G蛋白信号调节蛋白作为中枢神经系统药物新靶点研究进展

G蛋白偶联受体(G-prote in-coup led receptors,GPCR)是许多治疗药物的作用靶点。G蛋白信号调节蛋白(regu latorof G-prote in signaling,RGS)属一类新发现的蛋白家族,它们在GPCR信号传导中起重要作用。一般来说RGS可加速G蛋白失活进而终止GPCR信号传导,但也有些RGS同时具有效应分子和信号传递功能。兼具GPCR激动和RGS抑制功能的药物将大大增强信号传导,同时还能增加激动剂的区域特异性。由于RGS的多样性,组织分布特异性以及较强的调节活性,RGS很可能成为寻找新型中枢神经系统疾病治疗药物的新靶点。     

针对G蛋白偶联受体的药物筛选新方法

G蛋白偶联受体（GPCR）为具有7个跨膜螺旋的蛋白质受体，是人体内最大的蛋白质家族，其为极重要的药物靶点。本文针对GPCR的固有激活和变构效应的药物筛选模型开发新进展和高内涵药物筛选新技术进行综述。     

G蛋白偶联受体在肝细胞癌中调控作用研究进展

G蛋白偶联受体(GPCR),又称为7-α螺旋跨膜蛋白受体,是己知的3类涉及跨膜信号转导的膜受体之一。GPCR与G蛋白结合产生生物学效应,对机体生理功能和病理过程有广泛的调控作用。大量研究表明,GPCR通过调节下游某些信号的转导途径影响肝癌细胞的增殖、侵袭和转移过程,参与肝细胞癌(HCC)的发生和发展。本文就趋化因子受体、前列腺素受体、肾上腺素受体和血管紧张素受体等GPCR及其相关的信号通路在HCC发生发展进程中的作用进行综述,并对靶向GPCR的HCC治疗前景予以展望。     

G蛋白偶联受体组成性活性及反向激动剂研究进展

G蛋白偶联受体（GPCR）是受体中家族成员最多的一大类，其活性涉及体内绝大部分的生理功能，在药物研发过程中是主要的药物作用靶标。研究表明，GPCR及其突变体在缺乏配体结合的情况下，能自发地产生一定程度的内在活性，即GPCR的组成性活性（constitutive activity）；其相应的反向激动剂与GPCR结合能降低受体的组成性活性，在药物治疗学上具有重要意义。愈来愈多的实验表明，GPCR组成性活性及反向激动剂的研究具有广阔和实际的应用前景，对其进行深入研究在受体学说领域和药物研发过程中具有重要理论意义。     

Gαq蛋白和T淋巴细胞稳态增殖在自身免疫中的作用研究

异源三聚体G蛋白在跨膜信号转导中扮演重要角色,介导信号从细胞表面传递到细胞内部。哺乳动物细胞中1 000多种G蛋白偶联受体（GPCR）的信号传导并将其转化为细胞应答都是G蛋白共同功能。根据α亚基单位的不同,G蛋白可分为4个亚家族：Gs、Gi/o、Gq/11和G12/13。大多数的α亚基高表达于免疫细胞表面。     

G蛋白偶联受体4与血管内皮生长因子相关性的研究进展

<正>G蛋白偶联受体(GPCR)是具有7个跨膜螺旋的一类受体蛋白质,对生物起着重要的作用。质子感知受体卵巢癌G蛋白偶联受体1(OGR1)是GPCRs中的1个亚家族,G蛋白偶联受体4(GPR4)为OGR1亚家族4种受体中的一种,广泛分布于人体各种肿瘤组织细胞中,参与并影响肿瘤的发生、发展。研究发现恶性肿瘤由于增生过快,局部组织严重缺氧,形成酸性环境,可通过直接或     

