丝氨酸/苏氨酸蛋白磷酸酶与DNA损伤应答

DNA损伤应答(DNA damage response,DDR)是维持基因组稳定性的核心机制,对DDR的研究不仅有助于阐明癌症发生发展的机理,同时也为癌症治疗和抗癌新药开发提供生物学基础。蛋白质翻译后修饰,尤其是蛋白激酶介导的磷酸化修饰和蛋白磷酸酶介导的去磷酸化修饰,参与调控绝大多数的生命活动过程,包括DDR。对蛋白激酶ATM/ATR/CHK2/CHK1介导的DDR的研究已经比较透彻,但是对蛋白磷酸酶在DDR中的功能研究还有待加强和深入。比较全面地综述丝氨酸/苏氨酸蛋白磷酸酶在DDR中的功能并探讨在抗癌新药开发中的前景。     

微囊藻毒素的毒性效应与蛋白磷酸酶2A

蛋白磷酸酶2A(protein phosphatase 2A,PP2A)是蛋白磷酸酶家族的主要成员,在蛋白质可逆磷酸化过程中与蛋白激酶一样起着举足轻重的作用。自然界存在很多天然毒素可特异性地作用于PP2A从而影响体内蛋白质的可逆磷酸化,其中微囊藻毒素由于急性肝毒性和强促癌活性日益引起关注。尽管确切的机制仍未探明,但从目前的研究来看,微囊藻毒素产生毒性的机制可能与其引起细胞氧化应激、DNA损伤、细胞骨架的破坏以及诱导细胞凋亡相关。而PP2A在氧化应激、DNA损伤修复及维持细胞骨架稳态中起着重要作用,并能调控凋亡相关激酶CaMKII和Bcl-2家族蛋白,这对更好地理解微囊藻毒素LR如何通过影响PP2A而产生毒作用提供了新思路。     

蓝藻的蛋白质翻译后修饰研究进展

蛋白质翻译后修饰系统几乎参与了细胞所有的正常生命活动过程,并发挥着重要的调控作用。目前,基于生物质谱技术进行蛋白质翻译后修饰的规模化分析鉴定,已经成为蛋白质组学研究的核心内容之一。近年来的研究表明,蓝藻细胞中存在着复杂的蛋白质翻译后修饰系统,如磷酸化,乙酰化,甲基化,糖基化,氧化等,这些翻译后修饰在蓝藻细胞的代谢过程中可能发挥着重要的调控作用。本文主要针对蓝藻细胞中蛋白质翻译后修饰的发现与鉴定,以及翻译后修饰潜在的生物学功能展开简要综述。     

蛋白激酶与神经系统功能调控

翻译后的磷酸化修饰是蛋白质结构和功能的重要调节方式。催化蛋白质磷酸化过程的蛋白激酶广泛参与神经发育、感觉、学习记忆、情绪与认知等生理过程及神经退行性疾病、慢性疼痛及精神疾病等病理生理过程,是生命科学领域的研究热点。现将举例说明蛋白激酶在神经系统内的重要作用,并介绍以蛋白激酶为靶点的药物开发现况。     

蛋白质磷酸化修饰的研究进展

蛋白质磷酸化是最常见、最重要的一种蛋白质翻译后修饰方式,它参与和调控生物体内的许多生命活动。通过蛋白质的磷酸化与去磷酸化,调控信号转导、基因表达、细胞周期等诸多细胞过程。随着蛋白质组学技术的发展和应用,蛋白质磷酸化的研究越来越受到广泛的重视。我们介绍了蛋白质磷酸化修饰的主要类型与功能、磷酸化蛋白质分析样品的富集及制备、磷酸化蛋白的鉴定及磷酸化位点的预测、蛋白分离后磷酸化蛋白的检测,及蛋白质磷酸化的分子机制,并综述了近年来国内外的主要相关研究进展。     

mTOR信号通路的生物学功能

哺乳动物的雷帕霉素靶(mammalian target of rapamycin,mTOR)是一种非典型丝氨酸/苏氨酸蛋白激酶,可整合细胞外信号,磷酸化下游靶蛋白核糖体p70S6激酶,如S6K1及4E-BP1,影响基因转录与蛋白质翻译,从而参与调控细胞生长、增殖等过程。mTOR的生物学功能的多样性,使其成为当今生物学研究的焦点之一。mTOR与蛋白质合成、免疫、细胞运动及代谢、细胞凋亡及自噬等均有联系。     

植物蛋白磷酸化的检测方法

蛋白磷酸化是一种重要的蛋白质翻译后修饰方式,几乎参与植物所有生命过程的调节。蛋白磷酸化过程主要指在蛋白激酶的催化作用下,将三磷酸腺苷(ATP)上的γ位磷酸基团转移到底物蛋白特定氨基酸残基上的过程。底物蛋白上被磷酸化的常见氨基酸有丝氨酸、苏氨酸及酪氨酸,磷酸基团与氨基酸中的羟基通过酯键连接。该文详细描述了几种常用的蛋白质体外及体内磷酸化的检测方法及注意事项。     

