51
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Sekiguchi T, Kuwasako K, Ogasawara M, Takahashi H, Matsubara S, Osugi T, Muramatsu I, Sasayama Y, Suzuki N, Satake H. Evidence for Conservation of the Calcitonin Superfamily and Activity-regulating Mechanisms in the Basal Chordate Branchiostoma floridae: INSIGHTS INTO THE MOLECULAR AND FUNCTIONAL EVOLUTION IN CHORDATES. J Biol Chem 2015; 291:2345-56. [PMID: 26644465 DOI: 10.1074/jbc.m115.664003] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Indexed: 11/06/2022] Open
Abstract
The calcitonin (CT)/CT gene-related peptide (CGRP) family is conserved in vertebrates. The activities of this peptide family are regulated by a combination of two receptors, namely the calcitonin receptor (CTR) and the CTR-like receptor (CLR), and three receptor activity-modifying proteins (RAMPs). Furthermore, RAMPs act as escort proteins by translocating CLR to the cell membrane. Recently, CT/CGRP family peptides have been identified or inferred in several invertebrates. However, the molecular characteristics and relevant functions of the CTR/CLR and RAMPs in invertebrates remain unclear. In this study, we identified three CT/CGRP family peptides (Bf-CTFPs), one CTR/CLR-like receptor (Bf-CTFP-R), and three RAMP-like proteins (Bf-RAMP-LPs) in the basal chordate amphioxus (Branchiostoma floridae). The Bf-CTFPs were shown to possess an N-terminal circular region typical of the CT/CGRP family and a C-terminal Pro-NH2. The Bf-CTFP genes were expressed in the central nervous system and in endocrine cells of the midgut, indicating that Bf-CTFPs serve as brain and/or gut peptides. Cell surface expression of the Bf-CTFP-R was enhanced by co-expression with each Bf-RAMP-LP. Furthermore, Bf-CTFPs activated Bf-CTFP-R·Bf-RAMP-LP complexes, resulting in cAMP accumulation. These results confirmed that Bf-RAMP-LPs, like vertebrate RAMPs, are prerequisites for the function and translocation of the Bf-CTFP-R. The relative potencies of the three peptides at each receptor were similar. Bf-CTFP2 was a potent ligand at all receptors in cAMP assays. Bf-RAMP-LP effects on ligand potency order were distinct to vertebrate CGRP/adrenomedullin/amylin receptors. To the best of our knowledge, this is the first molecular and functional characterization of an authentic invertebrate CT/CGRP family receptor and RAMPs.
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Affiliation(s)
- Toshio Sekiguchi
- From the Noto Marine Laboratory, Division of Marine Environmental Studies, Institute of Nature and Environmental Technology, Kanazawa University, Housu-gun, Ishikawa 927-0553, Japan,
| | - Kenji Kuwasako
- the Frontier Science Research Center, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki, Miyazaki 889-1692, Japan
| | - Michio Ogasawara
- the Department of Nanobiology, Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Hiroki Takahashi
- the Laboratory of Morphogenesis, National Institute for Basic Biology, 38 Nishigonaka Myodaiji, Okazaki 444-8585, Japan
| | - Shin Matsubara
- the Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1, Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan, and
| | - Tomohiro Osugi
- the Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1, Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan, and
| | - Ikunobu Muramatsu
- the Department of Pharmacology, School of Medicine, Kanazawa Medical University, Uchinada, Ishikawa 920-0293, Japan
| | - Yuichi Sasayama
- From the Noto Marine Laboratory, Division of Marine Environmental Studies, Institute of Nature and Environmental Technology, Kanazawa University, Housu-gun, Ishikawa 927-0553, Japan
| | - Nobuo Suzuki
- From the Noto Marine Laboratory, Division of Marine Environmental Studies, Institute of Nature and Environmental Technology, Kanazawa University, Housu-gun, Ishikawa 927-0553, Japan
| | - Honoo Satake
- the Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1, Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan, and
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Abstract
It is now recognized that G protein-coupled receptors (GPCRs), once considered largely independent functional units, have a far more diverse molecular architecture. Receptor activity-modifying proteins (RAMPs) provide an important example of proteins that interact with GPCRs to modify their function. RAMPs are able to act as pharmacological switches and chaperones, and they can regulate signaling and/or trafficking in a receptor-dependent manner. This review covers recent discoveries in the RAMP field and summarizes the known GPCR partners and functions of RAMPs. We also discuss the first peptide-bound structures of RAMP-GPCR complexes, which give insight into the molecular mechanisms that enable RAMPs to alter the pharmacology and signaling of GPCRs.
