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McCulloch KJ, Babonis LS, Liu A, Daly CM, Martindale MQ, Koenig KM. Nematostella vectensis exemplifies the exceptional expansion and diversity of opsins in the eyeless Hexacorallia. EvoDevo 2023; 14:14. [PMID: 37735470 PMCID: PMC10512536 DOI: 10.1186/s13227-023-00218-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 09/11/2023] [Indexed: 09/23/2023] Open
Abstract
BACKGROUND Opsins are the primary proteins responsible for light detection in animals. Cnidarians (jellyfish, sea anemones, corals) have diverse visual systems that have evolved in parallel with bilaterians (squid, flies, fish) for hundreds of millions of years. Medusozoans (e.g., jellyfish, hydroids) have evolved eyes multiple times, each time independently incorporating distinct opsin orthologs. Anthozoans (e.g., corals, sea anemones,) have diverse light-mediated behaviors and, despite being eyeless, exhibit more extensive opsin duplications than medusozoans. To better understand the evolution of photosensitivity in animals without eyes, we increased anthozoan representation in the phylogeny of animal opsins and investigated the large but poorly characterized opsin family in the sea anemone Nematostella vectensis. RESULTS We analyzed genomic and transcriptomic data from 16 species of cnidarians to generate a large opsin phylogeny (708 sequences) with the largest sampling of anthozoan sequences to date. We identified 29 opsins from N. vectensis (NvOpsins) with high confidence, using transcriptomic and genomic datasets. We found that lineage-specific opsin duplications are common across Cnidaria, with anthozoan lineages exhibiting among the highest numbers of opsins in animals. To establish putative photosensory function of NvOpsins, we identified canonically conserved protein domains and amino acid sequences essential for opsin function in other animal species. We show high sequence diversity among NvOpsins at sites important for photoreception and transduction, suggesting potentially diverse functions. We further examined the spatiotemporal expression of NvOpsins and found both dynamic expression of opsins during embryonic development and sexually dimorphic opsin expression in adults. CONCLUSIONS These data show that lineage-specific duplication and divergence has led to expansive diversity of opsins in eyeless cnidarians, suggesting opsins from these animals may exhibit novel biochemical functions. The variable expression patterns of opsins in N. vectensis suggest opsin gene duplications allowed for a radiation of unique sensory cell types with tissue- and stage-specific functions. This diffuse network of distinct sensory cell types could be an adaptive solution for varied sensory tasks experienced in distinct life history stages in Anthozoans.
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Affiliation(s)
- Kyle J McCulloch
- Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, MN, 55108, USA
| | - Leslie S Babonis
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14853, USA
- Whitney Lab for Marine Bioscience, University of Florida, St. Augustine, FL, 32080, USA
| | - Alicia Liu
- John Harvard Distinguished Science Fellowship Program, Harvard University, Cambridge, MA , 02138, , USA
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Christina M Daly
- John Harvard Distinguished Science Fellowship Program, Harvard University, Cambridge, MA , 02138, , USA
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Mark Q Martindale
- Whitney Lab for Marine Bioscience, University of Florida, St. Augustine, FL, 32080, USA
| | - Kristen M Koenig
- John Harvard Distinguished Science Fellowship Program, Harvard University, Cambridge, MA , 02138, , USA.
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA.
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA.
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Sharker MR, Sukhan ZP, Kim SC, Lee WK, Kho KH. Molecular Identification, Characterization, and Expression Analysis of a Gonadotropin-Releasing Hormone Receptor (GnRH-R) in Pacific Abalone, Haliotis discus hannai. Molecules 2020; 25:molecules25122733. [PMID: 32545589 PMCID: PMC7355911 DOI: 10.3390/molecules25122733] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 06/02/2020] [Accepted: 06/11/2020] [Indexed: 12/24/2022] Open
Abstract
A full-length cDNA sequence encoding a GnRH receptor was cloned from the pleuropedal ganglion of the Pacific abalone, Haliotis discus hannai. The cloned sequence is 1499-bp in length encoding a protein of 460 amino acid residues, with a molecular mass of 52.22 kDa and an isoelectric point (pI) of 9.57. The architecture of HdhGnRH-R gene exhibited key features of G protein-coupled receptors (GPCRs), including seven membrane spanning domains, putative N-linked glycosylation motifs, and phosphorylation sites of serine and threonine residues. It shared 63%, 52%, and 30% sequence identities with Octopus vulgaris, Limulus polyphemus, and Mizuhopecten yessoensis GnRH-R II sequences, respectively. Phylogenetic analysis indicated that HdhGnRH-R gene was clustered with GnRH-R II of O. vulgaris and O. bimaculoides. qPCR assay demonstrated that the mRNA expression level of this receptor was significantly higher in the pleuropedal ganglion than that in any other examined tissue. Transcriptional activities of this gene in gonadal tissues were significantly higher in the ripening stage. The mRNA expression of this gene was significantly higher in pleuropedal ganglion, testis, and ovary at higher effective accumulative temperature (1000 °C). In situ hybridization revealed that HdhGnRH-R mRNA was expressed in neurosecretory cells of pleuropedal ganglion. Our results suggest that HdhGnRH-R gene synthesized in the neural ganglia might be involved in the control of gonadal maturation and gametogenesis of H. discus hannai. This is the first report of GnRH-R in H. discus hannai and the results may contribute to further studies of GPCRs evolution or may useful for the development of aquaculture method of this abalone species.
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Affiliation(s)
| | | | | | | | - Kang Hee Kho
- Correspondence: ; Tel.: +82-616-597-168; Fax: +82-616-597-169
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Identification, characterization, and expression analysis of a serotonin receptor involved in the reproductive process of the Pacific abalone, Haliotis discus hannai. Mol Biol Rep 2019; 47:555-567. [PMID: 31696430 DOI: 10.1007/s11033-019-05162-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 10/23/2019] [Indexed: 10/25/2022]
Abstract
Serotonin receptor (5-HT) is a biogenic amine acting as a neurotransmitter and neuromodulator that mediates various aspects of reproduction and gametogenesis. The full-length nucleotide sequence of Haliotis discus hannai encodes a protein of 417 amino acids with a predicted molecular mass of 46.54 kDa and isoelectric point of 8.94. The structural profile of 5-HTHdh displayed key features of G protein-coupled receptors, including seven hydrophobic transmembrane domains, putative N-linked glycosylation sites, and several phosphorylation consensus motifs. It shares the highest homology of its amino acid sequence with the 5-HT receptor from Haliotis asinina, and to lesser extent of human 5-HT receptor. The cloned sequence possesses two cysteine residues (Cys-115 and Cys-193), which are likely to form a disulfide bond. Phylogenetic comparison with other known 5-HT receptor genes revealed that the 5-HTHdh is most closely related to the 5-HTHa receptor. The three-dimensional structure of the 5-HTHdh showed multiple alpha helices which is separated by a helix-loop-helix (HLH) structure. Quantitative PCR demonstrated that the receptor mRNA was predominantly expressed in the pleuropedal ganglion. Significant differences in the transcriptional activity of the 5-HTHdh gene were observed in the ovary at the ripening stage. An exclusive expression was detected in pleuropedal ganglion, testis, and ovary at higher effective accumulative temperature (1000 °C). In situ hybridization showed that the 5-HTHdh expressing neurosecretory cells were distributed in the cortex of the pleuropedal ganglion. Our results suggest that 5-HTHdh synthesized in the neural ganglia may be involved in oocyte maturation and spawning of H. discus hannai.
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Interactions between carboxypeptidase M and kinin B1 receptor in endothelial cells. Inflamm Res 2019; 68:845-855. [DOI: 10.1007/s00011-019-01264-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Revised: 05/03/2019] [Accepted: 06/13/2019] [Indexed: 11/25/2022] Open
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Xu Y, Chen Y, Li N, Hu X, Li G, Ding Y, Li J, Shen Y, Wang X, Wang J. Novel compound heterozygous variants in the LHCGR gene identified in a subject with Leydig cell hypoplasia type 1. J Pediatr Endocrinol Metab 2018; 31:239-245. [PMID: 29305568 DOI: 10.1515/jpem-2016-0445] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 11/17/2017] [Indexed: 12/20/2022]
Abstract
BACKGROUND Leydig cell hypoplasia (LCH) is a rare disease and one of the causes of male disorder of sexual differentiation (DSD). Inactivating mutations in the luteinizing hormone/chorionic gonadotropin receptor (LHCGR) gene account for the underlying LCH pathogenicity. This study aimed to analyze the clinical presentation and diagnosis as well as highlight the molecular characteristics of a subject with LCH type 1. CASE PRESENTATION Clinical data were collected from the subject and analyzed. Next generation sequencing of the immediate family pedigree using peripheral blood genomic DNA was performed, and the relevant mutations were verified with Sanger sequencing. We describe the case of a 5-year-old patient with DSD, presenting with a lateral inguinal hernia accompanied by abnormal hormone tests. The genetic analysis revealed novel compound heterozygous variants in the LHCGR gene, including a splice site mutation (c.681-1 G>A) and a frameshift variant (c.1582_1585del ATAT, p.Ile528*). CONCLUSIONS We identified novel compound heterozygous variants in the LHCGR gene, and expanded the genotype-phenotype correlation spectrum of LHCGR variants.
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Affiliation(s)
- Yufei Xu
- Department of Medical Genetics and Molecular Diagnostic Laboratory, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China
| | - Yulin Chen
- Department of Medical Genetics and Molecular Diagnostic Laboratory, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China
| | - Niu Li
- Department of Medical Genetics and Molecular Diagnostic Laboratory, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China
| | - Xuyun Hu
- Department of Medical Genetics and Molecular Diagnostic Laboratory, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China
| | - Guoqiang Li
- Department of Medical Genetics and Molecular Diagnostic Laboratory, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China
| | - Yu Ding
- Department of Endocrinology and Metabolism, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China
| | - Juan Li
- Department of Endocrinology and Metabolism, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China
| | - Yiping Shen
- Department of Medical Genetics and Molecular Diagnostic Laboratory, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China.,Department of Laboratory Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Xiumin Wang
- Department of Endocrinology and Metabolism, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China
| | - Jian Wang
- Department of Medical Genetics and Molecular Diagnostic Laboratory, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China
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Reinl EL, Goodwin ZA, Raghuraman N, Lee GY, Jo EY, Gezahegn BM, Pillai MK, Cahill AG, de Guzman Strong C, England SK. Novel oxytocin receptor variants in laboring women requiring high doses of oxytocin. Am J Obstet Gynecol 2017; 217:214.e1-214.e8. [PMID: 28456503 DOI: 10.1016/j.ajog.2017.04.036] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 04/09/2017] [Accepted: 04/19/2017] [Indexed: 02/06/2023]
Abstract
BACKGROUND Although oxytocin commonly is used to augment or induce labor, it is difficult to predict its effectiveness because oxytocin dose requirements vary significantly among women. One possibility is that women requiring high or low doses of oxytocin have variations in the oxytocin receptor gene. OBJECTIVES To identify oxytocin receptor gene variants in laboring women with low and high oxytocin dosage requirements. STUDY DESIGN Term, nulliparous women requiring oxytocin doses of ≤4 mU/min (low-dose-requiring, n = 83) or ≥20 mU/min (high-dose-requiring, n = 104) for labor augmentation or induction provided consent to a postpartum blood draw as a source of genomic DNA. Targeted-amplicon sequencing (coverage >30×) with MiSeq (Illumina) was performed to discover variants in the coding exons of the oxytocin receptor gene. Baseline relevant clinical history, outcomes, demographics, and oxytocin receptor gene sequence variants and their allele frequencies were compared between low-dose-requiring and high-dose-requiring women. The Scale-Invariant Feature Transform algorithm was used to predict the effect of variants on oxytocin receptor function. The Fisher exact or χ2 tests were used for categorical variables, and Student t tests or Wilcoxon rank sum tests were used for continuous variables. A P value < .05 was considered statistically significant. RESULTS The high-dose-requiring women had greater rates of obesity and diabetes and were more likely to have undergone labor induction and required prostaglandins. High-dose-requiring women were more likely to undergo cesarean delivery for first-stage arrest and less likely to undergo cesarean delivery for nonreassuring fetal status. Targeted sequencing of the oxytocin receptor gene in the total cohort (n = 187) revealed 30 distinct coding variants: 17 nonsynonymous, 11 synonymous, and 2 small structural variants. One novel variant (A243T) was found in both the low- and high-dose-requiring groups. Three novel variants (Y106H, A240_A249del, and P197delfs*206) resulting in an amino acid substitution, loss of 9 amino acids, and a frameshift stop mutation, respectively, were identified only in low-dose-requiring women. Nine nonsynonymous variants were unique to the high-dose-requiring group. These included 3 known variants (R151C, G221S, and W228C) and 6 novel variants (M133V, R150L, H173R, A248V, G253R, and I266V). Of these, R150L, R151C, and H173R were predicted by Scale-Invariant Feature Transform algorithm to damage oxytocin receptor function. There was no statistically significant association between the numbers of synonymous and nonsynonymous substitutions in the patient groups. CONCLUSION Obesity, diabetes, and labor induction were associated with the requirement for high doses of oxytocin. We did not identify significant differences in the prevalence of oxytocin receptor variants between low-dose-requiring and high-dose-requiring women, but novel oxytocin receptor variants were enriched in the high-dose-requiring women. We also found 3 oxytocin receptor variants (2 novel, 1 known) that were predicted to damage oxytocin receptor function and would likely increase an individual's risk for requiring a high oxytocin dose. Further investigation of oxytocin receptor variants and their effects on protein function will inform precision medicine in pregnant women.