植物蔗糖非发酵-1相关蛋白激酶家族研究进展

蛋白质磷酸化与去磷酸化过程在细胞的信号转导网络中起关键的作用,是生物体中普遍存在的一种调节机制。植物中的蛋白激酶通过磷酸化和去磷酸化在调节ABA信号传导、能量缺失反应和非生物胁迫反应过程中有着重要的作用。其中,植物蔗糖非发酵-1相关蛋白激酶(sucrose non-fermenting-1-related protein kinase,SnRK)是植物蛋白激酶家族中一个重要家族,它们与酵母中的SNF1(sucrose non-fermenting-1,SNF1)和哺乳动物中的AMPK(AMP-activated protein kinase,AMPK)同源,具有与它们相似和自身独特的功能,根据其氨基酸序列的同源性和表达模式的差异可分为3个亚组:SnRK1、SnRK2和SnRK3。目前,在拟南芥、水稻、豆科植物、高粱以及苔藓植物等基因组中都发现了大量的SnRK蛋白激酶,它们广泛参与了植物的生长发育、病虫害防御、ABA和非生物胁迫等各种信号的应答反应。     

植物蛋白质翻译水平的调控

不同的逆境条件可引起生物机体不同的应答反应,其中PKR(protein kinase double-stranded RNA-dependent)、PERK(PKR-like endoplasmic reticulum kinase)、HRI(heme-regulated inhibitor)和GCN2(general control non-derepressible-2)激活后使真核蛋白翻译起始因子2(e IF2)磷酸化,抑制蛋白质的翻译起始,帮助生物体适应各种逆境条件。雷帕霉素的靶蛋白(TOR)是一个进化上相对保守的丝氨酸/苏氨酸激酶,参与细胞生长与增殖、新陈代谢以及蛋白质的翻译等进程,对细胞的正常生长发育有重要作用。近几年的研究表明,e IF2和TOR介导的信号途径在植物中是保守的,共同参与了蛋白翻译水平的调控。本文综述了植物中e IF2和TOR介导的信号途径对蛋白翻译过程的调控机制,以及蛋白质翻译在植物响应逆境中的重要作用。     

组蛋白磷酸化修饰与精子发生

组蛋白磷酸化是组蛋白氨基酸残基的磷酸化修饰,是一类重要的翻译后修饰,与有丝分裂和减数分裂的染色质压缩、染色质功能调节、转录的激活与抑制、DNA损伤修复以及物质代谢等多种机制相关。文章对国内外近10年多种代表性生物精子发生(孢子形成)的相关文献进行总结,论述了组蛋白磷酸化在精子发生中调控蛋白质作用因子的结合位点、调控减数分裂过程中的DNA复制与重组、保障正确的染色质重塑、对减数分裂后的成熟精子核的完全包装等重要功能。这些发现加深了人们对于组蛋白及其翻译后修饰在精子发生及分化中作用的理解。     

超嗜热古菌整合性遗传元件的研究进展

细菌中整合性遗传元件与DNA修饰和防御、毒力因子传播以及次级代谢等生理功能存在关联,而相关研究在超嗜热古菌中尚处于起步阶段。本文综述了超嗜热古菌中整合性病毒、质粒及基因组岛等整合性遗传元件的分类、整合及维持机制。展示了整合性遗传元件参与的水平基因转移过程在超嗜热古菌基因组演化中扮演的重要角色。整合性遗传元件相关功能基因组学研究为理解超嗜热古菌的多样性及其环境适应性机制提供了新的视角。     

古菌中蛋白甲基化修饰的研究进展

蛋白甲基化修饰是翻译后修饰的主要方式之一,越来越多的报道证实古菌中存在这类蛋白修饰。目前古菌中一些甲基转移酶已经鉴定出来,但对其作用机制还不太清楚。本文对目前古菌中已经发现的蛋白质甲基转移酶和甲基化修饰可能的作用进行了总结。古菌中蛋白的甲基化修饰能够提高蛋白稳定性、影响侧链构象变化及与其他分子的相互作用,涉及DNA损伤修复和应激反应等途径。最后,本文对今后古菌中蛋白甲基化修饰的研究方向进行了展望。     

Lipid Metabolism in Photoreceptor Membranes: Regulation and Mechanisms

Lipid metabolism in photoreceptor rod outer segments has attracted considerable attention because of its importance in providing the appropriate environment for supporting an efficient phototransduction mechanism. Recent studies suggest that lipid metabolism in these membranes is involved in the generation of second messengers and in signal transduction mechanisms. Phospholipid turnover is tightly regulated by phosphorylation-dephosphorylation reactions and light, and provides, in turn, with molecules capable of activating protein kinases and cellular processes such as membrane fusion or light-adaptation. These findings suggest that photoreceptor membrane lipids are more than just important structural components of the visual cell rod outer segment.     

