Localization of human SMC1 protein at kinetochores

Proper cohesion of sister chromatids is prerequisite for correct segregation of chromosomes during cell division. The cohesin multiprotein complex, conserved in eukaryotes, is required for sister chromatid cohesion. Human cohesin is composed of a stable heterodimer of the structural maintenance of chromosomes (SMC) family proteins, hSMC1 and hSMC3, and non-SMC components, hRAD21 and SA1 (or SA2). In yeast, cohesin associates with chromosomes from late G1 to metaphase and is required for the establishment and maintenance of both chromosome arm and centromeric cohesion. However, in human cells, the majority of cohesin dissociates from chromosomes before mitosis. Although it was recently shown that a small amount of hRAD21 localizes to the centromeres during metaphase, the presence of other cohesin components at the centromere has not been demonstrated in human cells. Here we report the mitosis-specific localization of hSMC1 to the kinetochores. hSMC1 is targeted to the kinetochore region during prophase concomitant with kinetochore assembly and remains through anaphase. Importantly, hSMC1 is targeted only to the active centromere on dicentric chromosomes. These results suggest that hSMC1 is an integral component of the functional kinetochore structure during mitosis. This revised version was published online in July 2006 with corrections to the Cover Date.     

菊苣提取物amyrin对家兔主动脉平滑肌细胞膜微粘度的影响

目的观察菊苣提取物α ａｍｙｒｉｎ对高糖高脂环境中家兔主动脉平滑肌细胞（ＳＭＣ）膜微粘度及过氧化脂质（ＬＰＯ）含量的影响。方法采用两种离体方法对比观察,即以家兔灌服该提取物后获取的含药物血清加至细胞培养基中的血清药理学方法和将提取物直接加至培养基中的直接体外给药法。结果两种方法给药均可降低高脂高糖模型细胞膜微粘度、改善细胞膜流动性,降低培养液中ＬＰＯ含量;两者之间作用强度无明显差异。结论该提取物具有一定的对抗ＳＭＣ高糖高脂损伤的药理活性;且在体内外对ＳＭＣ膜流动性作用相似;可能是菊苣防治糖尿病大血管并发症的重要组分之一。     

前列腺素E1对人肠系膜动脉平滑肌细胞钙激活钾通道活动的影响

目的：探讨前列腺素E1（PGE1）对人肠系膜动脉平滑肌细胞钙激活钾通道（KCa）活动的影响。方法：选择因消化道疾病手术而无血管病变的患者的肠系膜动脉小分支,用酶消化法获得单个平滑肌细胞（SMC）,应用膜片钳技术观察PGE1对KCα的影响。结果：在内面向外膜片下,PGE1可使KCa开放概率（Po）增加,平均开放时间（To）延长,平均关闭时间（Tc）缩短,并增大单通道电流幅值。结论：PGE1激活KCa,增加K^ 外流,引起细胞膜超极化从而舒张血管。     

天鹅记忆接骨器体内生物相容性研究

目的探讨NiTi合金天鹅记忆接骨器（SMC）在人体长期植入后的生物相容性。方法从临床上肢长管状骨骨折病例中随机选取病例，分别采用SMC内固定和进口不锈钢板内固定。待骨折愈合后手术取出内固定的同时取少量与金属密切接触的软组织界膜进行大体、光镜及电镜观察，比较不同性质内固定材料对骨折周围软组织的影响。结果SMC组软组织均无肉眼可见的炎性反应，为规则致密的纤维结缔组织，成纤维细胞为主要细胞成分，与正常纤维组织相连续，所在局部无明显软组织异常增生及变性，组织修复过程良好，未见变色、腐蚀和明显异物反应迹象；而不锈钢组则出现了较之严重的炎性反应，组织结构紊乱、成纤维细胞形态与周围胶原纤丝紊乱。结论SMC固定骨折后其对局部损害较轻，炎症反应轻或无，生物相容性及耐腐蚀性表现优于不锈钢板，是一种理想的生物医用材料。     