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Affiliation(s)
- Debbie L Hay
- School of Biological Sciences and Maurice Wilkins Center, University of Auckland, Auckland 1142, New Zealand;
| | - Augen A Pioszak
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104;
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Russo AF. CGRP as a neuropeptide in migraine: lessons from mice. Br J Clin Pharmacol 2015; 80:403-14. [PMID: 26032833 DOI: 10.1111/bcp.12686] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 04/25/2015] [Accepted: 05/18/2015] [Indexed: 01/04/2023] Open
Abstract
Migraine is a neurological disorder that is far more than just a bad headache. A hallmark of migraine is altered sensory perception. A likely contributor to this altered perception is the neuropeptide calcitonin gene-related peptide (CGRP). Over the past decade, CGRP has become firmly established as a key player in migraine. Although the mechanisms and sites of action by which CGRP might trigger migraine remain speculative, recent advances with mouse models provide some hints. This brief review focuses on how CGRP might act as both a central and peripheral neuromodulator to contribute to the migraine-like symptom of light aversive behaviour in mice.
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Affiliation(s)
- Andrew F Russo
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA, 52242, USA.,Department of Neurology, University of Iowa, Iowa City, IA, 52242, USA.,Veterans Affairs Medical Center, Iowa City, IA, 52246, USA
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Nag K, Sultana N, Kato A, Dranik A, Nakamura N, Kutsuzawa K, Hirose S, Akaike T. Ligand-induced internalization, recycling, and resensitization of adrenomedullin receptors depend not on CLR or RAMP alone but on the receptor complex as a whole. Gen Comp Endocrinol 2015; 212:156-62. [PMID: 24815888 DOI: 10.1016/j.ygcen.2014.04.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 04/28/2014] [Indexed: 11/24/2022]
Abstract
Adrenomedullins (AM) is a multifaceted distinct subfamily of peptides that belongs to the calcitonin gene-related peptide (CGRP) superfamily. These peptides exert their functional activities via associations of calcitonin receptor-like receptors (CLRs) and receptor activity-modifying proteins (RAMPs) RAMP2 and RAMP3. Recent studies established that RAMPs and CLRs can modify biochemical properties such as trafficking and glycosylation of each other. However there is very little or no understanding regarding how RAMP or CLR influence ligand-induced events of AM-receptor complex. In this study, using pufferfish homologs of CLR (mfCLR1-3) and RAMP (mfRAMP2 and mfRAMP3), we revealed that all combinations of CLR and RAMP quickly underwent ligand-induced internalization; however, their recycling rates were different as follows: mfCLR1-mfRAMP3>mfCLR2-mfRAMP3>mfCLR3-mfRAMP3. Functional receptor assay confirmed that the recycled receptors were resensitized on the plasma membrane. In contrast, a negligible amount of mfCLR1-mfRAMP2 was recycled and reconstituted. Immunocytochemistry results indicated that the lower recovery rate of mfCLR3-mfRAMP3 and mfCLR1-mfRAMP2 was correlated with higher proportion of lysosomal localization of these receptor complexes compared to the other combinations. Collectively our results indicate, for the first time, that the ligand-induced internalization, recycling, and reconstitution properties of RAMP-CLR receptor complexes depend on the receptor-complex as a whole, and not on individual CLR or RAMP alone.
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Affiliation(s)
- Kakon Nag
- Department of Biological Sciences, Tokyo Institute of Technology, 4259-B19 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan; Department of Pathology and Molecular Medicine, McMaster University, 1200 Main St. W. Hamilton, ON L8N 3Z5, Canada; Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259-B19 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan.
| | - Naznin Sultana
- Department of Biological Sciences, Tokyo Institute of Technology, 4259-B19 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan
| | - Akira Kato
- Department of Biological Sciences, Tokyo Institute of Technology, 4259-B19 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan
| | - Anna Dranik
- Department of Pathology and Molecular Medicine, McMaster University, 1200 Main St. W. Hamilton, ON L8N 3Z5, Canada
| | - Nobuhiro Nakamura
- Department of Biological Sciences, Tokyo Institute of Technology, 4259-B19 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan
| | - Koichi Kutsuzawa
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259-B19 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan
| | - Shigehisa Hirose
- Department of Biological Sciences, Tokyo Institute of Technology, 4259-B19 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan
| | - Toshihiro Akaike
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259-B19 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan
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Nguyen PT, Andraka N, De Carufel CA, Bourgault S. Mechanistic Contributions of Biological Cofactors in Islet Amyloid Polypeptide Amyloidogenesis. J Diabetes Res 2015; 2015:515307. [PMID: 26576436 PMCID: PMC4630397 DOI: 10.1155/2015/515307] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 01/26/2015] [Accepted: 02/09/2015] [Indexed: 01/24/2023] Open
Abstract
Type II diabetes mellitus is associated with the deposition of fibrillar aggregates in pancreatic islets. The major protein component of islet amyloids is the glucomodulatory hormone islet amyloid polypeptide (IAPP). Islet amyloid fibrils are virtually always associated with several biomolecules, including apolipoprotein E, metals, glycosaminoglycans, and various lipids. IAPP amyloidogenesis has been originally perceived as a self-assembly homogeneous process in which the inherent aggregation propensity of the peptide and its local concentration constitute the major driving forces to fibrillization. However, over the last two decades, numerous studies have shown a prominent role of amyloid cofactors in IAPP fibrillogenesis associated with the etiology of type II diabetes. It is increasingly evident that the biochemical microenvironment in which IAPP amyloid formation occurs and the interactions of the polypeptide with various biomolecules not only modulate the rate and extent of aggregation, but could also remodel the amyloidogenesis process as well as the structure, toxicity, and stability of the resulting fibrils.
