器官的构造是如何形成的——以果蝇翅为例

在器官发育过程中,细胞是如何接收到指令,在特定的位置形成特定的细胞形貌,来组建一个正确的三维构造实现器官的功能,这是生物学中的最基本问题之一。在发育的早期,选择者基因通过赋予细胞以不同的亲和性把组织划分为若干个隔间区域。隔间边界细胞作为组织者通过分泌信号分子(器官成形素)来促进细胞的存活和增殖,控制细胞的分化和命运,以及确保正确的细胞形貌发生。器官成形素的空间时序性表达以及随后细胞对这些信号分子的反应是正确形成组织构造的关键环节。根据国际最新的研究进展,本文综述了构造形成的机制和主流假说,并以果蝇翅的发育为例,讨论了TGF-β家族器官成形素Dpp在翅发育中的作用机制。     

IL—18信号转导途径研究进展

白细胞介素１８（ＩＬ－１８）是新近发现的细胞因子,其独特的少ＴＡＴＡ型启动子、特殊的ｍＲＮＡ结构及其前体蛋白需ＩＬ－１β转化酶（ＩＣＥ）加工成熟的特点,便得ＩＬ－１８基因可广泛表达于多种类型的细胞,ＩＬ－１８ＩＬ－１８受体结合组成受体复合物,受体复合物信号通过ＩＲＡＫ－ＴＲＡＦ６途径激活ＮＦ－кＢ,及通过酪氨酸蛋白激酶（ＰＴＫ）的ＬＣＫ－ＭＡＰＫ信号途径诱导ＴＨ１细胞产生ＩＦＮ－γ、ＩＬ－２等细胞     

昆虫蜕皮激素信号转导途径研究进展

蜕皮与变态是全变态昆虫典型的发育特征。调控昆虫蜕皮与变态的激素主要有蜕皮激素和保幼激素。目前已经阐明了蜕皮激素的核受体EcR及部分核信号转导途径,但蜕皮激素是否存在膜受体及膜信号转导途径研究很少。研究证明,蜕皮激素存在细胞质中的信号转导分子和途径,蜕皮激素通过NTF2和Ran调控EcR入核启动基因转录。蜕皮激素使细胞质中的热休克蛋白Hsc70部分入核与USP结合启动基因转录。蜕皮激素通过蛋白激酶PKC使伴侣蛋白calponin磷酸化,参与蜕皮激素信号途径的基因转录。这些研究结果说明蜕皮激素除了有核受体和核受体信号转导途径外,还存在细胞膜受体和细胞膜信号转导途径。     

MAPK级联途径在植物信号转导中的研究进展

促分裂原活化蛋白激酶(mitogen-activated protein kinase,MAPK)在植物的胁迫反应应答方面占有重要地位.本文就MAPK的基本组成、分类、激发子和两种可能的机理的最新进展作了综述.并介绍了近年来此领域中的研究方法,包括MAPK活性测定的方法、免疫沉淀法、酵母双杂交、基因突变、RNA干涉和网络模式法.     

果蝇MicroRNA研究进展

MicroRNA(miRNA)是一类大小约20~24个碱基的单链小分子非编码RNA,能够通过与靶mRNA特异性的碱基互补配对,引起靶mRNA的降解或者抑制其翻译,从而对基因进行转录后表达调控。miRNA广泛存在于动物、植物、细菌、病毒等多种生物物种中,并参与了发育调控、细胞凋亡、肿瘤发生、病原体感染等多种生物学进程。近年来对果蝇miRNA进行了鉴定与深入研究,miRNA几乎参与了果蝇生命过程中的所有重要环节,本文对果蝇miRNA的结构、作用机制及其生物学功能等研究进展进行了综述。     

