Eph-ephrin介导反向信号传递的研究进展

双向信号传递是细胞间通讯领域中新近阐明的机制,酪氨酸激酶受体-配体(Eph-ephrin)介导的双向信号传递是此机制中的一个重要代表.Eph酪氨酸激酶家族受体及其配体ephrin家族成员是在神经发育、血管新生等方面起重要作用的分子,通过Eph向细胞内传递的信号称为正向信号,通过其配体ephrin的信号称为反向信号.Ephrin家族又可根据分子结构分为2个亚家族,其中ephrinB为跨膜蛋白,可通过酪氨酸磷酸化依赖和PDZ结合结构域介导2种方式向胞内传递反向信号,活化FAK、JNK、Wnt等信号通路,ephrinA为糖基磷脂酰肌醇锚定蛋白,也具有反向信号传递功能.     

The membrane and lipids as integral participants in signal transduction: lipid signal transduction for the non-lipid biochemist

Reviews of signal transduction have often focused on the cascades of protein kinases and protein phosphatases and their cytoplasmic substrates that become activated in response to extracellular signals. Lipids, lipid kinases, and lipid phosphatases have not received the same amount of attention as proteins in studies of signal transduction. However, lipids serve a variety of roles in signal transduction. They act as ligands that activate signal transduction pathways as well as mediators of signaling pathways, and lipids are the substrates of lipid kinases and lipid phosphatases. Cell membranes are the source of the lipids involved in signal transduction, but membranes also constitute lipid barriers that must be traversed by signal transduction pathways. The purpose of this review is to explore the magnitude and diversity of the roles of the cell membrane and lipids in signal transduction and to highlight the interrelatedness of families of lipid mediators in signal transduction.     

Concentrations of signal transduction proteins exercise and insulin responses in rat extensor digitorum longus and soleus muscles

Differences in the concentrations of signal transduction proteins often alter cellular function and phenotype, as is evident from numerous, heterozygous knockout mouse models for signal transduction proteins. Here, we measured signal transduction proteins involved in the adaptation to exercise and insulin signalling in fast rat extensor digitorum longus (EDL; 3% type I fibres) and the slow soleus muscles (84% type I fibres). The EDL and soleus were excised from four rats, the proteins extracted and subjected to Western blots for various signal transduction proteins. Our results show major differences in signal transduction protein concentrations between EDL and soleus. The EDL to soleus concentration ratios were: Calcineurin: 1.43 +/- 0.10; ERK1: 0.38 +/- 0.18; ERK2: 0.61 +/- 0.16; p38alpha, beta: 1.36 +/- 0.15; p38gamma/ERK6: 0.95 +/- 0.11; PKB/AKT: 1.44 +/- 0.08; p70S6k: 6.86 +/- 3.58; GSK3beta: 0.69 +/- 0.03; myostatin: 1.95 +/- 0.43; NF-kappaB: 0.32 +/- 0.10 (values >1 indicate higher expression in the EDL, and values < 1 indicate higher expression in the soleus). With the exception of p38gamma/ERK6, the concentration of each signal transduction protein was uniformly higher in one muscle than in the other in all four animals. These experiments show that signal transduction protein concentrations vary between fast and slow muscles, presumably reflecting a concentration difference on a fibre level. Proteins that promote particular functions such as growth or slow phenotype are not necessarily higher in muscles with that particular trait (e.g. higher in larger fibres or slow muscle). Interindividual differences in fibre composition might explain variable responses to training and insulin.     

Average density and size of microclusters of epidermal growth factor receptors on A431 cells.

For some hormone receptors, the early events of signal transduction depend on their molecular arrangement and interactions at the cell surface. An understanding of the mechanism of signal transduction in general needs a careful analysis of the receptor distribution. Here, we present the first quantitative measurement of epidermal growth factor receptor distribution on A431 cells obtained by scanning fluorescence correlation spectroscopy. Prior to epidermal growth factor binding, the A431 cell membrane presents an average surface density of 7.7-8.4 microclusters/microns 2, each containing an average of 130 receptors.     

