Search

G protein‐coupled receptors (GPCRs) are a large family of cell surface receptors that play a critical role in nervous system function by transmitting signals between cells and their environment. They are involved in many, if not all, nervous system processes, and their dysfunction has been linked to various neurological disorders representing important drug targets. This overview emphasises the GPCRs of the nervous system, which are the research focus of the members of ERNEST COST action (CA18133) working group ‘Biological roles of signal transduction’. First, the (patho)physiological role of the nervous system GPCRs in the modulation of synapse function is discussed. We then debate the (patho)physiology and pharmacology of opioid, acetylcholine, chemokine, melatonin and adhesion GPCRs in the nervous system. Finally, we address the orphan GPCRs, their implication in the nervous system function and disease, and the challenges that need to be addressed to deorphanize them. [ABSTRACT FROM AUTHOR]

The increasing human population, combined with low inefficiency and adverse effects of available pesticides, has magnified the urgent need of developing next‐generation pesticides. Among the available approaches, strategies targeting invertebrate G protein‐coupled receptors (GPCRs) are very promising as these receptors are the targets of endogenous neuropeptides/neuromodulators that upon binding to their receptors induce profound changes in insect physiology. Therefore, exploring GPCR regulators has great potential in the development of targeted next‐generation pesticides. Despite the great potential of such alternative pesticides, so far there has been only one approved compound, Amitraz, which conveys its anti‐pest activity via the GPCR Octopamine receptor. Here, we review the current status of pesticide development, hazards associated with conventional pesticide compounds, alternative strategies that involve next‐generation of pesticides, structural features of GPCRs, and opportunities and challenges of targeting the members of this superfamily in invertebrates to develop anti‐pest agents. In conclusion, we emphasize that the potential of GPCRs cannot be utilized in full without more genomic and transcriptomic data to improve our understanding of the complex network of peptidergic signaling pathways. We argue how vital it is to obtain three‐dimensional (3D) structural data on physiologically important target GPCRs and encourage the readers to use the state of the art in silico methods such as virtual screening for the discovery of new pesticide compounds. [ABSTRACT FROM AUTHOR]

G protein-coupled receptors (GPCRs) are 7-transmembrane proteins that transduce various extracellular signals into intracellular pathways. They are the major target of neuropeptides, which regulate the development, feeding behavior, mating behavior, circadian rhythm, and many other physiological functions of insects. In the present study, we performed RNA sequencing and de novo transcriptome assembly to uncover the GPCRs expressed in the stick insect Carausius morosus. The transcript assemblies were predicted for the presence of 7-transmembrane GPCR domains. As a result, 430 putative GPCR transcripts were obtained and 43 of these revealed full-length sequences with highly significant similarity to known GPCR sequences in the databases. Thirteen different GPCRs were chosen for tissue expression analysis. Some of these receptors, such as calcitonin, inotocin, and tyramine receptors, showed specific expression in some of the tissues. Additionally, GPCR prediction yielded a novel uncharacterized GPCR sequence, which was specifically expressed in the central nervous system and ganglia. Previously, the only information about the anatomy of the stick insect was on its gastrointestinal system. This study provides complete anatomical information about the adult insect. [ABSTRACT FROM AUTHOR]

BRI3 (brain protein I3) is one of the Wnt/β-catenin pathway target genes as indicated by the results of serial analysis of gene expression (SAGE) and microarray analyses performed in our laboratory. The Wnt/β-catenin signaling pathway is an evolutionarily conserved pathway, which has important functions in early vertebrate development, axis formation, cellular proliferation, and morphogenesis. Previous studies showed that BRI3 expression is upregulated at both mRNA and protein levels upon β-catenin activation by various approaches, such as lithium treatment and overexpression of Wnt ligands in Huh7 (hepatocellular carcinoma) cell lines. Moreover, with regard to the previous literature, BRI3 was found to have a very important role in the TNFa-mediated cell death pathway. In this study, we screened a human liver cDNA library by yeast two-hybrid assay using BRI3 protein as bait, with the aim of finding novel interaction partners of BRI3. Library screening by yeast mating resulted in the identification of three candidate positive clones. Among these, IFITM3 and MGAT1 proteins were confirmed as interaction partners by using cotransformation in yeast cells and coimmunoprecipitation from mammalian cell lines. Considering the poor functional characterization of BRI3 to date, identification of novel BRI3-interacting proteins is an essential first step in determining the action mechanism of BRI3 with respect to the Wnt/β-catenin pathway. [ABSTRACT FROM AUTHOR]

