乙酰胆碱结合蛋白的特点及应用

乙酰胆碱结合蛋白(acetylcholine-binding proteins,AChBPs)的基本特征、结构特点和激活机制与烟碱型乙酰胆碱受体(the nicotinic acetylcholine recepror,nAChRs)相似.通过对AChBPs晶体结构与功能的研究,能准确阐明nAChRs结构与功能的关系.通过对配体和AChBPs的复合物的晶体结构解析,有助于我们理解配体与nAChRs相互作用的机理,为开发治疗疼痛、成瘾、帕金森症、阿尔茨海默氏症和癫痫等疾病的新药提供理论基础.     

斑鳜肌球蛋白轻链2基因cDNA的克隆及其纵向表达分析

从斑鳜(Siniperca scherzeri)背部白色肌肉组织中提取总RNA,利用RT-PCR法克隆到斑鳜肌球蛋白轻链2基因(MLC2)(GenBank:GQ283000).斑鳜MLC2基因cDNA序列的开放阅读框的长度为513 bp,编码170个氨基酸,理论相对分子质量为19 105.61 Da,等电点为4.73.该开放阅读框具有4个EF-手相结构.斑鳜MLC2推导的氨基酸序列与已报道的其它6种鱼类MLC2氨基酸序列同源性在89%以上,其中与Ca2+结合的区域非常保守,氨基酸序列同源性为100%.用实时荧光定量PCR对斑鳜MLC2纵向表达分析显示,MLC2在斑鳜背肌的前部、中部和后部都有表达,但无显著差异.     

小清蛋白研究进展

小清蛋白作为维持细胞内钙离子交换的钙结合蛋白,是脊椎动物体内肌浆蛋白的主要组成部分,在调节细胞内钙离子交换中起重要作用。我们简要综述了小清蛋白的分布、分类、结构和作用机理等,重点介绍小清蛋白在鱼肌肉运动、系统发育和神经组织中的作用以及由小清蛋白引起的过敏反应。     

Down-Regulation of miR-126 Is Associated with Colorectal Cancer Cells Proliferation,Migration and Invasion by Targeting IRS-1 via the AKT and ERK1/2 Signaling Pathways

Background

Colorectal carcinoma (CRC) is one of the leading causes of cancer-related mortality worldwide. MicroRNAs (miRNAs, miRs) play important roles in carcinogenesis. MiR-126 has been shown to be down-regulated in CRC. In this study, we identified the potential effects of miR-126 on some important biological properties of CRC cells and clarified the regulation of insulin receptor substrate 1 (IRS-1) and its possible signaling pathway by miR-126.

Methods

The effect of miR-126 on IRS-1, AKT, and ERK1/2 expression was assessed in the CRC cell lines HT-29 and HCT-116 with a miR-126 mimic or inhibitor to increase or decrease miR-126 expression. Furthermore, the roles of miR-126 in regulation of the biological properties of CRC cells were analyzed with miR-126 mimic or inhibitor-transfected cells. The 3′-untranslated region (3′-UTR) of IRS-1 regulated by miR-126 was analyzed by using a dual-luciferase reporter assay.

Results

We found that IRS-1 is the functional downstream target of miR-126 by directly targeting the 3′-UTR of IRS-1. Endogenous miR-126 and exogenous miR-126 mimic inhibited IRS-1 expression. Furthermore, gain-of-function or loss-of-function studies showed that over-expression of miR-126 down-regulated IRS-1, suppressed AKT and ERK1/2 activation, CRC cells proliferation, migration, invasion, and caused cell cycle arrest, but had no effect on cell apoptosis. Knockdown of miR-126 promoted these processes in HCT-116 cells and promoted AKT and ERK1/2 activation by up-regulating the expression of the IRS-1 protein.

Conclusions

MiR-126 may play roles in regulation of the biological behavior of CRC cells, at least in part, by targeting IRS-1 via AKT and ERK1/2 signaling pathways.     

淀粉蔗糖酶AcAS的工作机理与去折叠性质研究

淀粉蔗糖酶(amylosucrase, AS)是一种葡萄糖基转移酶(E.C. 2.4.1.4),隶属于糖苷水解酶13家族．当体系中存在葡聚糖时,AS可以蔗糖为唯一底物催化合成直链葡聚糖．与AS相比,其他拥有合成直链淀粉样多糖的酶都需要利用昂贵的核苷酸激活糖来进行合成．这使得AS成为一种具有工业应用潜力的工业酶．尽管具有较大应用潜力,但是较弱的稳定性严重影响其在工业上的应用．本工作中,以NpAS和DgAS的晶体结构为模板,对氯酚节杆菌(Arthrobacter chlorophenolicus)中发现的一种新型AS(AcAS)结构进行了模建．通过对AcAS与其他AS结构进行详细的比较,推断出AcAS的工作机理．随后,利用高斯网络模型(GNM)对其功能型运动进行了分析．根据GNM的结果,发现AcAS可分为两个运动方向相异的部分．最后,利用迭代高斯网络对AcAS的去折叠性质进行了研究．这些结果对随后的淀粉蔗糖酶的工业开发有一定帮助．     

Wind conditions affect stopover decisions and fuel stores of shorebirds migrating through the south Yellow Sea

We assessed the effects of wind conditions on stopover decisions and fuel stores of migratory shorebirds at Chongming Dongtan in the south Yellow Sea along the East Asian–Australasian Flyway. In spring and autumn, wind directions differed among altitudes and wind speed generally increased with altitude. Numbers of shorebirds were related to wind effects at low altitudes (on the ground and at 300 and 800 m above the ground), wind effects at 300 m being the best predictor of shorebird numbers. In spring, total number of shorebirds and numbers of the four most abundant shorebird species were negatively related to wind assistance at low altitudes, more birds departing when tailwinds prevailed and more arriving when headwinds prevailed. In autumn, however, total number of shorebirds and numbers of the four most abundant species were positively related to wind assistance at low altitudes, more birds departing and more arriving with tailwinds than with headwinds. When tailwinds prevailed, the number of arriving birds was higher than the number of departing birds. The fuel stores of captured shorebirds, represented by their body mass, was related to wind effects and change in wind conditions between two consecutive days in both spring and autumn, captured birds being heavier when headwinds prevailed than in tailwind conditions, and when the wind conditions became less favourable for flight between two consecutive days. Our results suggest that wind conditions affect stopover decisions and fuel stores, and thus the optimal migration and fuel deposition strategies of migratory shorebirds.     

Mesenchymal stem cell–derived extracellular vesicles: a new impetus of promoting angiogenesis in tissue regeneration

Over the past few decades, extracellular vesicles (EVs) have emerged as crucial mediators of intercellular communication. EVs encapsulate and convey information to surrounding cells or distant cells, where they mediate cellular biological responses. Among their multifaceted roles in the modulation of biological responses, the involvement of EVs in vascular development, growth and maturation has been widely documented and their potential therapeutic application in regenerative medicine or in the treatment of angiogenesis-related diseases is drawing increasing interest. In this review, we have summarized the details about the current knowledge on biogenesis of EVs and conventional isolation methods. Evidence supporting the use of EVs derived from mesenchymal stromal cells (MSCs) to enhance angiogenesis in the development of insufficient angiogenesis, such as chronic wounds, stroke and myocardial infarction, will also be discussed critically. Finally, the main challenges and prerequisites for their therapeutic applications will be evaluated.