Effects of fatty acid nitroalkanes on signal transduction pathways and airway macrophage activation

Fatty acid nitroalkenes are reversibly-reactive electrophiles that are endogenously detectable at nM concentrations and display anti-inflammatory, pro-survival actions. These actions are elicited through the alteration of signal transduction proteins via a Michael addition on nucleophilic cysteine thiols. Nitrated fatty acids (NO₂-FAs), like 9- or 10-nitro-octadec-9-enolic acid, will act on signal transduction proteins directly or on key regulatory proteins to cause an up-regulation or down-regulation of the protein’s expression, yielding an anti-inflammatory response. These responses have been characterized in many organ systems, such as the cardiovascular system, with the pulmonary system less well defined. Macrophages are one of the most abundant immune cells in the lung and are essential in maintaining lung homeostasis. Despite this, macrophages can play a role in both acute and chronic lung injury due to up-regulation of anti-inflammatory signal transduction pathways and down-regulation of pro-inflammatory pathways. Through their propensity to alter signal transduction pathways, NO₂-FAs may be able to reduce macrophage activation during pulmonary injury. This review will focus on the implications of NO₂-FAs on macrophage activation in the lung and the signal transduction pathways that may be altered, leading to reduced pulmonary injury.     

Hindered tomato reproductive development by altered brassinosteroid sensitivity1 mutant

Plant Growth Regulation - The extracellular domain of bri1 perceives brassinosteroids (BRs), and its signal transduction mediates the kinase signal transduction pathway. Disruption in this...     

Endosomes,receptor tyrosine kinase internalization and signal transduction

Upon the binding of insulin or epidermal growth factor to their cognate receptors on the liver parenchymal plasmalemma, signal transduction and receptor internalization are near co-incident. Indeed, the rapidity and extent; of ligand mediated receptor internalization into endosomes in liver as well as other organs predicts that signal transduction is regulated at this intracellular locus. Although internalization has been thought as a mechanism to attenuate ligand mediated signal transduction responses, detailed studies of internalized receptors in isolated liver endosomes suggest an alternative scenario whereby selective signal transduction pathways can be accessed at this locus.     

Platelet GP Ib/IX/V complex: physiological role

Platelets play an essential role in primary hemostasis and in thrombotic events, particularly in arterial vessels, as rheological conditions originate closer interactions between platelets and endothelium than lower shear rates. In response to vascular injury, platelets adhere to the subendothelial matrix by membrane receptors potentiating the generation of thrombin, become activated, and a series of biochemical processes induce platelet aggregation and liberation of intracellular metabolic products to the extracelular medium. Among platelet receptors, glycoprotein (GP) Ib/IX/V complex is peculiar, as it binds adhesive proteins, mainly von Willebrand factor (vWF), and thrombin, the main platelet agonist. Platelet adhesion and subsequent aggregation under conditions of high shear flow, essentially relies upon this receptor's capacity of binding to the subendothelial matrix, initiating signal transduction. Two proteins associated to GP Ib/IX/V, actin-binding protein (ABP) 280 and 14-3-3zeta, are potential mediators of signal transduction by the complex, but their specific contribution in this process is not yet fully understood. Additionally, two proteins implicated in signal transduction by immune stimuli, FcgammaRIIA and FcR gamma-chain, associate with GPIb/IX/V complex, and increasing data indicate a potential role in GPIbalpha mediated signal transduction.     

