反义技术及其在G蛋白研究中的应用

反义技术至少包括反义寡核苷酸技术、反义RNA技术和核酶技术.在G蛋白研究中,反义技术在G蛋白受体及受体亚型研究、G蛋白转导信号特异性研究方面及对G蛋白耦联信号传导途径与其他信号传导途径之间“cross talk”认识方面的研究中,有着广泛的应用.     

溶血磷脂酸--一种具有多种生物学功能的磷脂信号分子

溶血磷脂酸(Lysophosphatidic acid,LPA)是迄今发现的一种最小、结构最简单的磷脂,它是真核细胞磷脂生物合成早期阶段的关键性前体,甘油磷脂代谢的中间产物。60年代初,Vogt等人在实验中观察到,LPA能够引起免离体肠平滑肌收缩。这一现象使人们认识到LPA不仅仅是生物膜的组成成分可能还具有某些生物学功能。随后越来越多的研究表明:LPA作为一种细胞间的磷脂信使,可以激活G蛋白偶联受体,引起生长激素样作用,从而产生广泛的生物学效应。LPA对细胞的生长、增殖、分化及细胞内信息传递产生多种影响,在维持机体正常的生理功能,参与各种病理过程的发     

黑皮质素受体-4调节通路的研究进展

黑皮质素系统来自阿片-促黑素细胞皮质素原,在中枢摄食行为和能量平衡代谢中起到重要作用,此系统生理功能的发挥主要通过与下丘脑神经元细胞上特定膜受体（黑皮质素受体）结合完成。黑皮质素受体（MCR）有五种亚型（MC1R-MC5R）,其中参与体重调节的受体主要是黑皮质素受体3（MC3R）和黑皮质素受体4（MC4R）。MC4R属于G蛋白耦联受体,具有七次跨膜结构。作为一种膜受体,MC4R发挥体重调节作用,一方面受外界激动剂或拮抗剂的调节;另一方面,此受体活化后会影响到细胞内的信号调节通路。研究MC4R的功能首先要了解受体的结构,本文对G蛋白耦联受体的结构进行了较详细的叙述,MC4R经信号调节通路,激活腺苷酸环化酶,增加cAMP的浓度,最终通过影响细胞内基因的转录和翻译,来调节体重和能量的消耗。     

细胞外钙受体相互作用蛋白的研究进展

细胞外钙受体(CaR)为G蛋白偶联受体超家族中的成员,它的大部分作用是以Gαi,Gαq和Gα12/13为中介的,但由G蛋白α亚基介导的作用并不能完全解释CaR的生物学效应.与CaR相互作用蛋白如抑制蛋白、G蛋白受体激酶、受体激活修饰蛋白、丝蛋白、钾通道、小窝蛋白等结构和信号蛋白赋予CaR独特的信号转导特征,并能够更充分说明CaR在不同组织和细胞中所发挥的作用.本文将对上述几种与其相互作用蛋白及它们所产生的生物学效应做一综述.     

心脏疾病中G蛋白的变化

G蛋白是一类重要的信号转导分子,其生理功能是将细胞膜受体所识别的各种细胞外信号同细胞内一系列效应分子偶联起来,引起核基因转录及蛋白质结构和功能的变化。G蛋白在心脏表达的亚型有Gs、Gi/o、Gq／11、G12／13,参与心肌收缩力、心率、心律和心肌细胞生长的调节。本文着重讨论了心脏G蛋白的分类、结构和功能,以及在心肌肥大、心力衰竭、急性心肌缺血和心律失常等心脏疾病中的改变,以加深对这些疾病的发病机制和病理生理过程的认识。     

溶血磷脂酸受体及其信号转导

溶血磷脂酸(lysophosphatidic acid,LPA)是一种类生长因子的脂类信号分子.在血栓形成过程中被激活的血小板可以产生LPA.自从证明LPA有胞外信号功能以后,许多新的生物活性又被不断发现.LPA最主要的作用是诱导各类细胞增殖.人们已经找到几种LPA受体cDNA克隆.LPA主要通过G蛋白偶联受体影响靶细胞功能,其信号转导系统包括已知的几条信号通路: 激活G_q从而激活磷脂酶C; 激活G_i从而抑制腺苷酸环化酶并激活MAPK级联通路; 激活G_12/13从而激活Rho级联通路等.     