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Affiliation(s)
- Erin L Reinl
- Department of Obstetrics and Gynecology, Center for Reproductive Health Sciences, Washington University in St. Louis, School of Medicine, St. Louis, MO
| | - Zane A Goodwin
- Division of Dermatology, Center for Pharmacogenomics, Center for the Study of Itch, Department of Medicine, Washington University in St. Louis, School of Medicine, St. Louis, MO
| | - Nandini Raghuraman
- Department of Obstetrics and Gynecology, Center for Reproductive Health Sciences, Washington University in St. Louis, School of Medicine, St. Louis, MO
| | - Grace Y Lee
- Department of Obstetrics and Gynecology, Center for Reproductive Health Sciences, Washington University in St. Louis, School of Medicine, St. Louis, MO
| | - Erin Y Jo
- Department of Obstetrics and Gynecology, Center for Reproductive Health Sciences, Washington University in St. Louis, School of Medicine, St. Louis, MO
| | - Beakal M Gezahegn
- Department of Obstetrics and Gynecology, Center for Reproductive Health Sciences, Washington University in St. Louis, School of Medicine, St. Louis, MO
| | - Meghan K Pillai
- Department of Obstetrics and Gynecology, Center for Reproductive Health Sciences, Washington University in St. Louis, School of Medicine, St. Louis, MO
| | - Alison G Cahill
- Department of Obstetrics and Gynecology, Washington University in St. Louis, School of Medicine, St. Louis, MO
| | - Cristina de Guzman Strong
- Division of Dermatology, Center for Pharmacogenomics, Center for the Study of Itch, Department of Medicine, Washington University in St. Louis, School of Medicine, St. Louis, MO
| | - Sarah K England
- Department of Obstetrics and Gynecology, Center for Reproductive Health Sciences, Washington University in St. Louis, School of Medicine, St. Louis, MO.
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7
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Niss Arfelt K, Fares S, Sparre-Ulrich AH, Hjortø GM, Gasbjerg LS, Mølleskov-Jensen AS, Benned-Jensen T, Rosenkilde MM. Signaling via G proteins mediates tumorigenic effects of GPR87. Cell Signal 2016; 30:9-18. [PMID: 27865873 DOI: 10.1016/j.cellsig.2016.11.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 11/12/2016] [Accepted: 11/12/2016] [Indexed: 12/16/2022]
Abstract
G protein-coupled receptors (GPCRs) constitute a large protein family of seven transmembrane (7TM) spanning proteins that regulate multiple physiological functions. GPR87 is overexpressed in several cancers and plays a role in tumor cell survival. Here, the basal activity of GPR87 was investigated in transiently transfected HEK293 cells, revealing ligand-independent coupling to Gαi, Gαq and Gα12/13. Furthermore, GPR87 showed a ligand-independent G protein-dependent activation of the downstream transcription factors CREB, NFκB, NFAT and SRE. In tetracycline-induced Flp-In T-Rex-293 cells, GPR87 induced cell clustering presumably through Gα12/13 coupling. In a foci formation assay using retrovirally transduced NIH3T3 cells, GPR87 showed a strong in vitro transforming potential, which correlated to the in vivo tumor induction in nude mice. Importantly, we demonstrate that the transforming potential of GPR87 was correlated to the receptor signaling, as the signaling-impaired mutant R139A (Arg in the conserved "DRY"-motif at the bottom of transmembrane helix 3 of GPR87 substituted to Ala) showed a lower in vitro cell transformation potential. Furthermore, R139A lost the ability to induce cell clustering. In summary, we show that GPR87 is active through several signaling pathways and that the signaling activity is linked to the receptor-induced cell transformation and clustering. The robust surface expression of GPR87 and general high druggability of GPCRs make GPR87 an attractive future anticancer target for drugs that - through inhibition of the receptor signaling - will inhibit its transforming properties.
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Affiliation(s)
- Kristine Niss Arfelt
- Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Suzan Fares
- Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Alexander H Sparre-Ulrich
- Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Gertrud M Hjortø
- Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lærke S Gasbjerg
- Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ann-Sofie Mølleskov-Jensen
- Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Tau Benned-Jensen
- Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mette M Rosenkilde
- Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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Abel S, Geltinger B, Heinrich N, Michl D, Klose A, Beyermann M, Schwarzer D. Semisynthesis and optimization of G protein-coupled receptor mimics. J Pept Sci 2014; 20:831-6. [PMID: 25092519 DOI: 10.1002/psc.2680] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 06/07/2014] [Accepted: 07/09/2014] [Indexed: 11/11/2022]
Abstract
We have recently developed a soluble mimic of the corticotropin-releasing factor receptor type 1 (CRF1), a membrane-spanning G protein-coupled receptor, which allowed investigations on receptor-ligand interactions. The CRF1 mimic consists of the receptor N-terminus and three synthetic extracellular loops (ECL1-3), which constitute the extracellular receptor domains (ECDs) of CRF1, coupled to a linear peptide template. Here, we report the synthesis of a modified CRF1 mimic, which is more similar to the native receptor possessing a cyclic template that displays the ECDs in a more physiological conformation compared with the initial linear design. In order to facilitate detailed biophysical investigations on CRF1 mimics, we have further established a cost-efficient access to the CRF1 mimic, which is suitable for isotopic labeling for NMR spectroscopy. To this end, the loop-mimicking cyclic peptide of the ECL2 of CRF1 was produced recombinantly and cyclized by expressed protein ligation. Cyclic ECL2 was obtained in milligram scale, and CRF1 mimics synthesized from this material displayed the same binding properties as synthetic CRF1 constructs.
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Affiliation(s)
- Sabine Abel
- Department of Chemical Biology, Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Roessle-Str. 10, 13125, Berlin, Germany
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van der Kant R, Vriend G. Alpha-bulges in G protein-coupled receptors. Int J Mol Sci 2014; 15:7841-64. [PMID: 24806342 PMCID: PMC4057707 DOI: 10.3390/ijms15057841] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 04/02/2014] [Accepted: 04/09/2014] [Indexed: 12/31/2022] Open
Abstract
Agonist binding is related to a series of motions in G protein-coupled receptors (GPCRs) that result in the separation of transmembrane helices III and VI at their cytosolic ends and subsequent G protein binding. A large number of smaller motions also seem to be associated with activation. Most helices in GPCRs are highly irregular and often contain kinks, with extensive literature already available about the role of prolines in kink formation and the precise function of these kinks. GPCR transmembrane helices also contain many α-bulges. In this article we aim to draw attention to the role of these α-bulges in ligand and G-protein binding, as well as their role in several aspects of the mobility associated with GPCR activation. This mobility includes regularization and translation of helix III in the extracellular direction, a rotation of the entire helix VI, an inward movement of the helices near the extracellular side, and a concerted motion of the cytosolic ends of the helices that makes their orientation appear more circular and that opens up space for the G protein to bind. In several cases, α-bulges either appear or disappear as part of the activation process.
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Affiliation(s)
- Rob van der Kant
- Centre for Molecular and Biomolecular Informatics, Radboud University Medical Centre, Geert Grooteplein 26-28, 6525 GA Nijmegen, The Netherlands.
| | - Gert Vriend
- Centre for Molecular and Biomolecular Informatics, Radboud University Medical Centre, Geert Grooteplein 26-28, 6525 GA Nijmegen, The Netherlands.
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Klos A, Wende E, Wareham KJ, Monk PN. International Union of Basic and Clinical Pharmacology. [corrected]. LXXXVII. Complement peptide C5a, C4a, and C3a receptors. Pharmacol Rev 2013; 65:500-43. [PMID: 23383423 DOI: 10.1124/pr.111.005223] [Citation(s) in RCA: 178] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The activation of the complement cascade, a cornerstone of the innate immune response, produces a number of small (74-77 amino acid) fragments, originally termed anaphylatoxins, that are potent chemoattractants and secretagogues that act on a wide variety of cell types. These fragments, C5a, C4a, and C3a, participate at all levels of the immune response and are also involved in other processes such as neural development and organ regeneration. Their primary function, however, is in inflammation, so they are important targets for the development of antiinflammatory therapies. Only three receptors for complement peptides have been found, but there are no satisfactory antagonists as yet, despite intensive investigation. In humans, there is a single receptor for C3a (C3a receptor), no known receptor for C4a, and two receptors for C5a (C5a₁ receptor and C5a₂ receptor). The most recently characterized receptor, the C5a₂ receptor (previously known as C5L2 or GPR77), has been regarded as a passive binding protein, but signaling activities are now ascribed to it, so we propose that it be formally identified as a receptor and be given a name to reflect this. Here, we describe the complex biology of the complement peptides, introduce a new suggested nomenclature, and review our current knowledge of receptor pharmacology.
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Affiliation(s)
- Andreas Klos
- Department for Medical Microbiology, Medical School Hannover, Hannover, Germany
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11
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Seddon G, Lounnas V, McGuire R, van den Bergh T, Bywater RP, Oliveira L, Vriend G. Drug design for ever, from hype to hope. J Comput Aided Mol Des 2012; 26:137-50. [PMID: 22252446 PMCID: PMC3268973 DOI: 10.1007/s10822-011-9519-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Accepted: 12/05/2011] [Indexed: 01/28/2023]
Abstract
In its first 25 years JCAMD has been disseminating a large number of techniques aimed at finding better medicines faster. These include genetic algorithms, COMFA, QSAR, structure based techniques, homology modelling, high throughput screening, combichem, and dozens more that were a hype in their time and that now are just a useful addition to the drug-designers toolbox. Despite massive efforts throughout academic and industrial drug design research departments, the number of FDA-approved new molecular entities per year stagnates, and the pharmaceutical industry is reorganising accordingly. The recent spate of industrial consolidations and the concomitant move towards outsourcing of research activities requires better integration of all activities along the chain from bench to bedside. The next 25 years will undoubtedly show a series of translational science activities that are aimed at a better communication between all parties involved, from quantum chemistry to bedside and from academia to industry. This will above all include understanding the underlying biological problem and optimal use of all available data.