Lucy-tag促进海七鳃鳗嗅觉受体细胞膜表达

目的阐明一种多肽标签Lucy-tag对于海七鳃鳗(Petromyzon marinus)嗅觉受体膜表达的促进作用。方法用免疫细胞化学、双荧光素酶报告基因(Luciferase)系统和钙流检测法,验证多肽标签Lucy-tag对于海七鳃鳗嗅觉受体的作用。结果多肽标签Lucy-tag促进了20个嗅觉受体中13个嗅觉受体的膜表达,并且Lucy-tag不影响嗅觉受体的固有活性,Lucy-tag也不影响G蛋白偶联受体(G protein coupled receptor,GPCR)的IP_3信号通路。结论该技术为寻找嗅觉受体的配体提供了有利的技术手段,为进一步深入研究GPCR与配体的功能奠定了良好的理论基础。     

G蛋白偶联受体激酶活性调控及其在恶性肿瘤中的作用

G蛋白偶联受体(GPCR),是一类重要的细胞表面受体。G蛋白偶联受体激酶(GRK)属于丝氨酸/苏氨酸蛋白激酶家族,其亚型广泛存在与各种组织,能够特异性地使活化的GPCR发生磷酸化及脱敏,从而终止GPCR介导的信号转导通路。新的研究还发现,GRK不仅作用于GPCR,也可以通过使非GPCR磷酸化或通过非磷酸化作用参与信号转导。GRK不仅能够调节GPCR和非GPCR,其自身活性也可受到多种因素的调节。本文结合GRK的多种功能作用和GRK活性调控,对GRK在脑、内分泌、生殖系统、消化系统及黑色素肿瘤中的作用做简要综述。     

β1-肾上腺素受体与中枢神经系统疾病相关性研究进展

G-蛋白偶联受体（GPCRs）是一类功能最全面且最为庞大的跨膜受体家族。β-肾上腺素受体（β—adrenoceptor,β—AR）是经典的G蛋白偶联受体家族的成员,其生物学效应由经典的Gs—cAMP—PKA信号通路介导。人们对β-肾上腺素的研究主要集中于其对心力衰竭、心血管、心肌自律性和传导功能等的作用。     

肾脏中G蛋白偶联受体信号转导的多样性

G蛋白偶联受体(GPCR)是最重要的药物靶点之一;临床有超过30%处方药是直接作用在GPCR上的。在肾脏中,升压素受体、血管紧张素受体、内皮素受体、前列腺素受体和嘌呤受体等都对肾脏的多种功能有重要的调控作用,也是重要的治疗肾病的药物靶点。多种靶向这些肾脏GPCR的激动剂或者拮抗剂已经进入临床应用或者临床测试阶段。然而,这些GPCR药物的设计主要以激动剂和拮抗剂进行区分,与GPCR的功能多样性存在着一定的鸿沟。我们最近在研究靶向血管紧张素受体(AT1R)的药理学研究过程中,不仅发现了高同型半胱氨酸是血管紧张素受体的内源性配体,还发现Arrestin偏向性信号途径不仅可以介导传统的第二波信号途径,还可以在时序上进行第一波信号转导,通过激活TRPC3来促进肾上腺素的释放,从而产生在治疗心血管疾病时的有害作用。我们据此提出了更合理的靶向AT1R开发药物的方法。不仅如此,我们还针对升压素受体的磷酸化编码,阐明了Arrestin对GPCR的磷酸化编码的识别机制,Arrestin的多聚脯氨酸码头的分选机制,以及配体通过操控受体7此跨膜核心与Arrestin的相互作用来指导Arrestin功能的机制。这些研究工作为以后特异性的靶向GPCR的Arrestin信号通路开发药物奠定了基础。     

Constitutive activity of G-protein-coupled receptors: cause of disease and common property of wild-type receptors