MAPK 级联途径在植物信号转导中的研究进展

促分裂原活化蛋白激酶(mitogen-activated protein kinase, MAPK)在植物的胁迫反应应答方面占有重要地位。本文就MAPK的基本组成、分类、激发子和两种可能的机理的最新进展作了综述。并介绍了近年来此领域中的研究方法,包括MAPK活性测定的方法、免疫沉淀法、酵母双杂交、基因突变、RNA干涉和网络模式法。     

植物激素脱落酸受体及其信号转导途径研究进展

脱落酸是广泛存在于植物体的多功能激素,通过与体内受体及随后的复杂信号网络互作进而调节植物生长发育、抵御环境胁迫。脱落酸受体的筛选和鉴定一直备受关注,并已取得较大突破,其信号转导机制也再次成为人们研究的热点。对脱落酸受体的鉴定以及介导的信号转导途径方面最新进展进行了综述并展望,以期对相关研究领域提供参考。     

Toll样受体信号转导途径研究进展

Toll样受体(Toll-like receptors,TLRs)属于模式识别受体(pattern recognition receptors,PRRs)家族,识别高度保守的微生物组分-病原相关分子模式(pathogen-associated molecular pat-terns,PAMPS)。迄今为止,在人类基因组中已发现10个Toll样受体。这些受体通过感知不同的微生物刺激,招募特异接头蛋白,激活一系列信号级联反应,引发针对病原体的特异性免疫应答,是连接天然免疫和适应性免疫应答的桥梁。哺乳动物Toll样受体的发现引领天然免疫的研究进入飞速发展的时代。本文将对Toll样受体信号转导途径的最新进展作一综述,以便更好地理解Toll样受体介导的分子免疫机制,这将有助于研发免疫治疗的分子靶标,最终有效预防、控制Toll样受体介导的疾病。     

p75受体信号转导途径的研究进展

神经生长因子 (ｎｅｒｖｅｇｒｏｗｔｈｆａｃｔｏｒ,ＮＧＦ)通过与两种受体结合而发挥作用。一种是高亲和性受体ＴｒｋＡ受体 ,它是由原癌基因Ｔｒｋ编码的蛋白质酪氨酸激酶 ;另一种是低亲和性受体ｐ75,它以相同的亲和力与神经营养素 (ｎｅｕｒｏｔｒｏｐｈｉｎ ,ＮＴ)家族的各成员结合 ,因此被称为神经营养素受体ｐ75(ｐ75ＮＴＲ)。ＮＧＦ与ＴｒｋＡ受体结合后发挥其促进神经细胞生长和存活的作用 ,而近年来发现ｐ75受体在特定条件下却能够诱导某些神经细胞和胶质细胞的凋亡 ,由于ｐ75ＮＴＲ的这一作用 ,它受到越来越多的关注。1 .ｐ75Ｎ…     

脱落酸信号转导研究进展

对脱落酸受体、脱落酸调控基因表达、脱落酸信号调节分子以及保卫细胞中脱落酸信号调控的最新研究进展进行了综述.     

Signaling pathways directing the movement and fusion of epithelial sheets: lessons from dorsal closure in Drosophila

Wound healing in embryos and various developmental events in metazoans require the spreading and fusion of epithelial sheets. The complex signaling pathways regulating these processes are being pieced together through genetic, cell biological, and biochemical approaches. At present, dorsal closure of the Drosophila embryo is the best-characterized example of epithelial sheet movement. Dorsal closure involves migration of the lateral epidermal flanks to close a hole in the dorsal epidermis occupied by an epithelium called the amnioserosa. Detailed genetic studies have revealed a network of interacting signaling molecules regulating this process. At the center of this network is a Jun N-terminal kinase cascade acting at the leading edge of the migrating epidermis that triggers signaling by the TGF-beta superfamily member Decapentaplegic and which interacts with the Wingless pathway. These signaling modules regulate the cytoskeletal reorganization and cell shape change necessary to drive dorsal closure. Activation of this network requires signals from the amnioserosa and input from a variety of proteins at cell-cell junctions. The Rho family of small GTPases is also instrumental, both in activation of signaling and regulation of the cytoskeleton. Many of the proteins regulating dorsal closure have been implicated in epithelial movement in other organisms, and dorsal closure has emerged as an ideal model system for the study of the migration and fusion of epithelial sheets.     