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Affiliation(s)
| | - V. Lounnas
- CMBI, Radboud University Nijmegen Medical Centre, Geert Grooteplein 26–28, 6525 GA Nijmegen, The Netherlands
| | - R. McGuire
- BioAxis Research, Bergse Heihoek 56, Berghem, 5351 SL The Netherlands
| | - T. van den Bergh
- Bio-Prodict, Dreijenplein 10, 6703 HB Wageningen, The Netherlands
| | | | - L. Oliveira
- Sao Paulo Federal University (UNIFESP), Sao Paulo, Brazil
| | - G. Vriend
- CMBI, Radboud University Nijmegen Medical Centre, Geert Grooteplein 26–28, 6525 GA Nijmegen, The Netherlands
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Fanelli F, De Benedetti PG. Update 1 of: computational modeling approaches to structure-function analysis of G protein-coupled receptors. Chem Rev 2011; 111:PR438-535. [PMID: 22165845 DOI: 10.1021/cr100437t] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Francesca Fanelli
- Dulbecco Telethon Institute, University of Modena and Reggio Emilia, via Campi 183, 41125 Modena, Italy.
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Vroling B, Sanders M, Baakman C, Borrmann A, Verhoeven S, Klomp J, Oliveira L, de Vlieg J, Vriend G. GPCRDB: information system for G protein-coupled receptors. Nucleic Acids Res 2011; 39:D309-19. [PMID: 21045054 PMCID: PMC3013641 DOI: 10.1093/nar/gkq1009] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Accepted: 10/07/2010] [Indexed: 11/14/2022] Open
Abstract
The GPCRDB is a Molecular Class-Specific Information System (MCSIS) that collects, combines, validates and disseminates large amounts of heterogeneous data on G protein-coupled receptors (GPCRs). The GPCRDB contains experimental data on sequences, ligand-binding constants, mutations and oligomers, as well as many different types of computationally derived data such as multiple sequence alignments and homology models. The GPCRDB provides access to the data via a number of different access methods. It offers visualization and analysis tools, and a number of query systems. The data is updated automatically on a monthly basis. The GPCRDB can be found online at http://www.gpcr.org/7tm/.
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Affiliation(s)
- Bas Vroling
- CMBI, NCMLS, Radboud University Nijmegen Medical Centre, Geert Grooteplein Zuid 26-28, 6525 GA Nijmegen, Department of Molecular Design and Informatics, MSD, Molenstraat 110, 5340 BH, Oss, The Netherlands and Department of Biophysics, Escola Paulista de Medicina, Federal University of São Paulo, São Paulo 04023-062, Brazil
| | - Marijn Sanders
- CMBI, NCMLS, Radboud University Nijmegen Medical Centre, Geert Grooteplein Zuid 26-28, 6525 GA Nijmegen, Department of Molecular Design and Informatics, MSD, Molenstraat 110, 5340 BH, Oss, The Netherlands and Department of Biophysics, Escola Paulista de Medicina, Federal University of São Paulo, São Paulo 04023-062, Brazil
| | - Coos Baakman
- CMBI, NCMLS, Radboud University Nijmegen Medical Centre, Geert Grooteplein Zuid 26-28, 6525 GA Nijmegen, Department of Molecular Design and Informatics, MSD, Molenstraat 110, 5340 BH, Oss, The Netherlands and Department of Biophysics, Escola Paulista de Medicina, Federal University of São Paulo, São Paulo 04023-062, Brazil
| | - Annika Borrmann
- CMBI, NCMLS, Radboud University Nijmegen Medical Centre, Geert Grooteplein Zuid 26-28, 6525 GA Nijmegen, Department of Molecular Design and Informatics, MSD, Molenstraat 110, 5340 BH, Oss, The Netherlands and Department of Biophysics, Escola Paulista de Medicina, Federal University of São Paulo, São Paulo 04023-062, Brazil
| | - Stefan Verhoeven
- CMBI, NCMLS, Radboud University Nijmegen Medical Centre, Geert Grooteplein Zuid 26-28, 6525 GA Nijmegen, Department of Molecular Design and Informatics, MSD, Molenstraat 110, 5340 BH, Oss, The Netherlands and Department of Biophysics, Escola Paulista de Medicina, Federal University of São Paulo, São Paulo 04023-062, Brazil
| | - Jan Klomp
- CMBI, NCMLS, Radboud University Nijmegen Medical Centre, Geert Grooteplein Zuid 26-28, 6525 GA Nijmegen, Department of Molecular Design and Informatics, MSD, Molenstraat 110, 5340 BH, Oss, The Netherlands and Department of Biophysics, Escola Paulista de Medicina, Federal University of São Paulo, São Paulo 04023-062, Brazil
| | - Laerte Oliveira
- CMBI, NCMLS, Radboud University Nijmegen Medical Centre, Geert Grooteplein Zuid 26-28, 6525 GA Nijmegen, Department of Molecular Design and Informatics, MSD, Molenstraat 110, 5340 BH, Oss, The Netherlands and Department of Biophysics, Escola Paulista de Medicina, Federal University of São Paulo, São Paulo 04023-062, Brazil
| | - Jacob de Vlieg
- CMBI, NCMLS, Radboud University Nijmegen Medical Centre, Geert Grooteplein Zuid 26-28, 6525 GA Nijmegen, Department of Molecular Design and Informatics, MSD, Molenstraat 110, 5340 BH, Oss, The Netherlands and Department of Biophysics, Escola Paulista de Medicina, Federal University of São Paulo, São Paulo 04023-062, Brazil
| | - Gert Vriend
- CMBI, NCMLS, Radboud University Nijmegen Medical Centre, Geert Grooteplein Zuid 26-28, 6525 GA Nijmegen, Department of Molecular Design and Informatics, MSD, Molenstraat 110, 5340 BH, Oss, The Netherlands and Department of Biophysics, Escola Paulista de Medicina, Federal University of São Paulo, São Paulo 04023-062, Brazil
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Luchetti F, Canonico B, Betti M, Arcangeletti M, Pilolli F, Piroddi M, Canesi L, Papa S, Galli F. Melatonin signaling and cell protection function. FASEB J 2010; 24:3603-24. [PMID: 20534884 DOI: 10.1096/fj.10-154450] [Citation(s) in RCA: 249] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Besides its well-known regulatory role on circadian rhythm, the pineal gland hormone melatonin has other biological functions and a distinct metabolism in various cell types and peripheral tissues. In different tissues and organs, melatonin has been described to act as a paracrine and also as an intracrine and autocrine agent with overall homeostatic functions and pleiotropic effects that include cell protection and prosurvival factor. These latter effects, documented in a number of in vitro and in vivo studies, are sustained through both receptor-dependent and -independent mechanisms that control detoxification and stress response genes, thus conferring protection against a number of xenobiotics and endobiotics produced by acute and chronic noxious stimuli. Redox-sensitive components are included in the cell protection signaling of melatonin and in the resulting transcriptional response that involves the control of NF-κB, AP-1, and Nrf2. By these pathways, melatonin stimulates the expression of antioxidant and detoxification genes, acting in turn as a glutathione system enhancer. A further and converging mechanism of cell protection by this indoleamine described in different models seems to lie in the control of damage and signaling function of mitochondria that involves decreased production of reactive oxygen species and activation of the antiapoptotic and redox-sensitive element Bcl2. Recent evidence suggests that upstream components in this mitochondrial route include the calmodulin pathway with its central role in melatonin signaling and the survival-promoting component of MAPKs, ERK1/2. In this review article, we will discuss these and other molecular aspects of melatonin signaling relevant to cell protection and survival mechanisms.
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Affiliation(s)
- Francesca Luchetti
- Dipartimento di Scienze Dell’Uomo dell’Ambiente e della Natura, Università degli Studi di Urbino Carlo Bo, Urbino, Italy
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15
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Nishimura K, Unemura K, Tsushima J, Yamauchi Y, Otomo J, Taniguchi T, Kaneko S, Agata K, Kitamura Y. Identification of a novel planarian G-protein-coupled receptor that responds to serotonin in Xenopus laevis oocytes. Biol Pharm Bull 2010; 32:1672-7. [PMID: 19801826 DOI: 10.1248/bpb.32.1672] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Planarians are useful animals for regenerative and neuroscience research at the molecular level. Previously, we have reported the distribution and function of neurotransmitter-synthesizing neurons in the planarian central nervous system. In order to understand the neural projections and connections, it is important to understand the distribution of neurotransmitter receptors. In this study, we isolated a serotonin receptor gene and named it DjSER-7 (Dugesia japonica serotonin receptor type 7). DjSER-7-expressing cells were distributed in the planarian brain. According to electrophysiological analysis using Xenopus oocytes, current response was detected upon exposure to serotonin, but not other neurotransmitters in oocytes that were co-injected with mRNAs of both DjSER-7 and Galpha chimera B-2, which can interact with either Gq-, Gs- or Gi-coupled receptor. In contrast, current response was not detected after exposure to neurotransmitters in oocytes injected with only DjSER-7 mRNA. Our results indicated that DjSER-7 responds to serotonin, as indicated by electrophysiological analysis using Xenopus oocytes.
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Affiliation(s)
- Kaneyasu Nishimura
- Department of Neurobiology, Kyoto Pharmaceutical University, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan
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16
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Kawauchi H, Sower SA, Moriyama S. Chapter 5 The Neuroendocrine Regulation of Prolactin and Somatolactin Secretion in Fish. FISH PHYSIOLOGY 2009. [DOI: 10.1016/s1546-5098(09)28005-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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17
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Chung TT, Webb TR, Chan LF, Cooray SN, Metherell LA, King PJ, Chapple JP, Clark AJL. The majority of adrenocorticotropin receptor (melanocortin 2 receptor) mutations found in familial glucocorticoid deficiency type 1 lead to defective trafficking of the receptor to the cell surface. J Clin Endocrinol Metab 2008; 93:4948-54. [PMID: 18840636 PMCID: PMC2635546 DOI: 10.1210/jc.2008-1744] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
CONTEXT There are at least 24 missense, nonconservative mutations found in the ACTH receptor [melanocortin 2 receptor (MC2R)] that have been associated with the autosomal recessive disease familial glucocorticoid deficiency (FGD) type 1. The characterization of these mutations has been hindered by difficulties in establishing a functional heterologous cell transfection system for MC2R. Recently, the melanocortin 2 receptor accessory protein (MRAP) was identified as essential for the trafficking of MC2R to the cell surface; therefore, a functional characterization of MC2R mutations is now possible. OBJECTIVE Our objective was to elucidate the molecular mechanisms responsible for defective MC2R function in FGD. METHODS Stable cell lines expressing human MRAPalpha were established and transiently transfected with wild-type or mutant MC2R. Functional characterization of mutant MC2R was performed using a cell surface expression assay, a cAMP reporter assay, confocal microscopy, and coimmunoprecipitation of MRAPalpha. RESULTS Two thirds of all MC2R mutations had a significant reduction in cell surface trafficking, even though MRAPalpha interacted with all mutants. Analysis of those mutant receptors that reached the cell surface indicated that four of six failed to signal, after stimulation with ACTH. CONCLUSION The majority of MC2R mutations found in FGD fail to function because they fail to traffic to the cell surface.