极端嗜热古菌DNA修复核酸内切酶的研究进展

极端嗜热古菌由于生活在高温环境,其基因组DNA面临着严重的挑战,因此,它们如何维持其基因组稳定是本研究领域最为关注的科学问题之一。极端嗜热古菌具有与常温微生物相似的自发突变频率,暗示着它们比常温微生物具有更加有效的DNA修复体系进行修复高温所造成的基因组DNA损伤。目前,极端嗜热古菌DNA修复的分子机制尚不清楚。核酸内切酶在DNA修复途径中发挥着重要的作用。基因组序列显示极端嗜热古菌编码多种DNA修复核酸内切酶,但是其研究尚处于初期阶段。本文综述了极端嗜热古菌DNA修复核酸内切酶Nuc S、Endo V、Endo Q、XPF和Hjc的研究进展,并对今后的研究提出了展望。     

Physiological roles of mitogen-activated-protein-kinase-activated p38-regulated/activated protein kinase

Mitogen-activated protein kinases (MAPKs) are a family of proteins that constitute signaling pathways involved in processes that control gene expression, cell division, cell survival, apoptosis, metabolism, differentiation and motility. The MAPK pathways can be divided into conventional and atypical MAPK pathways. The first group converts a signal into a cellular response through a relay of three consecutive phosphorylation events exerted by MAPK kinase kinases, MAPK kinase, and MAPK. Atypical MAPK pathways are not organized into this three-tiered cascade. MAPK that belongs to both conventional and atypical MAPK pathways can phosphorylate both non-protein kinase substrates and other protein kinases. The latter are referred to as MAPK-activated protein kinases. This review focuses on one such MAPK-activated protein kinase, MAPK-activated protein kinase 5 (MK5) or p38-regulated/activated protein kinase (PRAK). This protein is highly conserved throughout the animal kingdom and seems to be the target of both conventional and atypical MAPK pathways. Recent findings on the regulation of the activity and subcellular localization, bona fide interaction partners and physiological roles of MK5/PRAK are discussed.     

In vivo functions of mitogen-activated protein kinases: conclusions from knock-in and knock-out mice

Multicellular organisms achieve intercellular communication by means of signalling molecules whose effect on the target cell is mediated by signal transduction pathways. Such pathways relay, amplify and integrate signals to elicit appropriate biological responses. Protein kinases form crucial intermediate components of numerous signalling pathways. One group of protein kinases, the mitogen-activated protein kinases (MAP kinases) are kinases involved in signalling pathways that respond primarily to mitogens and stress stimuli. In vitro studies revealed that the MAP kinases are implicated in several cellular processes, including cell division, differentiation, cell survival/apoptosis, gene expression, motility and metabolism. As such, dysfunction of specific MAP kinases is associated with diseases such as cancer and immunological disorders. However, the genuine in vivo functions of many MAP kinases remain elusive. Genetically modified mouse models deficient in a specific MAP kinase or expressing a constitutive active or a dominant negative variant of a particular MAP kinase offer valuable tools for elucidating the biological role of these protein kinases. In this review, we focus on the current status of MAP kinase knock-in and knock-out mouse models and their phenotypes. Moreover, examples of the application of MAP kinase transgenic mice for validating therapeutic properties of specific MAP kinase inhibitors, and for investigating the role of MAP kinase in pathogen-host interactions will be discussed.     

The regulation of mitochondrial physiology by organelle-associated GTP-binding proteins

Recent studies have shown that GTP-binding proteins can modulate mitochondrial membrane fusion and fission. Furthermore, GTP-binding proteins can regulate the binding of ribosomes to the mitochondrial membrane and may facilitate the import of proteins through contact points between inner and outer mitochondrial membranes. Mitochondrial GTP-binding proteins therefore appear to have the potential to modulate physiological function of the organelle and may also be involved in cellular processes such as cellular transformation. A beginning has been made on the characterization of mitochondrial GTP-binding proteins and the DNA sequence of one protein has become newly available. Future studies are needed to determine whether GTP-binding proteins are interacting with cell signalling molecules such as protein kinases in the mitochondria.     

The RIO kinases: an atypical protein kinase family required for ribosome biogenesis and cell cycle progression

Atypical protein kinases (aPKs) include proteins known to be involved in the phosphorylation-mediated regulation of a wide variety of cellular processes, as well as some for which the function is, as yet, unknown. At present, 13 families of aPKs have been identified in the human genome. This review briefly summarizes their known properties, but concentrates in particular on the RIO family of aPKs. Representatives of this family are present in organisms varying from archaea to humans. All these organisms contain at least two RIO proteins, Rio1 and Rio2, but a third Rio3 group is present in multicellular eukaryotes. Crystal structures of A. fulgidus Rio1 and Rio2 have shown that whereas the overall fold of these enzymes resembles typical protein kinases, some of the kinase structural domains, particularly those involved in peptide substrate binding, are not present. The mode of binding of nucleotides also differs from other kinases. While the enzymatic activity of Rio1 and Rio2 has been demonstrated and both have been shown to be essential in S. cerevisiae and required for proper cell cycle progression and chromosome maintenance, the biological substrates of RIO proteins still remain to be identified.