The aim of this review is to provide a systematic overview on constitutively active G-protein-coupled receptors (GPCRs), a rapidly evolving area in signal transduction research. We will discuss mechanisms, pharmacological tools and methodological approaches to analyze constitutive activity. The two-state model defines constitutive activity as the ability of a GPCR to undergo agonist-independent isomerization from an inactive (R) state to an active (R*) state. While the two-state model explains basic concepts of constitutive GPCR activity and inverse agonism, there is increasing evidence for multiple active GPCR conformations with distinct biological activities. As a result of constitutive GPCR activity, basal G-protein activity increases. Until now, constitutive activity has been observed for more than 60 wild-type GPCRs from the families 1-3 and from different species including humans and commonly used laboratory animal species. Additionally, several naturally occurring and disease-causing GPCR mutants with increased constitutive activity relative to wild-type GPCRs have been identified. Alternative splicing, RNA editing, polymorphisms within a given species, species variants and coupling to specific G-proteins all modulate the constitutive activity of GPCRs, providing multiple regulatory switches to fine-tune basal cellular activities. The most important pharmacological tools to analyze constitutive activity are inverse agonists and Na(+) that stabilize the R state, and pertussis toxin that uncouples GPCRs from G(i)/G(o)-proteins. Constitutive activity is observed at low and high GPCR expression levels, in native systems and in recombinant systems, and has been reported for GPCRs coupled to G(s)-, G(i)- and G(q)-proteins. Constitutive activity of neurotransmitter GPCRs may provide a tonic support for basal neuronal activity. For the majority of GPCRs known to be constitutively active, inverse agonists have already been identified. Inverse agonists may be useful in the treatment of neuropsychiatric and cardiovascular diseases and of diseases caused by constitutively active GPCR mutants.     

Regulators of G-protein signalling as new central nervous system drug targets

G-protein-coupled receptors (GPCRs) are major targets for drug discovery. The regulator of G-protein signalling (RGS)-protein family has important roles in GPCR signal transduction. RGS proteins contain a conserved RGS-box, which is often accompanied by other signalling regulatory elements. RGS proteins accelerate the deactivation of G proteins to reduce GPCR signalling; however, some also have an effector function and transmit signals. Combining GPCR agonists with RGS inhibitors should potentiate responses, and could markedly increase the agonist's regional specificity. The diversity of RGS proteins with highly localized and dynamically regulated distributions in brain makes them attractive targets for pharmacotherapy of central nervous system disorders.     

Signal transduction pathways of G protein-coupled receptors and their cross-talk with receptor tyrosine kinases: lessons from bradykinin signaling

G protein-coupled receptors (GPCRs) represent a major class of drug targets. Recent investigation of GPCR signaling has revealed interesting novel features of their signal transduction pathways which may be of great relevance to drug application and the development of novel drugs. Firstly, a single class of GPCRs such as the bradykinin type 2 receptor (B2R) may couple to different classes of G proteins in a cell-specific and time-dependent manner, resulting in simultaneous or consecutive initiation of different signaling chains. Secondly, the different signaling pathways emanating from one or several GPCRs exhibit extensive cross-talk, resulting in positive or negative signal modulation. Thirdly, GPCRs including B2R have the capacity for generation of mitogenic signals. GPCR-induced mitogenic signaling involves activation of the p44/p42 "mitogen activated protein kinases" (MAPK) and frequently "transactivation" of receptor tyrosine kinases (RTKs), an unrelated class of receptors for mitogenic polypeptides, via currently only partly understood pathways. Cytoplasmic tyrosine kinases and protein-tyrosine phosphatases (PTPs) which regulate RTK signaling are likely mediators of RTK transactivation in response to GPCRs. Finally, GPCR signaling is the subject of regulation by RTKs and other tyrosine kinases, including tyrosine phosphorylation of GPCRs itself, of G proteins, and of downstream molecules such as members of the protein kinase C family. In conclusion, known agonists of GPCRs are likely to have unexpected effects on RTK pathways and activators of signal-mediating enzymes previously thought to be exclusively linked to RTK activity such as tyrosine kinases or PTPs may be of much interest for modulating GPCR-mediated biological responses.     