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Affiliation(s)
- T T Chung
- Centre for Endocrinology, William Harvey Research Institute, Barts, London EC1M 6BQ, United Kingdom
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18
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Case R, Sharp E, Benned-Jensen T, Rosenkilde MM, Davis-Poynter N, Farrell HE. Functional analysis of the murine cytomegalovirus chemokine receptor homologue M33: ablation of constitutive signaling is associated with an attenuated phenotype in vivo. J Virol 2008; 82:1884-98. [PMID: 18057236 PMCID: PMC2258698 DOI: 10.1128/jvi.02550-06] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2006] [Accepted: 11/20/2007] [Indexed: 01/28/2023] Open
Abstract
The murine cytomegalovirus (MCMV) M33 gene is conserved among all betaherpesviruses and encodes a homologue of seven-transmembrane receptors (7TMR) with the capacity for constitutive signaling. Previous studies have demonstrated that M33 is important for MCMV dissemination to or replication within the salivary glands. In this study, we probed N- and C-terminal regions of M33 as well as known 7TMR signature motifs in transmembrane (TM) II and TM III to determine the impact on cell surface expression, constitutive signaling, and in vivo phenotype. The region between amino acids R(340) and A(353) of the C terminus was found to be important for CREB- and NFAT-mediated signaling, although not essential for phosphatidylinositol turnover. Tagging or truncation of the N terminus of M33 resulted in loss of cell surface expression. Within TM II, an F79D mutation abolished constitutive signaling, demonstrating a role, as in other cellular and viral 7TMR, of TM II in receptor activation. In TM III, the arginine (but not the asparagine) residue of the NRY motif (the counterpart of the common DRY motif in cellular 7TMR) was found to be essential for constitutive signaling. Selected mutations incorporated into recombinant MCMV showed that disruption of constitutive signaling for a viral 7TMR homologue resulted in a reduced capacity to disseminate to or replicate in the salivary glands. In addition, HCMV UL33 was found to partially compensate for the lack of M33 in vivo, suggesting conserved biological roles of the UL33 gene family.
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Affiliation(s)
- Ruth Case
- Clinical Medical Virology Centre, University of Queensland, Sir Albert Sakzewski Virus Research Centre, Royal Children's Hospital, Herston 4029, Queensland, Australia
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19
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Santos EL, Reis RI, Silva RG, Shimuta SI, Pecher C, Bascands JL, Schanstra JP, Oliveira L, Bader M, Paiva ACM, Costa-Neto CM, Pesquero JB. Functional rescue of a defective angiotensin II AT1 receptor mutant by the Mas protooncogene. ACTA ACUST UNITED AC 2007; 141:159-67. [PMID: 17320985 DOI: 10.1016/j.regpep.2006.12.030] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2006] [Revised: 12/23/2006] [Accepted: 12/23/2006] [Indexed: 11/19/2022]
Abstract
Earlier studies with Mas protooncogene, a member of the G-protein-coupled receptor family, have proposed this gene to code for a functional AngII receptor, however further results did not confirm this assumption. In this work we investigated the hypothesis that a heterodimeration AT(1)/Mas could result in a functional interaction between both receptors. For this purpose, CHO or COS-7 cells were transfected with the wild-type AT(1) receptor, a non-functional AT(1) receptor double mutant (C18F-K20A) and Mas or with WT/Mas and C18F-K20A/Mas. Cells single-expressing Mas or C18F/K20A did not show any binding for AngII. The co-expression of the wild-type AT(1) receptor and Mas showed a binding profile similar to that observed for the wild-type AT(1) expressed alone. Surprisingly, the co-expression of the double mutant C18F/K20A and Mas evoked a total recovery of the binding affinity for AngII to a level similar to that obtained for the wild-type AT(1). Functional measurements using inositol phosphate and extracellular acidification rate assays also showed a clear recovery of activity for AngII on cells co-expressing the mutant C18F/K20A and Mas. In addition, immunofluorescence analysis localized the AT(1) receptor mainly at the plasma membrane and the mutant C18F-K20A exclusively inside the cells. However, the co-expression of C18F-K20A mutant with the Mas changed the distribution pattern of the mutant, with intense signals at the plasma membrane, comparable to those observed in cells expressing the wild-type AT(1) receptor. These results support the hypothesis that Mas is able to rescue binding and functionality of the defective C18F-K20A mutant by dimerization.
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MESH Headings
- Amino Acid Sequence
- Angiotensin II/metabolism
- Animals
- CHO Cells
- COS Cells
- Cell Membrane/metabolism
- Chlorocebus aethiops
- Cricetinae
- Cricetulus
- Fluoresceins
- Fluorescent Antibody Technique, Direct
- Fluorescent Dyes
- Indoles
- Inhibitory Concentration 50
- Inositol Phosphates/analysis
- Inositol Phosphates/metabolism
- Models, Chemical
- Molecular Sequence Data
- Mutation
- Polymerase Chain Reaction
- Proto-Oncogenes/genetics
- Receptor, Angiotensin, Type 1/chemistry
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Transfection
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Affiliation(s)
- Edson L Santos
- Department of Biophysics, Escola Paulista de Medicina, Federal University of São Paulo, 04023-062 São Paulo, SP, Brazil
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20
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Oliveira L, Costa-Neto CM, Nakaie CR, Schreier S, Shimuta SI, Paiva ACM. The Angiotensin II AT1 Receptor Structure-Activity Correlations in the Light of Rhodopsin Structure. Physiol Rev 2007; 87:565-92. [PMID: 17429042 DOI: 10.1152/physrev.00040.2005] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The most prevalent physiological effects of ANG II, the main product of the renin-angiotensin system, are mediated by the AT1 receptor, a rhodopsin-like AGPCR. Numerous studies of the cardiovascular effects of synthetic peptide analogs allowed a detailed mapping of ANG II's structural requirements for receptor binding and activation, which were complemented by site-directed mutagenesis studies on the AT1 receptor to investigate the role of its structure in ligand binding, signal transduction, phosphorylation, binding to arrestins, internalization, desensitization, tachyphylaxis, and other properties. The knowledge of the high-resolution structure of rhodopsin allowed homology modeling of the AT1 receptor. The models thus built and mutagenesis data indicate that physiological (agonist binding) or constitutive (mutated receptor) activation may involve different degrees of expansion of the receptor's central cavity. Residues in ANG II structure seem to control these conformational changes and to dictate the type of cytosolic event elicited during the activation. 1) Agonist aromatic residues (Phe8 and Tyr4) favor the coupling to G protein, and 2) absence of these residues can favor a mechanism leading directly to receptor internalization via phosphorylation by specific kinases of the receptor's COOH-terminal Ser and Thr residues, arrestin binding, and clathrin-dependent coated-pit vesicles. On the other hand, the NH2-terminal residues of the agonists ANG II and [Sar1]-ANG II were found to bind by two distinct modes to the AT1 receptor extracellular site flanked by the COOH-terminal segments of the EC-3 loop and the NH2-terminal domain. Since the [Sar1]-ligand is the most potent molecule to trigger tachyphylaxis in AT1 receptors, it was suggested that its corresponding binding mode might be associated with this special condition of receptors.
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Affiliation(s)
- Laerte Oliveira
- Department of Biophysics, Escola Paulista de Medicina, Federal University of São Paulo, Brazil.
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21
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Rubenstein LA, Zauhar RJ, Lanzara RG. Molecular dynamics of a biophysical model for β2-adrenergic and G protein-coupled receptor activation. J Mol Graph Model 2006; 25:396-409. [PMID: 16574446 DOI: 10.1016/j.jmgm.2006.02.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2005] [Revised: 02/17/2006] [Accepted: 02/21/2006] [Indexed: 11/22/2022]
Abstract
This study analyzes 16 molecular dynamic simulations of a biophysical model for beta(2)-adrenergic (B2AR) and G protein-coupled receptor (GPCR) activation. In this model, a highly conserved cysteine residue, C106 (C3.25 or CysIII:01), provides a free sulfhydryl or thiol group in an acid-base equilibrium between uncharged (RSH) and charged (RS(-)) states that functions as an electrostatic molecular switch for receptor activation. The transition of C106 in the B2AR between acid and base states significantly changes the helical/transmembrane (TM) domain interactions and the electrostatic interaction energy differences (DeltaDeltaE(EL)). The DeltaDeltaE(EL) changes correlate well with the experimentally observed ligand efficacies. The TM interaction energies display patterns compatible with those previously recognized as responsible for GPCR activation. Key differences between the agonist, epinephrine, and the antagonist, pindolol, are seen for the TM3 x 6, TM3 x 4, TM6 x 7 and TM1 x 7 interaction energies. Pindolol also produces a weaker DeltaDeltaE(EL) interaction and less TM interaction energy changes, which are important differences between the agonist and antagonist ligands. The D115E mutant with pindolol displays a greater DeltaDeltaE(EL) and TM interactions than for the wild-type B2AR with pindolol. This explains the higher activity of pindolol in the D115E mutant. The constitutively active D130A mutant displays TM interaction patterns similar to those for the activating ligands implying a common pattern for receptor activation. These findings support the broad concept of protean agonism and demonstrate the potential for allosteric modulation. They also demonstrate that this two-state model agrees with many previous experimental and theoretical observations of GPCRs.
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Affiliation(s)
- Lester A Rubenstein
- Department of Physiology and Biophysics, Mount Sinai School of Medicine, One Gustav Levy Place, New York, NY 10029, USA
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22
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Ongvarrasopone C, Roshorm Y, Somyong S, Pothiratana C, Petchdee S, Tangkhabuanbutra J, Sophasan S, Panyim S. Molecular cloning and functional expression of the Penaeus monodon 5-HT receptor. ACTA ACUST UNITED AC 2006; 1759:328-39. [PMID: 16949686 DOI: 10.1016/j.bbaexp.2006.07.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2005] [Revised: 07/16/2006] [Accepted: 07/24/2006] [Indexed: 10/24/2022]
Abstract
Serotonin (5-HT) mediates a number of diverse physiological functions in crustaceans by interacting with various 5-HT receptor subtypes. A putative 5-HT receptor cloned from the ovary of the black tiger prawn (Penaeus monodon) consisted of 2291 nucleotides, encoding a putative 5-HT(1Pem) receptor protein of 591 amino acids. Transient expression of 5-HT(1Pem) in HEK293 cells demonstrated a saturable [3H]-5-HT binding with a Kd of 10.43+/-1.13 nM and Bmax of 1.53+/-0.06 pmol/mg. The putative 5-HT(1Pem) receptor is expressed in all tissues examined and is constitutively expressed in the ovary during ovarian maturation and spent phase. Polyclonal antibodies against the third intracellular loop (i3 loop) of the 5-HT receptor showed that the 5-HT(1Pem) receptor protein was expressed in the trabeculae of ovarian stages 1 and 2 but on the cortical rod and surrounding the oocyte membrane of stages 3 and 4, suggesting that receptor localization plays a critical role in regulating ovarian maturation and spawning in penaeus shrimp.
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Affiliation(s)
- Chalermporn Ongvarrasopone
- Institute of Molecular Biology and Genetics, Mahidol University (Salaya Campus), 25/25 Phutthamonthon 4 Rd. Salaya, Phutthamonthon district, Nakhon Pathom, 73170, Thailand.
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23
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Ananthanarayanan VS, Kerman A. Role of metal ions in ligand-receptor interaction: insights from structural studies. Mol Cell Endocrinol 2006; 246:53-9. [PMID: 16368180 DOI: 10.1016/j.mce.2005.11.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Experimental data indicate that metal ions such as Na(+), Ca(2+) and Mg(2+), which are present in millimolar concentrations in the extracellular environment, modulate binding of ligands to plasma membrane receptors. Here, we briefly review structural studies that demonstrate that various types of ligands, including peptide hormones and drugs, bind metal ions, in particular Ca(2+), in the lipid milieu. We propose that the metal ion-bound forms of ligands represent their bioactive conformations. With a view to understanding the mechanism of modulation of ligand-receptor interactions by metal ions, we have computed a homology model of the mu-opioid receptor, a G protein-coupled receptor (GPCR), and performed docking of specific agonist and antagonist ligands in the receptor. This resulted in the formation of a ligand-metal ion-receptor (ternary) complex which accounted for the data on the structure-activity relationships of ligands and mutation data on the receptor. Based on experimental and modeling data, we have proposed a general mechanism of activation of GPCRs by their corresponding ligands wherein metal ions play a pivotal role. Studies on overexpressed segments of mu-receptor are in progress to verify the above proposal.
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Affiliation(s)
- Vettai S Ananthanarayanan
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1200 Main St. W., Hamilton, Ont., Canada L8N 3Z5.