植物抗逆相关蛋白激酶的结构与功能

植物在遭受外界逆境胁迫时,体内的信号传导系统能够感知、传递逆境胁迫信号,并引起各种生理生化反应以适应环境。植物蛋白激酶在信号感知、传导以及基因的表达调控中起重要的作用。蛋白激酶在信号传导过程的功能是磷酸化修饰目的蛋白,而磷酸化的实现需要蛋白质之间相互作用。本文从植物蛋白激酶的结构、分类、与激素信号传导之间的关系等方面进行了系统的阐述,对蛋白激酶介导的植物抗性与发育的最新研究进展进行了系统的总结,为解析蛋白激酶在植物生长发育中的抗逆机理提供依据。     

我国光形态建成研究回顾

对国内和海外中国科学家在植物光形态建成领域的研究进行了简要的总结和回顾。本文内容包括光敏色素调节的反应及其信号转导,蓝光反应及其信号转导,光周期调节及光形态建成的其他几个方面。     

14-3-3 proteins: regulation of signal-induced events

The field of signal transduction has experienced a significant paradigm shift as a result of an increased understanding of the roles of 14-3-3 proteins. There are many cases where signal-induced phosphorylation itself may cause a change in protein function. This simple modification is, in fact, the primary basis of signal transduction events in many systems. There are a large and growing number of cases, however, where simple phosphorylation is not enough to effect a change in protein function. In these cases, the 14-3-3 proteins can be required to complete the change in function. Therefore signal transduction can be either the relatively simple process where phosphorylation alters target activity, or it can be a more complex, multistep process with the 14-3-3 proteins playing the major role of bringing the signal transduction event to completion. This makes 14-3-3-modulated signal transduction a more complicated process with additional avenues for regulation and variety. Adding further complexity to the process is the fact that 14-3-3 proteins are present as multigene families in most organisms (Aitken et al. Trends Biochem Sci 17: 498–501, 1992; Ferl Annu Rev Plant Physiol Plant Molecular Biology 47: 49–73, 1996), with each member of the family being differentially expressed in various tissues and with potentially differential affinity for various target proteins. This review focuses on the 14-3-3 family of Arabidopsis as a model for further developing understanding of the roles of the 14-3-3 proteins as modulators of signal transduction events in plants. The primary approaches to these questions are not unlike the approaches that would be used in the functional dissection of any multigene family, but the interpretation of these data will have wide implications since the 14-3-3 s physically interact with other protein families.     

Fusicoccin and its receptors

Purified preparations of FC receptors from maize, obtained under non-denaturing conditions, showed in SDS-PAGE two doublets of proteins with an apparent molecular mass of 30 and 90 kDa. In this paper the isolation of the 30 kDa protein, its identification as a 14-3-3-like protein, as well as its immunological detection in partially-purified FC-receptor preparations from bean and spinach are described. The 14-3-3 proteins have biochemical properties consistent with potential signalling roles, and their presence in highly purified FC-receptor preparations suggests that they may be involved in FC- signal transduction. Photoaffinity labelling experiments demonstrating that the protein at 90 kDa binds FC are also presented. The evidence presented taken as a whole, suggests the occurrence in maize of a protein complex for FC perception and signal transduction.     

Lipids and signal transduction in the nucleus.

During the last few years a growing amount of data has accumulated showing phospholipid participation in nuclear signal transduction. Very recent data strongly support the hypothesis that signal transduction in the nucleus is autonomic. Local production of inositol polyphosphates, beginning with the activation of phospholipase C is required for their specific function in the nucleus. Enzymes which modify polyphosphoinositols may control gene expression. Much less information is available about the role of other lipids in nuclear signal transduction. The aim of this minireview is to stress what is currently known about nuclear lipids with respect to nuclear signal transduction.     

我国光形态建成研究回顾

对国内和海外中国科学家在植物光形态建成领域的研究进行了简要的总结和回顾。本文内容包括光敏色素调节的反应及其信号转导,蓝光反应及其信号转导,光周期调节及光形态建成的其他几个方面。     

油菜素甾醇类与生长素的相互作用

油菜素甾醇类(brassinosteroid,BR)和生长素是两类重要的植物激素,二者在许多生理功能上存在相关性。近年来的研究表明,BR与生长素能协同调节基因表达,二者在代谢、运输和信号转导途径等不同层次上存在相互作用,并且这两种信号与其他信号转导途径,如激素信号转导途径和光信号转导途径之间也存在信号对话。现对BR与生长素之间这种复杂的相互作用进行评述。     

14-3-3 proteins,red light and photoperiodic flowering: A point of connection?

