RNA干涉与基因沉默研究进展

生物体内导入双链RNA(dsRNA)后会引起体内同源基因特异的沉默，这种现象称为RNA干涉(RNAi)．基因沉默是生物体基因表达调控的一种重要机制，具有重要生物学功能．就RNA干涉与基因沉默的研究历史、作用机制和应用作了综述．     

生物序列数据挖掘技术研究

生物序列数据是生物信息数据中重要的一部分,研究生物序列解读其隐含的生物学意义是生物信息学研究的热点和难点。数据挖掘是当前分析大规模数据的有效工具之一,已广泛应用于分析生物序列数据,并取得了许多研究成果。文章综述了生物序列数据挖掘的关键技术,包括序列比对算法、DNA序列模式挖掘、关联、分类、聚类分析、RNA二级结构预测、蛋白质序列分类和聚类分析,最后展望未来研究方向。     

RNAi在植物中的作用机理及其应用研究进展

本文综述了近年来有关RNA干扰的发现、作用过程及其作用机理,并介绍了RNA干扰在植物基因功能、植物抗病毒、作物品种改良等方面的应用.     

哺乳动物谷胱甘肽转移酶研究进展

谷胱甘肽转移酶(谷胱甘肽硫转移酶)(GSTs)是一类广泛分布于微生物、植物、昆虫、鱼以及哺乳动物,在诸多生物学过程中发挥重要作用的蛋白超家族,具有解毒和清除过氧化物双重功能.近年来,国内外研究人员进一步对GST在生物化学、结构生物学、分子生物学、进化生物学以及基因组学等层面进行了大量的分析和研究.本文将针对有关GST的研究展开综述,以期为深入开展哺乳动物GST基因适应和进化研究提供借鉴.     

萜类微生物生物合成研究进展

萜类是一类具有重要研究及药用价值的天然化合物.近年来,随着萜类合成途径中各种关键酶基因克隆、异源表达和功能鉴定,许多萜类生物合成途径逐渐清晰.以萜类微生物生物合成过程中的中间产物为线索,综述了应用代谢工程、合成生物学、系统生物学等技术开展的萜类微生物生物合成的研究进展.     

秀丽线虫细胞核内小干扰RNA调控基因表达的机制研究

生物体内存在大量的不编码蛋白质序列的非编码RNA(noncoding RNA,ncRNA),这些非编码RNA广泛参与生命活动的各个过程,包括基因表达调控、基因组稳定性维持、抵抗外源核酸侵染、发育的时序调节以及肿瘤发生等.越来越多的证据表明一系列重大疾病的发生、发展与这些非编码RNA的产生和调控失衡相关.小调节性RNA正在成为潜在的疾病标志物、药物靶点和生物分子药物.我们的研究主要集中在高等多细胞生物中细胞核里小干扰RNA调控基因表达的分子机制和生物学功能.我们在模式生物秀丽线虫中通过遗传筛选的方法发现了一条小干扰RNA在细胞核内调控基因表达的通路,以及参与这条通路的几个关键的细胞核RNA干扰缺陷型基因(nuclear RNAi defective,Nrde).这一发现不仅解决了高等多细胞生物中细胞核内是否存在小RNA干扰现象的争论,而且发现小RNA可能通过主动转运的方式进入细胞核并调控RNA聚合酶Ⅱ(RNAPⅡ)介导的转录延伸.这一通路还可能参与了生物体的获得性遗传过程.本文重点阐述这一小干扰RNA调控基因表达的分子机制,并提出未来亟待解决的科学问题和发展方向.     

动物MicroRNAs的研究进展

MicroRNAs（miRNAs）是一类小的、内源的、非编码的RNA家族,其在转录后水平上对基因表达进行调控。nfiRNAs是在研究秀丽新小杆线虫（Caenorhabditis elegans）发育转变过程中发现的,最初称为stRNAs（small temporal RNA,小时序RNA）,但stRNAs只是miRNAs家族的一部分,随后在线虫、植物和哺乳动物中发现了miRNAs家族的数百个成员。动物miRNAs不仅在发育调控中起重要作用,还参与许多重要的生理过程。本文综述了动物中miRNAs的发现历程、生物学起源、作用机制、生物学功能、研究方法,并对动植物miRNAs的特点进行了比较。     

胶原蛋白研究进展

胶原蛋白以其独特的生物特性而具有广阔的应用前景.对近年来国内外学者与生产厂家对胶原蛋白的制备、生物学功能作用及应用方面的研究进展进行了综述,以期充分有效地利用该生物资源.     

原子力显微镜在癌细胞观察和研究中的应用

原子力显微镜(AFM),能够在接近生理条件下以具有原子级的分辨率对活细胞进行表面成像和超微结构观察,同时可以研究细胞的生物过程、细胞与药物之间和细胞之间的相互作用,成为细胞生物学研究的一种有效工具.近年来AFM在细胞生物学研究中的应用进展很快,许多研究成果在生物医学和临床医学方面有良好的应用前景.本文分析了原子力显微镜的成像机理、工作模式和技术要点,综述了原子力显微镜在癌细胞的研究应用现状和前景.     