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24
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Barbas D, Zappulla JP, Angers S, Bouvier M, Mohamed HA, Byrne JH, Castellucci VF, DesGroseillers L. An aplysia dopamine1-like receptor: molecular and functional characterization. J Neurochem 2005; 96:414-27. [PMID: 16336222 DOI: 10.1111/j.1471-4159.2005.03561.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In Aplysia, the neurotransmitter dopamine is involved in the regulation of various physiological processes and motor functions, like feeding behaviour, and in the siphon-gill withdrawal reflex. In this paper, we report the characterization of the first Aplysia D1-like dopamine receptor (Apdop1) mainly expressed in the CNS, heart and buccal mass. Following expression of the Apdop1 receptor in HEK293 cells, a higher level of cAMP was observed in the absence of the receptor ligand, showing that Apdop1 is constitutively active. This activity was blocked by the inverse agonist flupentixol. Application of dopamine (EC50 of 35 nm) or serotonin (EC50 of 36 microm) to Apdop1-transfected HEK293 cells further increased the level of cAMP, suggesting that the receptor is linked to the stimulatory Gs protein pathway. When expressed in cultured sensory neurons, Apdop1 immunoreactivity was observed in the cell body and neurites. Control sensory neurons responded to dopamine with a decrease in excitability mediated by a pertusis toxin-sensitive G protein. Expression of Apdop1 produced an increase in hyperpolarization in the absence of agonist and an increase in membrane excitability following stimulation by dopamine. In the presence of pertussis toxin to inhibit the Gi protein inhibitory pathway responsible for decrease in excitability mechanism, Stimulation of membrane excitability was observed. Apdop1 sensitivity to dopamine makes it a potential modulator of operant conditioning procedure.
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Affiliation(s)
- Demian Barbas
- Département de biochimie, Université de Montréal, Montréal, Québec, Canada
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25
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Fanelli F, De Benedetti PG. Computational Modeling Approaches to Structure−Function Analysis of G Protein-Coupled Receptors. Chem Rev 2005; 105:3297-351. [PMID: 16159154 DOI: 10.1021/cr000095n] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Francesca Fanelli
- Dulbecco Telethon Institute and Department of Chemistry, University of Modena and Reggio Emilia, via Campi 183, 41100 Modena, Italy.
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26
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Tao Q, Lloyd B, Lang S, Houston D, Zorn A, Wylie C. A novel G protein-coupled receptor, related to GPR4, is required for assembly of the cortical actin skeleton in early Xenopus embryos. Development 2005; 132:2825-36. [PMID: 15930112 DOI: 10.1242/dev.01866] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
As the fertilized Xenopus egg undergoes sequential cell divisions to form a blastula, each cell develops a network of cortical actin that provides shape and skeletal support for the whole embryo. Disruption of this network causes loss of shape and rigidity of the embryo, and disrupts gastrulation movements. We previously showed that lysophosphatidic acid (LPA) signaling controls the change in cortical actin density that occurs at different stages of the cell cycle. Here, we use a gain-of-function screen, using an egg cDNA expression library, to identify an orphan G protein-coupled cell-surface receptor (XFlop) that controls the overall amount of cortical F-actin. Overexpression of XFlop increases the amount of cortical actin, as well as embryo rigidity and wound healing, whereas depletion of maternal XFlop mRNA does the reverse. Both overexpression and depletion of XFlop perturb gastrulation movements. Reciprocal rescue experiments, and comparison of the effects of their depletion in early embryos, show that the XLPA and XFlop signaling pathways play independent roles in cortical actin assembly, and thus that multiple signaling pathways control the actin skeleton in the blastula.
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Affiliation(s)
- Qinghua Tao
- Division of Developmental Biology, Cincinnati Children's Research Foundation, 3333 Burnet Avenue, Cincinnati, OH 45229, USA
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27
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Jongejan A, Bruysters M, Ballesteros JA, Haaksma E, Bakker RA, Pardo L, Leurs R. Linking agonist binding to histamine H1 receptor activation. Nat Chem Biol 2005; 1:98-103. [PMID: 16408006 DOI: 10.1038/nchembio714] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2005] [Accepted: 05/24/2005] [Indexed: 11/09/2022]
Abstract
G protein-coupled receptors (GPCRs) constitute a large and functionally diverse family of transmembrane proteins. They are fundamental in the transfer of extracellular stimuli to intracellular signaling pathways and are among the most targeted proteins in drug discovery. The detailed molecular mechanism for agonist-induced activation of rhodopsin-like GPCRs has not yet been described. Using a combination of site-directed mutagenesis and molecular modeling, we characterized important steps in the activation of the human histamine H1 receptor. Both Ser3.36 and Asn7.45 are important links between histamine binding and previously proposed conformational changes in helices 6 and 7. Ser3.36 acts as a rotamer toggle switch that, upon agonist binding, initiates the activation of the receptor through Asn7.45. The proposed transduction involves specific residues that are conserved among rhodopsin-like GPCRs.
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Affiliation(s)
- Aldo Jongejan
- Leiden/Amsterdam Center for Drug Research, Division of Medicinal Chemistry, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
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28
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Patanè E, Pittalà V, Guerrera F, Salerno L, Romeo G, Siracusa MA, Russo F, Manetti F, Botta M, Mereghetti I, Cagnotto A, Mennini T. Synthesis of 3-Arylpiperazinylalkylpyrrolo[3,2-d]pyrimidine-2,4-dione Derivatives as Novel, Potent, and Selective α1-Adrenoceptor Ligands. J Med Chem 2005; 48:2420-31. [PMID: 15801833 DOI: 10.1021/jm040870h] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Novel compounds characterized by a pyrrolo[3,2-d]pyrimidine-2,4-dione (PPm) system connected through an alkyl chain to a phenylpiperazine (PPz) residue were designed as structural analogues of the alpha(1)-adrenoceptor (alpha(1)-AR) ligand RN5 (1). In this new series of derivatives an arylpyrrolo moiety has replaced the indole nucleus of RN5. Several structural modifications were performed on the PPm and PPz moieties and the connecting alkyl chain. These compounds were synthesized and tested in radioligand binding experiments where many of them showed interesting binding profiles. Some compounds, including 31, 34, and 36, displayed substantial alpha(1)-AR selectivity with respect to serotoninergic 5-HT(1A) and dopaminergic D(1) and D(2) receptors. Two different molecular modeling approaches (pharmacophoric mapping and quantitative structure-affinity relationship analysis) have been applied to rationalize, at a quantitative level, the relationships between affinity toward alpha(1)-ARs and the structure of the studied compounds. Several QSAR models have been reported and described, accounting for the influence of various molecular portions on such affinity data.
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Affiliation(s)
- Emanuele Patanè
- Dipartimento di Scienze Farmaceutiche, Università di Catania, viale A. Doria 6, 95125 Catania, Italy.
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29
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Wang L, Radu CG, Yang LV, Bentolila LA, Riedinger M, Witte ON. Lysophosphatidylcholine-induced surface redistribution regulates signaling of the murine G protein-coupled receptor G2A. Mol Biol Cell 2005; 16:2234-47. [PMID: 15728718 PMCID: PMC1087231 DOI: 10.1091/mbc.e04-12-1044] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Intracellular trafficking and spatial dynamics of membrane receptors critically regulate receptor function. Using microscopic and subcellular fractionation analysis, we studied the localization of the murine G protein-coupled receptor G2A (muG2A). Evaluating green fluorescent protein-tagged, exogenously expressed as well as the endogenous muG2A, we observed that this receptor was spontaneously internalized and accumulated in endosomal compartments, whereas its surface expression was enhanced and stabilized by lysophosphatidylcholine (LPC) treatment. Monensin, a general inhibitor of recycling pathways, blocked LPC-regulated surface localization of muG2A as well as muG2A-dependent extracellular signal-regulated kinase (ERK) activation and cell migration induced by LPC treatment. Mutation of the conserved DRY motif (R-->A) enhanced the surface expression of muG2A, resulting in its resistance to monensin inhibition of ERK activation. Our data suggest that intracellular sequestration and surface expression regulated by LPC, rather than direct agonistic activity control the signaling responses of murine G2A toward LPC.
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Affiliation(s)
- Li Wang
- Department of Microbiology, Immunology, and Molecular Genetics, UCLA, Los Angeles, CA 90095, USA
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30
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Kristiansen K. Molecular mechanisms of ligand binding, signaling, and regulation within the superfamily of G-protein-coupled receptors: molecular modeling and mutagenesis approaches to receptor structure and function. Pharmacol Ther 2004; 103:21-80. [PMID: 15251227 DOI: 10.1016/j.pharmthera.2004.05.002] [Citation(s) in RCA: 394] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The superfamily of G-protein-coupled receptors (GPCRs) could be subclassified into 7 families (A, B, large N-terminal family B-7 transmembrane helix, C, Frizzled/Smoothened, taste 2, and vomeronasal 1 receptors) among mammalian species. Cloning and functional studies of GPCRs have revealed that the superfamily of GPCRs comprises receptors for chemically diverse native ligands including (1) endogenous compounds like amines, peptides, and Wnt proteins (i.e., secreted proteins activating Frizzled receptors); (2) endogenous cell surface adhesion molecules; and (3) photons and exogenous compounds like odorants. The combined use of site-directed mutagenesis and molecular modeling approaches have provided detailed insight into molecular mechanisms of ligand binding, receptor folding, receptor activation, G-protein coupling, and regulation of GPCRs. The vast majority of family A, B, C, vomeronasal 1, and taste 2 receptors are able to transduce signals into cells through G-protein coupling. However, G-protein-independent signaling mechanisms have also been reported for many GPCRs. Specific interaction motifs in the intracellular parts of these receptors allow them to interact with scaffold proteins. Protein engineering techniques have provided information on molecular mechanisms of GPCR-accessory protein, GPCR-GPCR, and GPCR-scaffold protein interactions. Site-directed mutagenesis and molecular dynamics simulations have revealed that the inactive state conformations are stabilized by specific interhelical and intrahelical salt bridge interactions and hydrophobic-type interactions. Constitutively activating mutations or agonist binding disrupts such constraining interactions leading to receptor conformations that associates with and activate G-proteins.
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Affiliation(s)
- Kurt Kristiansen
- Department of Pharmacology, Institute of Medical Biology, University of Tromsø, N-9037 Tromsø, Norway.
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31
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Bryson-Richardson RJ, Logan DW, Currie PD, Jackson IJ. Large-scale analysis of gene structure in rhodopsin-like GPCRs: evidence for widespread loss of an ancient intron. Gene 2004; 338:15-23. [PMID: 15302402 DOI: 10.1016/j.gene.2004.05.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2003] [Revised: 04/05/2004] [Accepted: 05/06/2004] [Indexed: 10/26/2022]
Abstract
The G-protein-coupled receptors (GPCRs) are a large superfamily of seven transmembrane domain-spanning proteins that mediate signal transduction by activation of G-proteins. Mammalian GPCR genes are reputed to be largely intron-deficient, but there have been no reports of using genome-wide analyses of gene structure to investigate this. Using complete genome sequences, we analysed the intron content of over 850 members of the rhodopsin-like GPCR subfamily (family A G-protein-coupled receptor or GPCR-A) in four species. We find that mouse and human GPCR-As have a large and significant reduction in intron number compared to the rest of their genome. In contrast, invertebrate GPCR-As have an intron repertoire similar to, or slightly greater than, the rest of their genome, suggesting that the reduced intron content in mammals is due to widespread intron loss. Furthermore, we provide a specific example of intron loss through analysis of an intron that is conserved in position and phase within a phylogenetically diverse range of GPCR-As within six vertebrate and invertebrate species. Together, these two lines of evidence provide compelling evidence for the widespread loss of introns during the evolution of the mammalian GPCR-A family.