G protein-coupled receptors and their signaling pathways: classical therapeutical targets susceptible to novel therapeutic concepts

In recent years, new strategies in cancer therapy have been developed targeting key signaling molecules in the receptor tyrosine kinase signal transduction pathway. In contrast, most therapeutical concepts to manipulate G protein-coupled receptors (GPCR)-mediated disorders are still limited to the use of receptor-specific agonists or antagonists. Visible progress in the understanding of GPCR signaling complexity, especially the detection of several families of highly target- and cell-specific regulator proteins of GPCRs, G proteins, and effector components may open new horizons to develop novel therapeutical concepts targeting GPCR signaling elements. Thus, this review will focus on different molecular levels that may be of particular interest in terms of new drug development such as: (i) GPCR subtypes, allosteric binding sites, dimerization and constitutive activity, the use of RAMPs (receptor-activity-modifying proteins) and RASSLs (receptor activated solely by synthetic ligands); (ii) AGS (activators of G protein signaling) and RGS (regulators of G protein signaling) proteins which modify G protein activity; (iii) the high diversity of isozymes involved in the generation, signal transmission, and degradation of second messenger molecules.     

Structural mechanism of GPCR-arrestin interaction: recent breakthroughs

G protein-coupled receptors (GPCRs) are a major membrane receptor family with important physiological and pathological functions. In the classical signaling pathway, ligand-activated GPCRs couple to G proteins, thereby inducing G protein-dependent signaling pathways and phosphorylation by G protein-coupled receptor kinases (GRKs). This leads to an interaction with arrestins, which results in GPCR desensitization. Recently, non-classical GPCR signaling pathways, mediated by GPCR-bound arrestins, have been identified. Consequently, arrestins play important roles in GPCR signaling not only with respect to desensitization but also in relation to G protein-independent signal transduction. These findings have led to efforts to develop functionally biased (i.e. signal transduction biased) GPCR-targeting drugs. One of these efforts is aimed at understanding the structural mechanism of functionally biased GPCR signaling, which includes understanding the G protein-selectivity or arrestin-selectivity of GPCRs. This goal has not yet been achieved; however, great progress has been made during the last 3 years toward understanding the structural mechanism of GPCR-mediated arrestin activation. This review will discuss the recent breakthroughs in the conformational understanding of GPCR-arrestin interaction.     

Functional signaling biases in G protein-coupled receptors: Game Theory and receptor dynamics

Pharmacotherapeutic targeting of G protein-coupled receptors (GPCRs) is perhaps the most important field of drug design, as agents designed to control these receptors constitute more than half of the pharmacopeia. Initially GPCRs were considered to be unitary entities, possessing all of their potential functionality in their characteristic heptahelical core. Early models of the functional activity of GPCRs considered them to possess just a simple 'on' or 'off' status. Recent research however has allowed us to realize that GPCR functionality is dependent upon many other proteins outside of the heptahelical core, on the site of GPCR expression in a tissue or a microdomain in a cell, and, most importantly, on the formation of differential 'active' states preferentially coupled to specific signal transduction structures. The recognition of such signaling diversity has facilitated the ability to appreciate and identify ligands for GPCRs that demonstrate a bias towards one signaling form of a receptor to another. However while potentially increasing our ability for selective signal targeting, our approach to understanding the physiological ramifications of systemic signaling manipulation is underdeveloped. This explosion in the complexity of GPCR signaling is now becoming familiar territory to receptor biologists, yet the application of this knowledge to drug design is relatively limited. This review will attempt to outline potential pitfalls and unseen benefits of using signaling bias in therapeutic design as well as highlighting new applications such as Game Theory for uncovering new therapeutic applications for biased agonists.     