肾上腺素受体研究进展

按照药理学特性及分子克隆情况,肾上腺素受体可分成α１、α２与β亚型,每型又至少可分成三种亚型。肾上腺素受体的分子结构符合Ｇ蛋白耦联膜表面受体的一般特征。采用分子突变技术,已基本明确受体各部分结构的功能。决定与配基结合特性的部位在跨膜区域内,而决定与Ｇ蛋白耦联进引起信号传递的部位主要存在于第三细胞内环。各种亚型受体之间存在着广泛的交互作用,按发生的环节可大致分成四种类型。     

心脏β肾上腺素受体信号转导研究与相关药物研发

β 肾上腺素受体作为重要的 G 蛋白偶联受体家族成员,在血液循环、代谢调节、肌肉收缩和舒张中都具有重要的作用。在心脏中, 急性激活 β 肾上腺素受体能够促进心脏功能,持续性激活 β 肾上腺素受体在心脏重构的病理生理过程中具有重要作用。心脏中的 β 肾上腺 素受体包括 3 个亚型:β1 肾上腺素受体、β2 肾上腺素受体和 β3 肾上腺素受体。文章重点讨论了 β1 和 β2 肾上腺素受体二者在心脏中不同甚 至截然相反的作用。在此基础上,提出基于 β 肾上腺素受体信号转导亚型特异性的心衰治疗新方法。     

与癌症相关的G 蛋白偶联受体及通路的研究进展

G蛋白偶联受体(G protein-coupled receptors,GPCRs)是一类重要的细胞膜表面跨膜蛋白受体超家族,具有7个跨膜螺旋结构。GPCRs的细胞内信号由G蛋白介导,可将激素、神经递质、药物、趋化因子等多种物理和化学的细胞外刺激穿过细胞膜转导到细胞内不同的效应分子,激活相应的信号级联系统进而影响恶性肿瘤的生长迁移过程。虽然目前药物市场上有很多治疗癌症的小分子药物属于G蛋白受体相关药物,但所作用的靶点集中于少数特定G蛋白偶联受体。因此,新的具有成药性的G蛋白偶联受体的开发具有很大的研究价值和市场潜力。本文主要以在癌症发生、发展中起重要作用的溶血磷脂酸(LPA),G蛋白偶联受体30(GPR30)、内皮素A受体(ETAR)等不同G蛋白偶联受体为分类依据,综述其与相关的信号通路在癌症进程中的作用,并对相应的小分子药物的临床应用和研究进展进行展望。     

心脏β_2-肾上腺素受体研究进展

随着受体研究的蓬勃发展 ,对在心脏活动调节中起重要作用的肾上腺素受体的了解也更加深入。近年来的许多研究表明 β 肾上腺素受体不同亚型之间的信号转导及其介导的心脏反应有着很大的差异。本文扼要介绍了心脏 β2 肾上腺素受体的最新研究进展 ,主要包括 β2 肾上腺素受体的混杂G蛋白偶联、信号转导局域化、固有活性及其与充血性心力衰竭的关系。     

Current progress in non-Edg family LPA receptor research

Lysophosphatidic acid (LPA) is the simplest phospholipid yet possesses myriad biological functions. Until 2003, the functions of LPA were thought to be elicited exclusively by three subtypes of the endothelial differentiation gene (Edg) family of G protein-coupled receptors — LPA₁, LPA₂, and LPA₃. However, several biological functions of LPA could not be assigned to any of these receptors indicating the existence of one or more additional LPA receptor(s). More recently, the discovery of a second cluster of LPA receptors which includes LPA₄, LPA₅, and LPA₆ has paved the way for new avenues of LPA research. Analyses of these non-Edg family LPA receptors have begun to fill in gaps to understand biological functions of LPA such as platelet aggregation and vascular development that could not be ascribed to classical Edg family LPA receptors and are also unveiling new biological functions. Here we review recent progress in the non-Edg family LPA receptor research, with special emphasis on the pharmacology, signaling, and physiological roles of this family of receptors. This article is part of a Special Issue entitled Advances in Lysophospholipid Research.     