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32
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Ally RA, Ives KL, Traube E, Eltounsi I, Chen PW, Cahill PJ, Battey JF, Hellmich MR, Kroog GS. Agonist- and protein kinase C-induced phosphorylation have similar functional consequences for gastrin-releasing peptide receptor signaling via Gq. Mol Pharmacol 2003; 64:890-904. [PMID: 14500746 DOI: 10.1124/mol.64.4.890] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Acute desensitization of many guanine nucleotide-binding protein-coupled receptors (GPCRs) requires receptor phosphorylation and subsequent binding of an arrestin. GPCRs are substrates for phosphorylation by several classes of kinases. Gastrin-releasing peptide receptor (GRPr) is phosphorylated by a kinase other than protein kinase C (PKC) after exposure to agonist and is also a substrate for PKC-dependent phosphorylation after treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA). Using GRPr mutants, we examined receptor domains required for agonist- and TPA-induced phosphorylation of GRPr and consequences of these phosphorylation events on GRPr signaling via Gq. Agonist- and TPA-stimulated GRPr phosphorylation in cells require an intact carboxyl terminal domain (CTD). GRPr is phosphorylated in vitro by GPCR kinase 2 (GRK2) and multiple PKC isoforms. An intact DRY motif is required for agonist-stimulated phosphorylation in cells, and agonist-dependent GRK2 phosphorylation in vitro. Although GRPr CTD mutants do not show enhanced in vitro coupling to Gq relative to intact GRPr, CTD mutants have more potent Gq-dependent signaling in cells. Acute desensitization involves CTD-independent processes because desensitization can precede ligand binding in intact GRPr and CTD mutants. TPA-mediated impairment of GRPr-Gq signaling in cells also requires an intact CTD. Similar to GRK2 phosphorylation, PKC phosphorylation reduces GRPr-Gq coupling by approximately 80% in vitro. Arrestin translocation to plasma membrane requires agonist, an intact DRY motif, and GRPr phosphorylation. Therefore, agonist- and PKC-induced GRPr phosphorylation sites are in nearby regions of the receptor, and phosphorylation at both sites has similar functional consequences for Gq signaling.
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Affiliation(s)
- Roxanne A Ally
- Department of Molecular Pharmacology, Chanin 302D, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461, USA
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33
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Oliveira L, Paiva PB, Paiva ACM, Vriend G. Sequence analysis reveals how G protein-coupled receptors transduce the signal to the G protein. Proteins 2003; 52:553-60. [PMID: 12910455 DOI: 10.1002/prot.10489] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Sequence entropy-variability plots based on alignments of very large numbers of sequences-can indicate the location in proteins of the main active site and modulator sites. In the previous article in this issue, we applied this observation to a series of well-studied proteins and concluded that it was possible to detect most of the residues with a known functional role. Here, we apply the method to rhodopsin-like G protein-coupled receptors. Our conclusion is that G protein binding is the main evolutionary constraint on these receptors, and that other ligands, such as agonists, act as modulators. The activation of the receptors can be described as a simple, two-step process, and the residues involved in signal transduction can be identified.
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Affiliation(s)
- Laerte Oliveira
- Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
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34
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Gáborik Z, Jagadeesh G, Zhang M, Spät A, Catt KJ, Hunyady L. The role of a conserved region of the second intracellular loop in AT1 angiotensin receptor activation and signaling. Endocrinology 2003; 144:2220-8. [PMID: 12746278 DOI: 10.1210/en.2002-0135] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The pleiotropic actions of angiotensin II are mediated by the primarily G(q) protein-coupled type 1 angiotensin (AT(1)) receptor. In this study a mutational analysis of the function of the conserved DRYXXV/IXXPL domain in the second intracellular loop of the rat AT(1A) receptor was performed in COS7 cells. Alanine substitution studies showed that single replacement of the highly conserved Asp(125) and Arg(126), but not Tyr(127), moderately impaired angiotensin II-induced inositol phosphate signaling. However, concomitant substitution of both Asp(125) and Arg(126) caused marked reduction of both inositol phosphate signaling and receptor internalization. Alanine scanning of the adjacent residues showed that substitution of Ile(130), His(132), and Pro(133) reduced agonist-induced inositol phosphate signal generation, whereas mutations of Met(134) also impaired receptor internalization. Expression of the D125A mutant AT(1A) receptor in COS7 cells endowed the receptor with moderate constitutive activity, as indicated by its enhanced basal Elk1 promoter activity and inositol phosphate response to partial agonists. Angiotensin II-induced stimulation of the Elk1 promoter showed parallel impairment with inositol phosphate signal generation in receptors containing mutations in this region of the AT(1A) receptor. These data confirm that Ca(2+) signal generation is required for the nuclear effects of angiotensin II-induced ERK activation. They are also consistent with the role of the conserved DRY sequence of the AT(1A) receptor in receptor activation, and of Asp(125) in constraining the receptor in its inactive conformation. Furthermore, in the cytoplasmic helical extension of the third helix, an apolar surface that includes Ile(130) and Met(134) appears to have a direct role in G protein coupling.
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Affiliation(s)
- Zsuzsanna Gáborik
- Department of Physiology, Semmelweis University, Faculty of Medicine, H-1088 Budapest, Hungary
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35
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Taylor WR, Munro REJ, Petersen K, Bywater RP. Ab initio modelling of the N-terminal domain of the secretin receptors. Comput Biol Chem 2003; 27:103-14. [PMID: 12821307 DOI: 10.1016/s1476-9271(03)00020-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
G protein coupled receptors of the secretin family are activated by peptide hormones of about 30 residues in length. There is considerable sequence homology within both the hormone and receptor families. The receptors possess in addition to the integral membrane domain a characteristic extracellular domain of about 120 residues in length, having conserved cysteine residues, which are involved in disulphide bridge formation, and tryptophanes, which have been shown to be critical for hormone binding. This extracellular domain does not have detectable homology to any known protein fold. In order to be able to propose a structure for this domain we have used ab initio prediction methods combined with constraints based on experimental results for the disulphide connectivity. The results of computational tools for predicting secondary structure and accessibility, together with ligand binding and mutational data and other structural considerations were used in the ab initio protein folding programs DRAGON and GADGET and also the simpler program RAMBLE, which was able to explore different permutations of disulphide bond connectivity, tryptophan side chain orientation and chain topology. The methods generated a limited number of plausible models but no single unique solution was found under the constraints. One of these was refined into a full atomic model that contained a possible peptide binding site comprising the most conserved residues.
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Affiliation(s)
- William R Taylor
- Division of Mathematical Biology, National Institute for Medical Research, The Ridgeway, Mill Hill, NW7 1AA, London, UK
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36
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Brasili L, Sorbi C, Franchini S, Manicardi M, Angeli P, Marucci G, Leonardi A, Poggesi E. 1,3-dioxolane-based ligands as a novel class of alpha1-adrenoceptor antagonists. J Med Chem 2003; 46:1504-11. [PMID: 12672251 DOI: 10.1021/jm021078o] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
1,3-Dioxolane-based compounds (2-14) were synthesized, and the pharmacological profiles at alpha(1)-adrenoceptor subtypes were assessed by functional experiments in isolated rat vas deferens (alpha(1A)), spleen (alpha(1B)), and aorta (alpha(1D)). Compound 9, with a pA(2) of 7.53, 7.36, and 8.65 at alpha(1A), alpha(1B), and alpha(1D), respectively, is the most potent antagonist of the series, while compound 10 with a pA(2) of 8.37 at alpha(1D) subtype and selectivity ratios of 162 (alpha(1D)/alpha(1A)) and 324 (alpha(1D)/alpha(1B)) is the most selective. Binding assays in CHO cell membranes expressing human cloned alpha(1)-adrenoceptor subtypes confirm the pharmacological profiles derived from functional experiments, although the selectivity values are somewhat lower. Therefore, it is concluded that 1,3-dioxolane-based ligands are a new class of alpha(1)-adrenoceptor antagonists.
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Affiliation(s)
- Livio Brasili
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Modena e Reggio Emilia, Via Campi 183, Italy.
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37
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Feng W, Song ZH. Effects of D3.49A, R3.50A, and A6.34E mutations on ligand binding and activation of the cannabinoid-2 (CB2) receptor. Biochem Pharmacol 2003; 65:1077-85. [PMID: 12663043 DOI: 10.1016/s0006-2952(03)00005-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
In several G protein-coupled receptors (GPCRs), the Asp-Arg-Tyr (DRY) motif at the bottom of third transmembrane domain and the amino acid at position 6.34 in the sixth transmembrane domain have been shown to play important roles in signal transduction. In this study, we propose that in the cannabinoid-2 (CB2) receptor, R3.50 in the DRY motif may be crucial for interacting with G proteins, and D3.49 and A6.34 may be important for constraining the receptor in an inactive conformation. To test our hypothesis, R3.50A, D3.49A, and A6.34E mutations of the human CB2 receptor were made by site-directed mutagenesis. These mutant receptors were stably transfected into human embryonic 293 cells, and their ligand binding and signal transduction properties were analyzed. Similar to other GPCRs, R3.50 of the CB2 receptor is crucial for signal transduction. Unlike other GPCRs, D3.49 and A6.34 of the CB2 receptor do not seem to be important for keeping the receptor in an inactive state. Furthermore, D3.49A and A6.34E mutations abolished ligand binding, and all three mutations abolished constitutive activity of the wild-type CB2 receptor.
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Affiliation(s)
- Wenke Feng
- Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY 40292, USA
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38
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Ni A, Yin H, Agata J, Yang Z, Chao L, Chao J. Overexpression of kinin B1 receptors induces hypertensive response to des-Arg9-bradykinin and susceptibility to inflammation. J Biol Chem 2003; 278:219-25. [PMID: 12411434 DOI: 10.1074/jbc.m209490200] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We demonstrated that rat kinin B(1) receptors displayed a ligand-independent constitutive activity, assessed through inositol phosphate production in transiently or stably transfected human embryonic kidney 293A cells. Substitution of Ala for Asn(130) in the third transmembrane domain resulted in additional constitutive activation of the B(1) receptor. The constitutively active mutant N130A receptor could be further activated by the B(1) receptor agonist des-Arg(9)-bradykinin. To gain insights into the physiological function of the B(1) receptor, we have generated transgenic mice overexpressing wild-type and constitutively active mutant receptors under the control of human cytomegalovirus immediately early gene enhancer/promoter. The rat B(1) receptor transgene expression was detected in the aorta, brain, heart, lung, liver, kidney, uterus, and prostate of transgenic mice by reverse transcription-polymerase chain reaction/Southern blot analysis. Transgenic mice were fertile and normotensive. Overexpression of B(1) receptors exacerbated paw edema induced by carrageenan and rendered transgenic mice more susceptible to lipopolysaccharide-induced endotoxic shock. Interestingly, the hemodynamic response to kinins was altered in transgenic mice, with des-Arg(9)-bradykinin inducing blood pressure increase when intravenously administered. Our study supports an important role for B(1) receptors in modulating inflammatory responses and for the first time demonstrates that B(1) receptors mediate a hypertensive response to des-Arg(9)-bradykinin.
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Affiliation(s)
- Aiguo Ni
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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39
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Madsen O, Willemsen D, Ursing BM, Arnason U, de Jong WW. Molecular evolution of the mammalian alpha 2B adrenergic receptor. Mol Biol Evol 2002; 19:2150-60. [PMID: 12446807 DOI: 10.1093/oxfordjournals.molbev.a004040] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The alpha 2B adrenergic receptor (A2AB) is a heptahelical G protein-coupled receptor for catecholamines. We compared the almost complete coding region (about 1,175 bp) of the A2AB gene from 48 mammalian species, including eight newly determined sequences, representing all the 18 eutherian and two marsupial orders. Comparison of the encoded proteins reveals that residues thought to be involved in agonist binding are highly conserved, as are the regions playing a role in G protein-coupling. The three extracellular loops are generally more variable than the transmembrane domains and two of the intracellular loops, indicating a lower functional constraint. However, the greatest variation is observed in the very long, third intracellular loop, where only a few residues and a polyglutamyl tract are preserved. Although this polyglutamyl domain displays a great variation in length, its presence in all described A2ABs confirms its proposed role in agonist-dependent phosphorylation of the third intracellular loop. Phylogenetic analyses of the A2AB data set, including Bayesian methods, recognized the superordinal clades Afrotheria, Laurasiatheria, and Euarchontoglires, in agreement with recent molecular evidence, albeit with lower support. Within Afrotheria, A2AB strongly supports the paenungulate clade and the association of the continental African otter shrew with Malagasy tenrecs. Among Laurasiatheria, A2AB confirms the nesting of whales within the artiodactyls, as a sister group to hippopotamus. Within the Euarchontoglires, there is constant support for rodent monophyly.