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Affiliation(s)
- Phuong Trang Nguyen
- Department of Chemistry, Pharmaqam, University of Quebec in Montreal, Montreal, QC, Canada H3C 3P8
- Quebec Network for Research on Protein Function, Structure, and Engineering (PROTEO), Canada
| | - Nagore Andraka
- Department of Chemistry, Pharmaqam, University of Quebec in Montreal, Montreal, QC, Canada H3C 3P8
- Quebec Network for Research on Protein Function, Structure, and Engineering (PROTEO), Canada
- Biophysics Unit (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, University of the Basque Country, 48080 Bilbao, Spain
| | - Carole Anne De Carufel
- Department of Chemistry, Pharmaqam, University of Quebec in Montreal, Montreal, QC, Canada H3C 3P8
- Quebec Network for Research on Protein Function, Structure, and Engineering (PROTEO), Canada
| | - Steve Bourgault
- Department of Chemistry, Pharmaqam, University of Quebec in Montreal, Montreal, QC, Canada H3C 3P8
- Quebec Network for Research on Protein Function, Structure, and Engineering (PROTEO), Canada
- *Steve Bourgault:
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Abstract
Migraine is a neurological disorder that manifests as a debilitating headache associated with altered sensory perception. The neuropeptide calcitonin gene-related peptide (CGRP) is now firmly established as a key player in migraine. Clinical trials carried out during the past decade have proved that CGRP receptor antagonists are effective for treating migraine, and antibodies to the receptor and CGRP are currently under investigation. Despite this progress in the clinical arena, the mechanisms by which CGRP triggers migraine remain uncertain. This review discusses mechanisms whereby CGRP enhances sensitivity to sensory input at multiple levels in both the periphery and central nervous system. Future studies on epistatic and epigenetic regulators of CGRP actions are expected to shed further light on CGRP actions in migraine. In conclusion, targeting CGRP represents an approachable therapeutic strategy for migraine.
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Watkins HA, Walker CS, Ly KN, Bailey RJ, Barwell J, Poyner DR, Hay DL. Receptor activity-modifying protein-dependent effects of mutations in the calcitonin receptor-like receptor: implications for adrenomedullin and calcitonin gene-related peptide pharmacology. Br J Pharmacol 2014; 171:772-88. [PMID: 24199627 PMCID: PMC3969088 DOI: 10.1111/bph.12508] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 10/22/2013] [Accepted: 10/30/2013] [Indexed: 01/22/2023] Open
Abstract
Background and Purpose Receptor activity-modifying proteins (RAMPs) define the pharmacology of the calcitonin receptor-like receptor (CLR). The interactions of the different RAMPs with this class B GPCR yield high-affinity calcitonin gene-related peptide (CGRP) or adrenomedullin (AM) receptors. However, the mechanism for this is unclear. Experimental Approach Guided by receptor models, we mutated residues in the N-terminal helix of CLR, RAMP2 and RAMP3 hypothesized to be involved in peptide interactions. These were assayed for cAMP production with AM, AM2 and CGRP together with their cell surface expression. Binding studies were also conducted for selected mutants. Key Results An important domain for peptide interactions on CLR from I32 to I52 was defined. Although I41 was universally important for binding and receptor function, the role of other residues depended on both ligand and RAMP. Peptide binding to CLR/RAMP3 involved a more restricted range of residues than that to CLR/RAMP1 or CLR/RAMP2. E101 of RAMP2 had a major role in AM interactions, and F111/W84 of RAMP2/3 was important with each peptide. Conclusions and Implications RAMP-dependent effects of CLR mutations suggest that the different RAMPs control accessibility of peptides to binding residues situated on the CLR N-terminus. RAMP3 appears to alter the role of specific residues at the CLR-RAMP interface compared with RAMP1 and RAMP2.