Dorsal closure in Drosophila: cells cannot get out of the tight spot

Dorsal closure (DC), the closure of a hole in the dorsal epidermis of Drosophila embryos by the joining of opposing epithelial cell sheets, has been used as a model process to study the molecular and cellular mechanisms underlying epithelial spreading and wound healing. Recent studies have provided novel insights into how different tissues function cooperatively in this process. Specifically, they demonstrate a critical function of the epidermis surrounding the hole in modulating the behavior of the amnioserosa cells inside. These findings shed light not only on the mechanisms by which the behavior of different tissues is coordinated during DC, but also on the general mechanisms by which tissues interact to trigger global morphogenesis, an essential but yet poorly explored aspect of embryogenesis.     

p38 MAPK信号传导通路

丝裂原活化蛋白激酶（ｍｉｔｏｇｅｎ－ａｃｔｉｖａｔｅｄｐｏｒｏｔｅｉｎｋｉｎａｓｅ,ＭＡＰＫ）介导了生长、发育,分裂,死亡,以及细胞间的功能同步等多种细胞生理功能,在哺乳动物细胞中已发现和克隆了ＥＲＫ、ＪＮＫ／ＳＡＰＫ,ＥＲＫ５／ＢＭＫ１和ｐ３８／ＲＫ四个ＭＡＰＫ亚族,这些新的ＭＡＰＫ介导了物理,化学反激,细菌产物,炎性细胞因子等多种刺激引起的细胞反应,ｐ３８亚族至少包括ｐ３８（α）,ｐ３８β,ｐ     

bFGF信号传导及其与肿瘤关系的新进展

碱性成纤维细胞生长凶子(bFGF)是FGF家族的重要成员,具有促细胞增殖、分化、迁移、凋亡等多种功能,并与肿瘤病理存在一定相关性。bFGF生物学作用的多效性,来源十其信号传导途径的复杂性。本文简要介绍近年来bFGF信号传导中bFGF亚型、HSPG、FGFR和其他调控蛋白等研究的新进展,并浅析其与肿瘤生长、血管生成、肿瘤抑制及抑制分子机制等方面的关系。     

Contrasting selection pressures on components of the Ras-mediated signal transduction pathway in Drosophila

The molecular genetics of several signal transduction pathways is well characterized, providing an opportunity to address the nature of the population genetic forces acting on functionally related suites of pleiotropic regulatory genes. Signal transduction is the process by which signals are transmitted from the cell surface to the nucleus or other cellular structures. It plays a fundamental role in regulating a wide range of developmental and physiological processes, many of which are likely to be subject to buffering mechanisms. Here we infer that contrasting selection pressures act on six components of the Ras signal transduction pathway by comparing sequences obtained from 25 alleles of Drosophila melanogaster with one allele of the sibling species D. simulans. The three most upstream components of the cascade, Ras, Drk and polehole, experience strong purifying selection, as they show no fixed amino acid differences between the species and just a handful of rare replacement polymorphisms within D. melanogaster. This portion of the pathway is likely to act as a control point in signal transduction, because the more downstream components Dsor1, corkscrew and Ksr, each show several amino acid replacements between the species. Furthermore, Ksr is nearly monomorphic within D. melanogaster, and application of the HKA and McDonald and Kreitman tests indicate that this gene may have experienced a recent selective sweep, suggesting that modifiers of Ras kinase signalling are the most likely source of quantitative variation associated with this core regulatory pathway.     