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Affiliation(s)
- Ole Madsen
- Department of Biochemistry 161, University of Nijmegen, 6500 HB Nijmegen, The Netherlands
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40
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Henneke G, Gueguen Y, Flament D, Azam P, Querellou J, Dietrich J, Hübscher U, Raffin JP. Replication factor C from the hyperthermophilic archaeon Pyrococcus abyssi does not need ATP hydrolysis for clamp-loading and contains a functionally conserved RFC PCNA-binding domain. J Mol Biol 2002; 323:795-810. [PMID: 12417194 DOI: 10.1016/s0022-2836(02)01028-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The molecular organization of the replication complex in archaea is similar to that in eukaryotes. Only two proteins homologous to subunits of eukaryotic replication factor C (RFC) have been detected in Pyrococcus abyssi (Pab). The genes encoding these two proteins are arranged in tandem. We cloned these two genes and co-expressed the corresponding recombinant proteins in Escherichia coli. Two inteins present in the gene encoding the small subunit (PabRFC-small) were removed during cloning. The recombinant protein complex was purified by anion-exchange and hydroxyapatite chromatography. Also, the PabRFC-small subunit could be purified, while the large subunit (PabRFC-large) alone was completely insoluble. The highly purified PabRFC complex possessed an ATPase activity, which was not enhanced by DNA. The Pab proliferating cell nuclear antigen (PCNA) activated the PabRFC complex in a DNA-dependent manner, but the PabRFC-small ATPase activity was neither DNA-dependent nor PCNA-dependent. The PabRFC complex was able to stimulate PabPCNA-dependent DNA synthesis by the Pabfamily D heterodimeric DNA polymerase. Finally, (i) the PabRFC-large fraction cross-reacted with anti-human-RFC PCNA-binding domain antibody, corroborating the conservation of the protein sequence, (ii) the human PCNA stimulated the PabRFC complex ATPase activity in a DNA-dependent way and (iii) the PabRFC complex could load human PCNA onto primed single-stranded circular DNA, suggesting that the PCNA-binding domain of RFC has been functionally conserved during evolution. In addition, ATP hydrolysis was not required either for DNA polymerase stimulation or PCNA-loading in vitro.
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Affiliation(s)
- Ghislaine Henneke
- Ifremer, Laboratoire de Microbiologie et Biotechnologie des Extrêmophiles, DRV/VP, BP 70, F-29280 Plouzané, France
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41
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Salinas RK, Shida CS, Pertinhez TA, Spisni A, Nakaie CR, Paiva ACM, Schreier S. Trifluoroethanol and binding to model membranes stabilize a predicted turn in a peptide corresponding to the first extracellular loop of the angiotensin II AT(1A) receptor. Biopolymers 2002; 65:21-31. [PMID: 12209469 DOI: 10.1002/bip.10209] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Homology modeling of the angiotensin II AT(1A) receptor based on rhodopsin's crystal structure has assigned the 92-100 (YRWPFGNHL) sequence of the receptor to its first extracellular loop. Solution and membrane-bound conformational properties of a peptide containing this sequence (EL1) were examined by CD, fluorescence, and (1)H-NMR. CD spectra in aqueous solution revealed an equilibrium between less organized and folded conformers. NMR spectra indicated the coexistence of trans and cis isomers of the Trp(3)-Pro(4) bond. A positive band at 226 nm in the CD spectra suggested aromatic ring stacking, modulated by EL1's ionization degree. CD spectra showed that trifluoroethanol (TFE), or binding to detergent micelles and phospholipid bilayers, shifted the equilibrium toward conformers with higher secondary structure content. Different media gave rise to spectra suggestive of different beta-turns. Chemical shift changes in the NMR spectra corroborated the stabilization of different conformations. Thus, environments of lower polarity or binding to interfaces probably favored the formation of hydrogen bonds, stabilizing beta-turns, predicted for this sequence in the whole receptor. Increases in Trp(3) fluorescence intensity and anisotropy, blue shifts of the maximum emission wavelength, and pK changes also evinced the interaction between EL1 and model membranes. Binding was seen to depend on both hydrophobic and electrostatic interactions, as well as lipid phase packing. Studies with water-soluble and membrane-bound fluorescence quenchers demonstrated that Trp(3) is located close to the water-membrane interface. The results are discussed with regard to possible implications in receptor folding and function.
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Affiliation(s)
- Roberto K Salinas
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, CP 26077, 05513-970, São Paulo, Brazil
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42
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Betti L, Botta M, Corelli F, Floridi M, Giannaccini G, Maccari L, Manetti F, Strappaghetti G, Tafi A, Corsano S. Alpha(1)-adrenoceptor antagonists. 4. Pharmacophore-based design, synthesis, and biological evaluation of new imidazo-, benzimidazo-, and indoloarylpiperazine derivatives. J Med Chem 2002; 45:3603-11. [PMID: 12166933 DOI: 10.1021/jm011077g] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
As a part of a program aimed at discovering compounds endowed with alpha(1)-adrenoceptor (AR) blocking properties, in this paper we describe the synthesis and biological characterization of the compounds designed to fully match a three-dimensional pharmacophore model for alpha(1)-AR antagonists previously developed by our research group. Accordingly, the structure of trazodone (1), identified during a database search performed by using the model as a 3D query, was chosen as the starting point for this study and modified following suggestions derived from a literature survey. In particular, the triazolopyridine moiety of trazodone was replaced with different heteroaromatic rings (such as imidazole, benzimidazole, and indole), and a pyridazin-3(2H)-one moiety was inserted into the scaffold of the new compounds to increase the overall length of the molecules and to allow for a complete fit into all the pharmacophore features. Our aim was also to study the influence of the position of both the chloro and the methoxy groups on the piperazine phenyl ring, as well as the effect of the lengthening or shortening of the polymethylene spacer linking the phenylpiperazine moiety to the terminal heterocyclic portion. Compounds obtained by such structural optimization share a 6-(imidazol-1-yl)-, 6-(benzimidazol-1-yl)-, or 6-(indol-1-yl)pyridazin-3(2H)-one as a common structural feature that represents an element of novelty in the SAR of arylpiperazine compounds acting toward alpha(1)-AR. Biological evaluation by radioligand receptor binding assays toward alpha(1)-AR, alpha(2)-AR, and 5-HT(1A) serotoninergic receptors indicated compounds characterized by very good alpha(1)-AR affinity and selectivity. Very interestingly, chemical features (such as the o-methoxyphenylpiperazinyl moiety and an alkyl spacer of three or four methylene units) that generally do not allow for 5-HT(1A)/alpha(1) selectivity led to compounds 2c and 6c with a 5-HT(1A)/alpha(1) ratio of 286 and 281, respectively. Finally, compounds with the best alpha(1)-AR affinity profile (2c, 5f, and 6c) were demonstrated to be alpha(1)-AR antagonists.
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Affiliation(s)
- Laura Betti
- Dipartimento di Psichiatria, Neurobiologia, Farmacologia e Biotecnologie, Università di Pisa, Italy
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43
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López-Rodríguez ML, Vicente B, Deupi X, Barrondo S, Olivella M, Morcillo MJ, Behamú B, Ballesteros JA, Sallés J, Pardo L. Design, synthesis and pharmacological evaluation of 5-hydroxytryptamine(1a) receptor ligands to explore the three-dimensional structure of the receptor. Mol Pharmacol 2002; 62:15-21. [PMID: 12065750 DOI: 10.1124/mol.62.1.15] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In this work, we evaluate the structural differences of transmembrane helix 3 in rhodopsin and the 5-hydroxytryptamine 1A (5-HT1A) receptor caused by their different amino acid sequence. Molecular dynamics simulations of helix 3 in the 5-HT1A receptor tends to bend toward helix 5, in sharp contrast to helix 3 in rhodopsin, which is properly located within the position observed in the crystal structure. The relocation of the central helix 3 in the helical bundle facilitates the experimentally derived interactions between the neurotransmitters and the Asp residue in helix 3 and the Ser/Thr residues in helix 5. The different amino acid sequence that forms helix 3 in rhodopsin (basically the conserved Gly(3.36)Glu(3.37) motif in the opsin family) and the 5-HT1A receptor (the conserved Cys(3.36)Thr(3.37) motif in the neurotransmitter family) produces these structural divergences. These structural differences were experimentally checked by designing and testing ligands that contain comparable functional groups but at different interatomic distance. We have estimated the position of helix 3 relative to the other helices by systematically changing the distance between the functional groups of the ligands (1 and 2) that interact with the residues in the receptor. Thus, ligand 1 optimally interacts with a model of the 5-HT1A receptor that matches rhodopsin template, whereas ligand 2 optimally interacts with a model that possesses the proposed conformation of helix 3. The lack of affinity of 1 (K(i) > 10,000 nM) and the high affinity of 2 (K(i) = 24 nM) for the 5-HT1A receptor binding sites, provide experimental support to the proposed structural divergences of helix 3 between the 5-HT1A receptor and rhodopsin.
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Affiliation(s)
- María L López-Rodríguez
- Departamento de Química Orgánica I, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain
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44
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Bockaert J, Claeysen S, Bécamel C, Pinloche S, Dumuis A. G protein-coupled receptors: dominant players in cell-cell communication. INTERNATIONAL REVIEW OF CYTOLOGY 2002; 212:63-132. [PMID: 11804040 DOI: 10.1016/s0074-7696(01)12004-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The G protein-coupled receptors (GPCRs) are the most numerous and the most diverse type of receptors (1-5% of the complete invertebrate and vertebrate genomes). They transduce messages as different as odorants, nucleotides, nucleosides, peptides, lipids, and proteins. There are at least eight families of GPCRs that show no sequence similarities and that use different domains to bind ligands and activate a similar set of G proteins. Homo- and heterodimerization of GPCRs seem to be the rule, and in some cases an absolute requirement, for activation. There are about 100 orphan GPCRs in the human genome which will be used to find new message molecules. Mutations of GPCRs are responsible for a wide range of genetic diseases. The importance of GPCRs in physiological processes is illustrated by the fact that they are the target of the majority of therapeutical drugs and drugs of abuse.
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45
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Dias JA, Cohen BD, Lindau-Shepard B, Nechamen CA, Peterson AJ, Schmidt A. Molecular, structural, and cellular biology of follitropin and follitropin receptor. VITAMINS AND HORMONES 2002; 64:249-322. [PMID: 11898394 DOI: 10.1016/s0083-6729(02)64008-7] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Follitropin and the follitropin receptor are essential for normal gamete development in males and females. This review discusses the molecular genetics and structural and cellular biology of the follitropin/follitropin receptor system. Emphasis is placed on the human molecules when possible. The structure and regulation of the genes for the follitropin beta subunit and the follitropin receptor is discussed. Control of systemic and cellular protein levels is explained. The structural biology of each protein is described, including protein structure, motifs, and activity relationships. Finally, the follitropin/follitropin receptor signal transduction system is discussed.