RNA干扰技术的研究进展

RNA干扰是指由外源双链RNA与其细胞内同源mRNA特异结合引起基因沉默现象,广泛存在于动、植物等各种生物体内,是目前分子生物学领域研究的热点之一。我们简要综述了RNA干扰发生的机制、特点以及RNA干扰的应用等。     

The functions of animal microRNAs

MicroRNAs (miRNAs) are small RNAs that regulate the expression of complementary messenger RNAs. Hundreds of miRNA genes have been found in diverse animals, and many of these are phylogenetically conserved. With miRNA roles identified in developmental timing, cell death, cell proliferation, haematopoiesis and patterning of the nervous system, evidence is mounting that animal miRNAs are more numerous, and their regulatory impact more pervasive, than was previously suspected.     

A germline-specific class of small RNAs binds mammalian Piwi proteins

Small RNAs associate with Argonaute proteins and serve as sequence-specific guides to regulate messenger RNA stability, protein synthesis, chromatin organization and genome structure. In animals, Argonaute proteins segregate into two subfamilies. The Argonaute subfamily acts in RNA interference and in microRNA-mediated gene regulation using 21-22-nucleotide RNAs as guides. The Piwi subfamily is involved in germline-specific events such as germline stem cell maintenance and meiosis. However, neither the biochemical function of Piwi proteins nor the nature of their small RNA guides is known. Here we show that MIWI, a murine Piwi protein, binds a previously uncharacterized class of approximately 29-30-nucleotide RNAs that are highly abundant in testes. We have therefore named these Piwi-interacting RNAs (piRNAs). piRNAs show distinctive localization patterns in the genome, being predominantly grouped into 20-90-kilobase clusters, wherein long stretches of small RNAs are derived from only one strand. Similar piRNAs are also found in human and rat, with major clusters occurring in syntenic locations. Although their function must still be resolved, the abundance of piRNAs in germline cells and the male sterility of Miwi mutants suggest a role in gametogenesis.     

Intravenous delivery of a multi-mechanistic cancer-targeted oncolytic poxvirus in humans

The efficacy and safety of biological molecules in cancer therapy, such as peptides and small interfering RNAs (siRNAs), could be markedly increased if high concentrations could be achieved and amplified selectively in tumour tissues versus normal tissues after intravenous administration. This has not been achievable so far in humans. We hypothesized that a poxvirus, which evolved for blood-borne systemic spread in mammals, could be engineered for cancer-selective replication and used as a vehicle for the intravenous delivery and expression of transgenes in tumours. JX-594 is an oncolytic poxvirus engineered for replication, transgene expression and amplification in cancer cells harbouring activation of the epidermal growth factor receptor (EGFR)/Ras pathway, followed by cell lysis and anticancer immunity. Here we show in a clinical trial that JX-594 selectively infects, replicates and expresses transgene products in cancer tissue after intravenous infusion, in a dose-related fashion. Normal tissues were not affected clinically. This platform technology opens up the possibility of multifunctional products that selectively express high concentrations of several complementary therapeutic and imaging molecules in metastatic solid tumours in humans.     

Site-specific DICER and DROSHA RNA products control the DNA-damage response

Non-coding RNAs (ncRNAs) are involved in an increasingly recognized number of cellular events. Some ncRNAs are processed by DICER and DROSHA RNases to give rise to small double-stranded RNAs involved in RNA interference (RNAi). The DNA-damage response (DDR) is a signalling pathway that originates from a DNA lesion and arrests cell proliferation3. So far, DICER and DROSHA RNA products have not been reported to control DDR activation. Here we show, in human, mouse and zebrafish, that DICER and DROSHA, but not downstream elements of the RNAi pathway, are necessary to activate the DDR upon exogenous DNA damage and oncogene-induced genotoxic stress, as studied by DDR foci formation and by checkpoint assays. DDR foci are sensitive to RNase A treatment, and DICER- and DROSHA-dependent RNA products are required to restore DDR foci in RNase-A-treated cells. Through RNA deep sequencing and the study of DDR activation at a single inducible DNA double-strand break, we demonstrate that DDR foci formation requires site-specific DICER- and DROSHA-dependent small RNAs, named DDRNAs, which act in a MRE11–RAD50–NBS1-complex-dependent manner (MRE11 also known as MRE11A; NBS1 also known as NBN). DDRNAs, either chemically synthesized or in vitro generated by DICER cleavage, are sufficient to restore the DDR in RNase-A-treated cells, also in the absence of other cellular RNAs. Our results describe an unanticipated direct role of a novel class of ncRNAs in the control of DDR activation at sites of DNA damage.     

A resource for large-scale RNA-interference-based screens in mammals

Gene silencing by RNA interference (RNAi) in mammalian cells using small interfering RNAs (siRNAs) and short hairpin RNAs (shRNAs) has become a valuable genetic tool. Here, we report the construction and application of a shRNA expression library targeting 9,610 human and 5,563 mouse genes. This library is presently composed of about 28,000 sequence-verified shRNA expression cassettes contained within multi-functional vectors, which permit shRNA cassettes to be packaged in retroviruses, tracked in mixed cell populations by means of DNA 'bar codes', and shuttled to customized vectors by bacterial mating. In order to validate the library, we used a genetic screen designed to report defects in human proteasome function. Our results suggest that our large-scale RNAi library can be used in specific, genetic applications in mammals, and will become a valuable resource for gene analysis and discovery.