Constitutively activated G protein-coupled receptors: a novel approach to CNS drug discovery

G protein-coupled receptors (GPCRs) represent a major class of signal transduction proteins that modulate various biological functions. GPCRs are one of the most common targets for drug development-currently, 39 of the top 100 marketed drugs in use act directly or indirectly through activation or blockade of GPCR-mediated receptors. Nearly 160 GPCRs have been identified based on their gene sequence and their ability to interact with known endogenous ligands. However, an estimated 500-800 additional GPCRs have been classified as "orphan" receptors (oGPCRs) because their endogenous ligands have not yet been identified. Given that known GPCRs have proven to be such clinically useful drug targets, these oGPCRs represent a rich group of receptor targets for the development of novel and improved medicines. To develop ligands for these potential drug targets requires the ability to identify groups or pools of GPCRs that are likely to be involved in a specific disease process (obesity, schizophrenia, depression, etc.) and to dissect out the pharmacological and signal transduction differences between these GPCR subtypes. It also requires the development of assays to detect ligands of GPCRs even when the endogenous ligands are unidentified. This paper will review novel strategies to identify clinically interesting oGPCRs and to screen for small molecules that act as ligands without prior knowledge of endogenous ligands. This involves the use of constitutively activated GPCRs, a technology that provides a unique opportunity to identify several classes of pharmacological agents, including agonists, inverse agonists and allosteric modulators.     

Computational methods in drug design: Modeling G protein-coupled receptor monomers, dimers, and oligomers

G protein-coupled receptors (GPCRs) are membrane proteins that serve as very important links through which cellular signal transduction mechanisms are activated. Many vital physiological events such as sensory perception, immune defense, cell communication, chemotaxis, and neurotransmission are mediated by GPCRs. Not surprisingly, GPCRs are major targets for drug development today. Most modeling studies in the GPCR field have focused upon the creation of a model of a single GPCR (ie, a GPCR monomer) based upon the crystal structure of the Class A GPCR, rhodopsin. However, the emerging concept of GPCR dimerization has challenged our notions of the monomeric GPCR as functional unit. Recent work has shown not only that many GPCRs exist as homo- and heterodimers but also that GPCR oligomeric assembly may have important functional roles. This review focuses first on methodology for the creation of monomeric GPCR models. Special emphasis is given to the identification of localized regions where the structure of a GPCR may diverge from that of bovine rhodopsin. The review then focuses on GPCR dimers and oligomers and the bioinformatics methods available for identifying homo- and heterodimer interfaces.     

The evolving role of lipid rafts and caveolae in G protein-coupled receptor signaling: implications for molecular pharmacology

The many components of G-protein-coupled receptor (GPCR) signal transduction provide cells with numerous combinations with which to customize their responses to hormones, neurotransmitters, and pharmacologic agonists. GPCRs function as guanine nucleotide exchange factors for heterotrimeric (alpha, beta, gamma) G proteins, thereby promoting exchange of GTP for GDP and, in turn, the activation of 'downstream' signaling components. Recent data indicate that individual cells express mRNA for perhaps over 100 different GPCRs (out of a total of nearly a thousand GPCR genes), several different combinations of G-protein subunits, multiple regulators of G-protein signaling proteins (which function as GTPase activating proteins), and various isoforms of downstream effector molecules. The differential expression of such protein combinations allows for modulation of signals that are customized for a specific cell type, perhaps at different states of maturation or differentiation. In addition, in the linear arrangement of molecular interactions involved in a given GPCR-G-protein-effector pathway, one needs to consider the localization of receptors and post-receptor components in subcellular compartments, microdomains, and molecular complexes, and to understand the movement of proteins between these compartments. Co-localization of signaling components, many of which are expressed at low overall concentrations, allows cells to tailor their responses by arranging, or spatially organizing in unique and kinetically favorable ways, the molecules involved in GPCR signal transduction. This review focuses on the role of lipid rafts and a subpopulation of such rafts, caveolae, as a key spatial compartment enriched in components of GPCR signal transduction. Recent data suggest cell-specific patterns for expression of those components in lipid rafts and caveolae. Such domains likely define functionally important, cell-specific regions of signaling by GPCRs and drugs active at those GPCRs.