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Affiliation(s)
- James A Dias
- Wadsworth Center, David Axelrod Institute for Public Health, New York State Department of Health, Albany, New York 12208, USA
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46
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Quaglia W, Pigini M, Piergentili A, Giannella M, Gentili F, Marucci G, Carrieri A, Carotti A, Poggesi E, Leonardi A, Melchiorre C. Structure-activity relationships in 1,4-benzodioxan-related compounds. 7. Selectivity of 4-phenylchroman analogues for alpha(1)-adrenoreceptor subtypes. J Med Chem 2002; 45:1633-43. [PMID: 11931617 DOI: 10.1021/jm011066n] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
WB4101 (1)-related compounds 5-10 were synthesized, and their biological profile at alpha(1)-adrenoreceptor (AR) subtypes and 5-HT(1A) serotoninergic receptors was assessed by binding assays in Chinese hamster ovary and HeLa cell membranes expressing the human cloned receptors. Moreover, their receptor selectivity was further determined in functional experiments in isolated rat prostate (alpha(1A)), vas deferens (alpha(1A)), aorta (alpha(1D)), and spleen (alpha(1B)). In functional assays, compound 5 was the most potent at alpha(1D)-ARs with a reversed selectivity profile (alpha(1D) > alpha(1A) > alpha(1B)) relative to both prototype 1 and phendioxan (2) (alpha(1A) > alpha(1D) > alpha(1B)), whereas compound 8, bearing a carbonyl moiety at position 1, was the most potent at alpha(1A)-ARs with a selectivity profile similar to that of prototypes. The least potent of the series was the trans isomer 6, suggesting that optimum alpha(1)-AR blocking activity in this series is associated with a cis relationship between the 2-side chain and the 4-phenyl ring rather than a trans relationship as previously observed for the 2-side chain and the 3-phenyl ring in 2 and related compounds. Binding affinity results were not in complete agreement with the selectivity profiles deriving from functional experiments. Although a firm explanation was not available, neutral and negative antagonism and receptor dimerization were considered as two possibilities to account for the difference between binding and functional affinities. Finally, compound 5 was selected for a modeling study in comparison with 1, mephendioxan (3), and open phendioxan (4) to achieve information on the physicochemical interactions that account for its high affinity toward alpha(1d/D)-ARs.
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MESH Headings
- Adrenergic alpha-Antagonists/chemical synthesis
- Adrenergic alpha-Antagonists/chemistry
- Adrenergic alpha-Antagonists/pharmacology
- Animals
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/physiology
- CHO Cells
- Chromans/chemical synthesis
- Chromans/chemistry
- Chromans/pharmacology
- Cricetinae
- Dioxanes/chemical synthesis
- Dioxanes/chemistry
- Dioxanes/pharmacology
- HeLa Cells
- Humans
- In Vitro Techniques
- Male
- Models, Molecular
- Muscle Contraction/drug effects
- Muscle, Smooth/drug effects
- Muscle, Smooth/physiology
- Prostate/drug effects
- Prostate/physiology
- Radioligand Assay
- Rats
- Rats, Wistar
- Receptors, Adrenergic, alpha-1/drug effects
- Receptors, Adrenergic, alpha-1/metabolism
- Receptors, Serotonin/metabolism
- Receptors, Serotonin, 5-HT1
- Spleen/drug effects
- Spleen/physiology
- Structure-Activity Relationship
- Vas Deferens/drug effects
- Vas Deferens/physiology
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Affiliation(s)
- Wilma Quaglia
- Department of Chemical Sciences, University of Camerino, Via S. Agostino 1, 62032 Camerino (MC), Italy
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47
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Parrish W, Eilers M, Ying W, Konopka JB. The cytoplasmic end of transmembrane domain 3 regulates the activity of the Saccharomyces cerevisiae G-protein-coupled alpha-factor receptor. Genetics 2002; 160:429-43. [PMID: 11861550 PMCID: PMC1461982 DOI: 10.1093/genetics/160.2.429] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The binding of alpha-factor to its receptor (Ste2p) activates a G-protein-signaling pathway leading to conjugation of MATa cells of the budding yeast S. cerevisiae. We conducted a genetic screen to identify constitutively activating mutations in the N-terminal region of the alpha-factor receptor that includes transmembrane domains 1-5. This approach identified 12 unique constitutively activating mutations, the strongest of which affected polar residues at the cytoplasmic ends of transmembrane domains 2 and 3 (Asn84 and Gln149, respectively) that are conserved in the alpha-factor receptors of divergent yeast species. Targeted mutagenesis, in combination with molecular modeling studies, suggested that Gln149 is oriented toward the core of the transmembrane helix bundle where it may be involved in mediating an interaction with Asn84. These residues appear to play specific roles in maintaining the inactive conformation of the protein since a variety of mutations at either position cause constitutive receptor signaling. Interestingly, the activity of many mammalian G-protein-coupled receptors is also regulated by conserved polar residues (the E/DRY motif) at the cytoplasmic end of transmembrane domain 3. Altogether, the results of this study suggest a conserved role for the cytoplasmic end of transmembrane domain 3 in regulating the activity of divergent G-protein-coupled receptors.
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Affiliation(s)
- William Parrish
- Department of Molecular Genetics and Microbiology, Center for Structural Biology, State University of New York, Stony Brook, New York 11794-5222, USA
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48
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Nelson CS, Ikeda M, Gompf HS, Robinson ML, Fuchs NK, Yoshioka T, Neve KA, Allen CN. Regulation of melatonin 1a receptor signaling and trafficking by asparagine-124. Mol Endocrinol 2001; 15:1306-17. [PMID: 11463855 DOI: 10.1210/mend.15.8.0681] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Melatonin is a pineal hormone that regulates seasonal reproduction and has been used to treat circadian rhythm disorders. The melatonin 1a receptor is a seven- transmembrane domain receptor that signals predominately via pertussis toxin-sensitive G-proteins. Point mutations were created at residue N124 in cytoplasmic domain II of the receptor and the mutant receptors were expressed in a neurohormonal cell line. The acidic N124D- and E-substituted receptors had high-affinity (125)I-melatonin binding and a subcellular localization similar to the neutral N124N wild-type receptor. Melatonin efficacy for the inhibition of cAMP by N124D and E mutations was significantly decreased. N124D and E mutations strongly compromised melatonin efficacy and potency for inhibition of K(+)-induced intracellular Ca(++) fluxes and eliminated control of spontaneous calcium fluxes. However, these substitutions did not appear to affect activation of Kir3 potassium channels. The hydrophobic N124L and N124A or basic N124K mutations failed to bind (125)I-melatonin and appeared to aggregate or traffic improperly. N124A and N124K receptors were retained in the Golgi. Therefore, mutants at N124 separated into two sets: the first bound (125)I-melatonin with high affinity and trafficked normally, but with reduced inhibitory coupling to adenylyl cyclase and Ca(++) channels. The second set lacked melatonin binding and exhibited severe trafficking defects. In summary, asparagine-124 controls melatonin receptor function as evidenced by changes in melatonin binding, control of cAMP levels, and regulation of ion channel activity. Asparagine-124 also has a unique structural effect controlling receptor distribution within the cell.
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MESH Headings
- Adenylyl Cyclases/metabolism
- Animals
- Asparagine
- Calcium/metabolism
- Calcium Channels/metabolism
- Cyclic AMP/metabolism
- Electrophysiology
- Fluorescent Antibody Technique
- G Protein-Coupled Inwardly-Rectifying Potassium Channels
- Golgi Apparatus/metabolism
- Iodine Radioisotopes
- Melatonin/metabolism
- Melatonin/pharmacology
- Mice
- Mutagenesis, Site-Directed
- Pituitary Neoplasms
- Potassium/pharmacology
- Potassium Channels/drug effects
- Potassium Channels/physiology
- Potassium Channels, Inwardly Rectifying
- Receptors, Cell Surface/chemistry
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/physiology
- Receptors, Cytoplasmic and Nuclear/chemistry
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/physiology
- Receptors, Melatonin
- Reverse Transcriptase Polymerase Chain Reaction
- Signal Transduction
- Tumor Cells, Cultured
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Affiliation(s)
- C S Nelson
- Center for Research on Occupational and Environmental Toxicology, Oregon Health Sciences University, Portland, Oregon 97201, USA
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49
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Lukashova V, Asselin C, Krolewski JJ, Rola-Pleszczynski M, Stanková J. G-protein-independent activation of Tyk2 by the platelet-activating factor receptor. J Biol Chem 2001; 276:24113-21. [PMID: 11309383 DOI: 10.1074/jbc.m100720200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Platelet-activating factor (PAF) is a potent pro-inflammatory phospholipid with multiple physiological and pathological effects. PAF exerts its activity through a specific heptohelical G-protein coupled receptor, expressed on a variety of cell types, including leukocytes. In this study, we showed that PAF induced a rapid tyrosine phosphorylation of the Tyk2 kinase in the monocytic cell lines U937 and MonoMac-1. PAF-initiated Tyk2 phosphorylation was also observed in COS-7 cells transiently transfected with the human PAF receptor (PAFR) and Tyk2 cDNAs. In addition, we found that Tyk2 co-immunoprecipitated and co-localized with PAFR, independently of ligand binding. Deletion mutants of Tyk2 indicated that the N terminus of the kinase was important for the binding to PAFR. Activation of Tyk2 was followed by a time-dependent 2-4-fold increase in the level of tyrosine phosphorylation of signal transducers and activators of transcription 1 (STAT1), STAT2, and STAT3 and a sustained 2.5-fold increase in STAT5 tyrosine phosphorylation. In MonoMac-1 cells, STAT1 and STAT3 translocated to the nucleus following PAF stimulation, and their translocation in transiently transfected COS-7 cells was shown to be dependent on the presence of Tyk2. In addition, when COS-7 cells were transfected with PAFR and constructs containing PAFR promoter 1, coupled to the luciferase reporter gene, PAF induced a 3.6-fold increase in promoter activation in the presence of Tyk2. Finally, PAFR mutants that could not couple to G-proteins were found to effectively mediate Tyk2 activation and signaling. Taken together, these findings suggest an important role for the Janus kinase/STAT pathway in PAFR signaling, independent of G-proteins, and in the regulation of PAF receptor expression by its ligand.
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Affiliation(s)
- V Lukashova
- Immunology Division, Department of Pediatrics and the Department of Anatomy and Cell Biology, Université de Sherbrooke, Sherbrooke, Québec J1H 5N4, Canada
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50
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Barbaro R, Betti L, Botta M, Corelli F, Giannaccini G, Maccari L, Manetti F, Strappaghetti G, Corsano S. Synthesis, biological evaluation, and pharmacophore generation of new pyridazinone derivatives with affinity toward alpha(1)- and alpha(2)-adrenoceptors. J Med Chem 2001; 44:2118-32. [PMID: 11405649 DOI: 10.1021/jm010821u] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of new pyridazin-3(2H)-one derivatives (3 and 4) were evaluated for their in vitro affinity toward both alpha(1)- and alpha(2)-adrenoceptors by radioligand receptor binding assays. All target compounds showed good affinities for the alpha(1)-adrenoceptor, with K(i) values in the low nanomolar range. The polymethylene chain constituting the spacer between the furoylpiperazinyl pyridazinone and the arylpiperazine moiety was shown to influence the affinity and selectivity of these compounds. Particularly, a gradual increase in affinity was observed by lengthening the polymethylene chain up to a maximum of seven carbon atoms. In addition, compound 3k, characterized by a very interesting alpha(1)-AR affinity (1.9 nM), was also shown to be a highly selective alpha(1)-AR antagonist, the affinity ratio for alpha(2)- and alpha(1)-adrenoceptors being 274. To gain insight into the structural features required for alpha(1) antagonist activity, the pyridazinone derivatives were submitted to a pharmacophore generation procedure using the program Catalyst. The resulting pharmacophore model showed high correlation and predictive power. It also rationalized the relationships between structural properties and biological data of, and external to, the pyridazinone class.
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Affiliation(s)
- R Barbaro
- Istituto di Chimica e Tecnologia del Farmaco, Università di Perugia, Via del Liceo 1, 06123 Perugia, Italy
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