The 14-3-3 family of proteins is well known for participating in signal transduction by binding specifically phosphorylated proteins, thereby completing their kinase-induced transition in activity or localization. This interaction-based modulation of signal flux through metabolic pathways is a critical feature of many important eukaryotic signal transduction cascades. Only recently, however, have studies in Arabidopsis thaliana described that some of the most fundamental plant signal transduction pathways, including the photoperiodic flowering pathway, are functionally affected by 14-3-3s. There are pivotal points in the photoperiod pathway that are characterized by the accumulation, localization and stability of critical protein factors, all of which are strongly affected by light quality and photoperiod duration. These mechanisms (localization, phosphorylation, regulated proteolysis) are the same as those regulated by 14-3-3 proteins in other systems. Yet it is only recently that well characterized 14-3-3 genetic tools have become available in sufficient diversity to make it possible to truly tie 14-3-3 interactions to light signaling and flowering. This review presents an overview of photoperiodic flowering signaling and direct 14-3-3 participation in the process, coupled with a discussion of the overlapping and specific roles of 14-3-3s which present confounding issues in the functional dissection of this family of signaling proteins.Key words: isoform specificity, protein interaction, phosphorylation, signaling     

磷脂酶Dβ在拟南芥低温信号中的转导作用

磷脂酶D(PLD)不仅是植物中一类主要的磷脂水解酶,而且是一类重要的跨膜信号转导酶类.PLD的磷脂降解功能和信号转导功能均影响植物的抗冻性.本研究以PLDβ基因被敲除的拟南芥突变体及其野生型植株为材料,进行低温驯化和冻害胁迫处理,并分析其作用途径.结果表明,PLDβ基因介导低温信号转导作用,参与渗透调节途径中脯氨酸的调控和抗氧化系统中过氧化氢酶(CAT)活性的调控,并且与低温信号激素ABA不在同一条信号转导途径.本研究为探索通过调控PLD的活性提高植物抗冻性提供了新的途径,并为深入揭示植物的抗冻机理以及磷脂信号转导机制提供实验支持.     

赤霉素信号转导与植物的矮化

论述近年来在拟南芥、水稻等模式植物中赤霉素信号转导的研究进展。通过对赤霉素相关突变体的生理研究 ,鉴定出几个介入赤霉素信号转导过程的重要基因 ,并对这些基因的产物进行分析 ,根据相应的蛋白特征结构域 ,推导了它们可能具有的功能。利用双突变体 ,分析了这些基因的上下游关系 ,确定了在植物中 ,GA信号转导的几个途径。在此基础上提出了赤霉素信号转导的基本模式 :阻遏是GA信号转导过程中最基本的方式 ,GA信号通过去除阻遏作用来激活转导途径 ,从而调节GA相关的生长与发育。     

逐渐干旱胁迫下生物土壤结皮中土生对齿藓和真藓信号转导物质的响应

以生物土壤结皮中土生对齿藓(Didymodon vinealis)和真藓(Bryum argenteum)为材料,研究了逐渐干旱胁迫下二者的信号传导相关物质的响应。结果表明:随干旱胁迫的增强,2种苔藓的细胞膜与液泡膜H+-ATPase活性增强,提高了二者的K+含量,增加了二者的渗透压,促进了二者的抗旱信号转导物质的合成;ABA对二者的信号转导作用都不明显,NO对土生对齿藓的抗旱作用不明显,但能提高真藓的抗旱性,而Ca2+只对土生对齿藓有明显信号转导作用,对真藓作用不明显。