前国内唯一上市的组蛋白去乙酰化酶抑制剂)的体外实验和临床试验,结果均证明本文建立的组蛋白乙酰化流式细胞检测方法可以作为基础和临床研究中一个可靠、快速、便捷的检测手段。     

Regioselective formation of 6-O-acylsucroses and 6,3'-di-O-acylsucroses via the stannylene acetal method

Regioselective formation of 6-O-acylsucroses and 6,3′-di-O-acylsucroses in one pot with good yields was achieved for the first time by a typical acylation method of sucrose via its dibutylstannylene acetal. Pure monoesters at OH-6 and diesters at OH-6,3′ obtained by these procedures were readily isolated by simple column chromatography, thus overcoming the main difficulties associated with regioselectivity, efficiency, and isolation techniques for the practical preparation. Explanations for the regioselectivities observed during this stannylene acetal-mediated reaction were also proposed based on the structures of the stannylene acetal in solution and the intramolecular migration of stannylenes.     

Deacetylation of furanosides using banana as biocatalyst

The deacylation under hydrolytic conditions of methyl 2,3,5-tri-O-acetyl--d-ribofuranoside, methyl 2,3,5-tri-O-acetyl-β-d-ribofuranoside, methyl 2,3,5-tri-O-acetyl-,β-d-arabinofuranosides and alkyl 2,3,5-tri-O-acetyl-,β-xylofuranosides have been studied using banana whole tissue as biocatalyst. Reaction regioselectivity strongly depends on substrate structure. Hydrolysis of methyl 2,3,5-tri-O-acetyl--d-ribofuranoside afforded methyl 2,3-di-O-acetyl--d-ribofuranoside in quantitative yield.     

组蛋白去乙酰化酶抑制剂(HDACi)对小麦基因编辑效率的影响及转录组学分析

主要研究组蛋白去乙酰化酶抑制剂(HDACi)与染色质状态以及CRISPR/Cas9的编辑效率之间的关系。利用不同浓度的尼克酰胺(0,2.5和5 mmol/L)和丁酸钠(0,5和10 mmol/L)对小麦幼苗处理7 d和14 d,结果显示丁酸钠处理会抑制幼苗的生长,而尼克酰胺对幼苗影响较小。对尼克酰胺处理的小麦幼苗进行转录组测序,发现了一些有利于促进染色质状态开放的基因:6个甲基转移酶合成通路基因。此外对未发生编辑的TaAGO4a基因编辑转基因小麦材料的T2代进行尼克酰胺处理,结果显示5 mmol/L处理14 d时检测到1株3A和3B基因组均杂合编辑的植株,编辑效率从0提高到8.3%,其它处理组和对照组均没有检测到编辑。本研究证明尼克酰胺确实可以提高小麦基因编辑效率,为提高小麦基因编辑效率提供了一种新策略。