Non-Edg family LPA receptors: the cutting edge of LPA research

Lysophosphatidic acid (LPA) is a bioactive lipid mediator with diverse physiological and pathological actions on many types of cells. Originally, LPA was thought to elicit its biological functions through three subtypes of endothelial differentiation gene (Edg) family G protein-coupled receptors (LPA1, LPA2 and LPA3) until our group identified a fourth subtype, LPA4. The discovery of this receptor, which is structurally distinct from the Edg family LPA receptors, led to the identification of two additional LPA receptors, LPA5 and LPA6, homologous to LPA4. These 'non-Edg family' LPA receptors now provide a new framework for understanding the diverse functions of LPA, including vascular development, platelet activation and hair growth. In this review, we summarize the identification, intracellular signalling and biological functions of this novel cluster of LPA receptors.     

Lysophosphatidic acid and its role in reproduction

Lysophosphatidic acid (LPA) belongs to a new family of lipid mediators that are endogenous growth factors and that elicit diverse biological effects, usually via the activation of G protein-coupled receptors. LPA can be generated after cell activation through the hydrolysis of preexisting phospholipids in the membranes of stimulated cells. A dramatic elevation of LPA levels was found in serum of patients suffering from ovarian carcinoma. Because these high LPA amounts can be detected as early as stage I of the disease, LPA has been introduced as a new marker for ovarian cancer. Progression of the malignancy is correlated with a differential expression of various LPA receptor subtypes. The presence of LPA in the follicular fluid of healthy individuals implicates that this biological mediator may be relevant to normal ovarian physiology. LPA induces proliferation and mitogenic signaling of prostate cancer cells, and a novel LPA receptor isoform has been recognized in healthy prostate tissues. This evidence indicates multiple roles for LPA in both male and female reproductive physiology and pathology. In this review, we summarize the literature on LPA generation, the way it is degraded, and the mechanisms by which signals are transduced by various LPA receptors in reproductive tissues, and we discuss possible future research directions in these areas.     

Lysophospholipids and their receptors in the central nervous system

Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P), two of the best-studied lysophospholipids, are known to influence diverse biological events, including organismal development as well as function and pathogenesis within multiple organ systems. These functional roles are due to a family of at least 11 G protein-coupled receptors (GPCRs), named LPA_1–6 and S1P_1–5, which are widely distributed throughout the body and that activate multiple effector pathways initiated by a range of heterotrimeric G proteins including G_i/o, G_12/13, G_q and G_s, with actual activation dependent on receptor subtypes. In the central nervous system (CNS), a major locus for these signaling pathways, LPA and S1P have been shown to influence myriad responses in neurons and glial cell types through their cognate receptors. These receptor-mediated activities can contribute to disease pathogenesis and have therapeutic relevance to human CNS disorders as demonstrated for multiple sclerosis (MS) and possibly others that include congenital hydrocephalus, ischemic stroke, neurotrauma, neuropsychiatric disorders, developmental disorders, seizures, hearing loss, and Sandhoff disease, based upon the experimental literature. In particular, FTY720 (fingolimod, Gilenya, Novartis Pharma, AG) that becomes an analog of S1P upon phosphorylation, was approved by the FDA in 2010 as a first oral treatment for MS, validating this class of receptors as medicinal targets. This review will provide an overview and update on the biological functions of LPA and S1P signaling in the CNS, with a focus on results from studies using genetic null mutants for LPA and S1P receptors. This article is part of a Special Issue entitled Advances in Lysophospholipid Research.     

LPA4/p2y9/GPR23 mediates rho-dependent morphological changes in a rat neuronal cell line

Lysophosphatidic acid (LPA) is a potent lipid mediator that evokes a variety of biological responses in many cell types via its specific G protein-coupled receptors. In particular, LPA affects cell morphology, cell survival, and cell cycle progression in neuronal cells. Recently, we identified p2y(9)/GPR23 as a novel fourth LPA receptor, LPA(4) (Noguchi, K., Ishii, S., and Shimizu, T. (2003) J. Biol. Chem. 278, 25600-25606). To assess the functions of LPA(4) in neuronal cells, we used rat neuroblastoma B103 cells that lack endogenous responses to LPA. In B103 cells stably expressing LPA(4), we observed G(q/11)-dependent calcium mobilization, but LPA did not affect adenylyl cyclase activity. In LPA(4) transfectants, LPA induced dramatic morphological changes, i.e. neurite retraction, cell aggregation, and cadherin-dependent cell adhesion, which involved Rho-mediated signaling pathways. Thus, our results demonstrated that LPA(4) as well as LPA(1) couple to G(q/11) and G(12/13), whereas LPA(4) differs from LPA(1) in that it does not couple to G(i/o). Through neurite retraction and cell aggregation, LPA(4) may play a role in neuronal development such as neurogenesis and neuronal migration.     