Engineering key components in a synthetic eukaryotic signal transduction pathway

Signal transduction underlies how living organisms detect and respond to stimuli. A goal of synthetic biology is to rewire natural signal transduction systems. Bacteria, yeast, and plants sense environmental aspects through conserved histidine kinase (HK) signal transduction systems. HK protein components are typically comprised of multiple, relatively modular, and conserved domains. Phosphate transfer between these components may exhibit considerable cross talk between the otherwise apparently linear pathways, thereby establishing networks that integrate multiple signals. We show that sequence conservation and cross talk can extend across kingdoms and can be exploited to produce a synthetic plant signal transduction system. In response to HK cross talk, heterologously expressed bacterial response regulators, PhoB and OmpR, translocate to the nucleus on HK activation. Using this discovery, combined with modification of PhoB (PhoB‐VP64), we produced a key component of a eukaryotic synthetic signal transduction pathway. In response to exogenous cytokinin, PhoB‐VP64 translocates to the nucleus, binds a synthetic PlantPho promoter, and activates gene expression. These results show that conserved‐signaling components can be used across kingdoms and adapted to produce synthetic eukaryotic signal transduction pathways.     

Characterization of changes of pain behavior and signal transduction system in food-deprived mice

Fasting in general causes several metabolic changes. In the present study, we examined the possible changes of several types of nociception during the food deprivation were investigated in mice. After the mice were forced into the fasting for 12, 24, or 48?h, the changes of nociception were measured by the tail-flick, writhing, formalin or von-frey tests. We found that the nociceptive behavior induced by intraperitoneally (i.p.) administered acetic acid (writhing response) or intraplantar injection of 5% formalin into the hind-paw were reduced in fasted group. In addition, the tail-flick response and threshold for nociception in mechanical von-frey test were also elevated in fasted group. Moreover, the p-CREB and p-ERK levels in the dorsal root ganglia (DRG) and the spinal cord were reduced in food-deprived group. Furthermore, p-AMPKα₁ expressions in DRG and the spinal cord were up-regulated, whereas p-mTOR in DRG and the spinal cord was down-regulated in food-deprived group. Our results suggest that the chemical, mechanical, and thermal nociceptions appear to be reduced in a food-deprived mouse group. Additionally, reduction of nociception in food-deprived group appears to be closely associated with the expressions of several signal transduction molecules such as ERK, CREB, AMPKα₁ and mTOR proteins in DRG and the spinal cord.     

油菜内酯类似物(BRs)的生物合成与信号传导引起的植物矮化

植物体内的BRs生物合成突变或者感受BRs失调导致植物矮化。本文介绍了BRs的生物合成途径和感受途径相关的基因及其突变型,从分子水平上阐述了这些矮化类型与BRs的关系,并就BRs促进细胞伸长的机制作了一些探讨。     

Specialized extraembryonic cells connect embryonic and extraembryonic epidermis in response to Dpp during dorsal closure in Drosophila

Dorsal closure in Drosophila embryogenesis involves expansion of the dorsal epidermis, followed by closure of the opposite epidermal edges. This process is driven by contractile force generated by an extraembryonic epithelium covering the yolk syncytium known as the amnioserosa. The secreted signaling molecule Dpp is expressed in the leading edge of the dorsal epidermis and is essential for dorsal closure. We found that the outermost row of amnioserosa cells (termed pAS) maintains a tight basolateral cell-cell adhesion interface with the leading edge of dorsal epidermis throughout the dorsal closure process. pAS was subject to altered cell motility in response to Dpp emanating from the dorsal epidermis, and this response was essential for dorsal closure. alphaPS3 and betaPS integrin subunits accumulated in the interface between pAS and dorsal epidermis, and were both required for dorsal closure. Looking at alphaPS3, type I Dpp receptor, and JNK mutants, we found that pAS cell motility was altered and pAS and dorsal epidermis adhesion failed under the mechanical stress of dorsal closure, suggesting that a Dpp-mediated mechanism connects the squamous pAS to the columnar dorsal epidermis to form a single coherent epithelial layer.