Background: The Wnt/β-catenin signaling pathway is an evolutionary conserved pathway, which has important functions in vertebrate early development, axis formation, cellular proliferation and morphogenesis. Additionally, Wnt/β-catenin signaling pathway is one of the most important intracellular pathways that controls cancer progression. To date most of the identified targets of this pathway are shown to harbor tumorigenic properties. We previously showed that Mannosyl glycoprotein acetylglucosaminyl-transferase (MGAT1) enzyme is among the Wnt/β-catenin signaling putative target genes in hepatocellular carcinoma cell lines (Huh7).Methods: MGAT1 protein levels were determined by Western Blotting from Huh7 cell lines in which Wnt/β-catenin pathway was activated by means of different approaches such as LiCl treatment and mutant β-catenin overexpression. Luciferase reporter assay was used to analyze the promoter activity of MGAT1. The mRNA levels of MGAT1 were determined by quantitative real-time PCR from Huh7 cells that were treated with either Wnt agonist or GSK-3β inhibitor. Wound healing and XTT cell proliferation assays were performed in order to determine the proliferation and migration capacities of MGAT1 overexpressing stable Huh7 cells. Finally, xenograft experiments were carried out to measure the tumor formation capacities in vivo.Results: In this study we showed that the activation of Wnt/β-catenin pathway culminates in the upregulation of MGAT1 enzyme both at transcriptional and post-transcriptional levels. We also showed that overexpression of the β-catenin gene (CTNNB1) increased the promoter activity of MGAT1. We applied a set of complementary approaches to elucidate the functional importance of MGAT1 as a vital target of Wnt/β-catenin signaling in Huh7 cells. Our analyses related to cell proliferation and migration assays showed that in comparison to the control cells, MGAT1 expressing Huh7 cells have greater proliferative and invasive capabilities. Furthermore, the stable overexpression of MGAT1 gene in Huh7 cell lines lead to a significant increase in tumor growth rate in Severe Combined Immunodeficient (SCID) mice.Conclusions: Taken together, we showed for the first time that MGAT is a novel Wnt/β-catenin pathway target that has important implications for tumorigenesis. [ABSTRACT FROM AUTHOR]

Abstract: The Wnt signaling pathway is involved in many differentiation events during embryonic development and can lead to tumor formation after aberrant activation of its components. β-catenin, a cytoplasmic component, plays a major role in the transduction of canonical Wnt signaling. The aim of this study was to identify novel genes that are regulated by active β-catenin/TCF signaling in hepatocellular carcinoma-derived Huh7 cells with high (transfected) and low β-catenin/TCF activities. High TCF activity Huh7 cells led to earlier and larger tumor formation when xenografted into nude mice. SAGE (Serial Analysis of Gene Expression), genome-wide microarray and in silico promoter analysis were performed in parallel, to compare gene expression between low and high β-catenin/TCF activity clones, and also those that had been rescued from the xenograft tumors. SAGE and genome-wide microarray data were compared and contrasted. BRI3 and HSF2 were identified as novel targets of Wnt/β-catenin signaling after combined analysis and confirming experiments including qRT-PCR, ChIP, luciferase assay and lithium treatment. [Copyright &y& Elsevier]

Allatostatins (AST) are neuropeptides with variable function ranging from regulation of developmental processes to the feeding behavior in insects. They exert their effects by binding to cognate GPCRs, called Allatostatin receptors (AlstR), which emerge as promising targets for pesticide design. However, AlstRs are rarely studied. This study is the first reported structural study on AlstR-AST interaction. In this work, the first C type AlstR from the stick insect Carausius morosus (CamAlstR-C) was identified and its interaction with type C AST peptide was shown to be physically consistent with the experimental results. The proposed structure of CamAlstR-C revealed a conserved motif within the third extracellular loop, which, together with the N-terminus is essential for ligand binding. In this work, computational studies were combined with molecular and nano-scale approaches in order to introduce an unknown GPCR-ligand system. Consequently, the data obtained provided a reliable target region for future agonist/inverse agonist studies on AlstRs. [ABSTRACT FROM AUTHOR]