Thematic Review Series: Lysophospholipids And Their Receptors: LPA receptor signaling: pharmacology,physiology, and pathophysiology

Lysophosphatidic acid (LPA) is a small ubiquitous lipid found in vertebrate and nonvertebrate organisms that mediates diverse biological actions and demonstrates medicinal relevance. LPA’s functional roles are driven by extracellular signaling through at least six 7-transmembrane G protein-coupled receptors. These receptors are named LPA_1–6 and signal through numerous effector pathways activated by heterotrimeric G proteins, including G_i/o, G_12/13, G_q, and G_s. LPA receptor-mediated effects have been described in numerous cell types and model systems, both in vitro and in vivo, through gain- and loss-of-function studies. These studies have revealed physiological and pathophysiological influences on virtually every organ system and developmental stage of an organism. These include the nervous, cardiovascular, reproductive, and pulmonary systems. Disturbances in normal LPA signaling may contribute to a range of diseases, including neurodevelopmental and neuropsychiatric disorders, pain, cardiovascular disease, bone disorders, fibrosis, cancer, infertility, and obesity. These studies underscore the potential of LPA receptor subtypes and related signaling mechanisms to provide novel therapeutic targets.     

Lysophosphatidic acid as a novel cell survival/apoptotic factor

Lysophosphatidic acid (LPA) activates its cognate G protein-coupled receptors (GPCRs) LPA(1-3) to exert diverse cellular effects, including cell survival and apoptosis. The potent survival effect of LPA on Schwann cells (SCs) is mediated through the pertussis toxin (PTX)-sensitive G(i/o)/phosphoinositide 3-kinase (PI3K)/Akt signaling pathways and possibly enhanced by the activation of PTX-insensitive Rho-dependent pathways. LPA promotes survival of many other cell types mainly through PTX-sensitive G(i/o) proteins. Paradoxically, LPA also induces apoptosis in certain cells, such as myeloid progenitor cells, hippocampal neurons, and PC12 cells, in which the activation of the Rho-dependent pathways and caspase cascades has been implicated. The effects of LPA on both cell survival and apoptosis underscore important roles for this lipid in normal development and pathological processes.     

Lysophosphatidic acid is a lipid mediator with wide range of biological activities. Biosynthetic pathways and mechanism of action

Lysophosphatidic acid (LPA) is a lipid mediator required for maintaining homeostasis of numerous physiological functions and also involved in development of some pathological processes through interactions with G protein-coupled receptors. Recently many data have appeared about the role of this phospholipid in humans, but pathways of LPA biosynthesis and mechanisms of its action remain unclear. This review presents modern concepts about biosynthesis, reception, and biological activity of LPA in humans. Natural and synthetic LPA analogs are considered in the view of their possible use in pharmacology as agonists and/or antagonists of G protein-coupled receptors of LPA.     

Lysophosphatidic acid (LPA) and its receptors: Role in airway inflammation and remodeling

Lysophosphatidic acid (LPA), a simple bioactive phospholipid, is present in biological fluids such as plasma and bronchoalveolar lavage (BAL). It appears to have both pro- and anti-inflammatory roles in inflammatory lung diseases. Exogenous LPA promotes inflammatory responses by regulating the expression of chemokines, cytokines, and cytokine receptors in lung epithelial cells. In addition to the modulation of inflammatory responses, LPA regulates cytoskeleton rearrangement and confers protection against lung injury by enhancing lung epithelial cell barrier integrity and remodeling. The biological effects of LPA are mediated through its cell surface G-protein coupled LPA_1–7 receptors. The roles of LPA receptors in lung fibrosis, asthma, and acute lung injury have been investigated using genetically engineered LPA receptor deficient mice and there appears to be a definitive role for endogenous LPA and its receptors in the pathogenesis of pulmonary inflammatory diseases. This review summarizes recent reports on the role of LPA and its receptors in the regulation of lung epithelial inflammatory responses and remodeling. This article is part of a Special Issue entitled: Advances in Lysophospholipid Research.