Lampbrush chromosomes enable study of cohesin dynamics

The lampbrush chromosomes present in the nuclei of amphibian oocytes offer unique biological approaches for study of the mechanisms that regulate chromatin structure with high spatial resolution. We discuss fundamental aspects of the remarkable organization and plasticity exhibited by lampbrush chromosomes. We then utilize lampbrush chromosomes to characterize the chromosomal distribution and dynamics of cohesin, the four-protein complex (RAD21/MCD1/SCC1, SMC1, SMC3, SCC3/SA2) responsible for sister chromatid cohesion. We find that endogenous SMC3 and newly expressed hRAD21 co-localize on chromosomal axes, sites where sister chromatids are tightly paired. We present evidence suggesting that hRAD21 recruitment to lampbrush chromosomes is modulated by chromosomal SMC1 and SMC3. Notably, using a technique for de novo chromosome assembly, we demonstrate that both SMC3 and hRAD21 are recruited to single, unreplicated lampbrush chromatids. Finally, we used our novel method of analyzing the oocyte nucleus under oil combined with fluorescence recovery after photobleaching, to provide direct evidence that cohesin is highly dynamic at discrete, condensed chromosomal regions. Collectively, these data demonstrate that lampbrush chromosomes provide a unique and powerful tool for combining biochemical and cytological analyses for dissection of complex chromosomal processes.     

染色体结构维持蛋白4在胰腺癌中表达的临床与生物信息学分析

目的 研究染色体结构维持蛋白4(structural maintenance of chromosome 4,SMC4)在胰腺癌组织中的表达差异及其与临床病理特征和预后的关系,并探讨其可能发生相互作用的蛋白网络及调控的可能信号通路.方法 采用Western blotting检测中国人民解放军中部战区总医院收集的12例胰...     

Differential effect of simvastatin on activation of Rac(1) vs. activation of the heat shock protein 27-mediated pathway upon oxidative stress,in human smooth muscle cells

In the present study, we have analyzed the response of human smooth muscle cell (SMC)s to oxidative stress, in terms of recruitment of key elements of the stress-activated protein kinase (SAPK) pathway, such as Rac(1), p38, and the small heat shock protein (HSP)27. The level of expression of three small HSPs, alphaB-crystallin, HSP20, HSP27, as well as the phosphorylation levels of HSP27 and p38, were higher in cultured, asynchronously growing SMCs originating from left interior mammary artery (LIMA) than those originating from aorta, saphenous vein, and umbilical vein, validating the choice of SMCs from LIMA as a model system in our study. In synchronized, quiescent SMCs from LIMA, oxidative stress (H(2)O(2) stimulation)-induced membrane translocation of Rac(1), p38 phosphorylation, membrane translocation, and phosphorylation of HSP27. In these cells, simvastatin (S), an HMG-CoA reductase inhibitor, blocked, in a mevalonate-dependent way, oxidative stress-induced membrane translocation of Rac(1). However, S pretreatment prior to oxidative stress increased the levels of p38 phosphorylation, HSP27 membrane translocation/phosphorylation, actin polymerization, and apoptosis in these cells, in a mevalonate-dependent way. These results establish that S pretreatment has a stimulatory effect on the stress-activated p38/HSP27 pathway, despite its blocking effect on Rac(1) activation.     

辛开苦降法对FD大鼠血浆MTL、胃体MTL、ICC及SMC影响的实验研究

Cajal间质细胞(interstitial cells of Cajal,ICC)是胃肠运动的起搏细胞,神经元细胞接受中枢神经系统的信号后传递给ICC,再作用于平滑肌细胞(SMC),从而维持正常的胃肠运动.胃动素(MTL)是目前公认启动胃肠收缩活动的兴奋性脑肠肽,神经冲动传至ICC后可作用于兴奋性神经元产生兴奋性连接电位(excitory junction potential,EJP),使平滑肌细胞产生去极化[1-2].     

Inflammatory mediators mediate airway smooth muscle contraction through a G protein-coupled receptor–transmembrane protein 16A–voltage-dependent Ca2+ channel axis and contribute to bronchial hyperresponsiveness in asthma

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