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Affiliation(s)
- H A Watkins
- School of Biological Sciences, University of Auckland, Auckland, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand
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Vécsei L, Szok D, Csáti A, Tajti J. CGRP antagonists and antibodies for the treatment of migraine. Expert Opin Investig Drugs 2014; 24:31-41. [DOI: 10.1517/13543784.2015.960921] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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White S, Marquez de Prado B, Russo AF, Hammond DL. Heat hyperalgesia and mechanical hypersensitivity induced by calcitonin gene-related peptide in a mouse model of neurofibromatosis. PLoS One 2014; 9:e106767. [PMID: 25184332 PMCID: PMC4153688 DOI: 10.1371/journal.pone.0106767] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 08/08/2014] [Indexed: 11/21/2022] Open
Abstract
This study examined whether mice with a deficiency of neurofibromin, a Ras GTPase activating protein, exhibit a nociceptive phenotype and probed a possible contribution by calcitonin gene-related peptide. In the absence of inflammation, Nf1+/− mice (B6.129S6 Nf1<tm1Fcr>/J) and wild type littermates responded comparably to heat or mechanical stimuli, except for a subtle enhanced mechanical sensitivity in female Nf1+/− mice. Nociceptive phenotype was also examined after inflammation induced by capsaicin and formalin, which release endogenous calcitonin gene-related peptide. Intraplantar injection of capsaicin evoked comparable heat hyperalgesia and mechanical hypersensitivity in Nf1+/− and wild type mice of both genders. Formalin injection caused a similar duration of licking in male Nf1+/− and wild type mice. Female Nf1+/− mice licked less than wild type mice, but displayed other nociceptive behaviors. In contrast, intraplantar injection of CGRP caused greater heat hyperalgesia in Nf1+/− mice of both genders compared to wild type mice. Male Nf1+/− mice also exhibited greater mechanical hypersensitivity; however, female Nf1+/− mice exhibited less mechanical hypersensitivity than their wild type littermates. Transcripts for calcitonin gene-related peptide were similar in the dorsal root ganglia of both genotypes and genders. Transcripts for receptor activity-modifying protein-1, which is rate-limiting for the calcitonin gene-related peptide receptor, in the spinal cord were comparable for both genotypes and genders. The increased responsiveness to intraplantar calcitonin gene-related peptide suggests that the peripheral actions of calcitonin gene-related peptide are enhanced as a result of the neurofibromin deficit. The analgesic efficacy of calcitonin gene-related peptide receptor antagonists may therefore merit investigation in neurofibromatosis patients.
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Affiliation(s)
- Stephanie White
- Department of Anesthesia, University of Iowa, Iowa City, Iowa, United States of America
| | - Blanca Marquez de Prado
- Department of Anesthesia, University of Iowa, Iowa City, Iowa, United States of America
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa, United States of America
| | - Andrew F. Russo
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa, United States of America
| | - Donna L. Hammond
- Department of Anesthesia, University of Iowa, Iowa City, Iowa, United States of America
- Department of Pharmacology, University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
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Understanding and exploiting 5T4 oncofoetal glycoprotein expression. Semin Cancer Biol 2014; 29:13-20. [PMID: 25066861 DOI: 10.1016/j.semcancer.2014.07.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 07/17/2014] [Indexed: 01/14/2023]
Abstract
Oncofoetal antigens are present during foetal development with generally limited expression in the adult but are upregulated in cancer. These molecules can sometimes be used to diagnose or follow treatment of tumours or as a target for different immunotherapies. The 5T4 oncofoetal glycoprotein was identified by searching for shared surface molecules of human trophoblast and cancer cells with the rationale that they may function to allow survival of the foetus as a semi-allograft in the mother or a tumour in its host, potentially influencing growth, invasion or altered immune surveillance of the host. 5T4 tumour selective expression has stimulated the development of 5T4 vaccine, 5T4 antibody targeted-superantigen and 5T4 antibody-drug therapies through preclinical and into clinical studies. It is now apparent that 5T4 expression is a marker of the use (or not) of several cellular pathways relevant to tumour growth and spread. Thus 5T4 expression is mechanistically associated with the directional movement of cells through epithelial mesenchymal transition, facilitation of CXCL12/CXCR4 chemotaxis, blocking of canonical Wnt/beta-catenin while favouring non-canonical pathway signalling. These processes are highly regulated in development and in normal adult tissues but can contribute to the spread of cancer cells. Understanding the differential impact of these pathways marked by 5T4 can potentially improve existing, or aid development of novel cancer treatment strategies.
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61
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Christopoulos A. Advances in G protein-coupled receptor allostery: from function to structure. Mol Pharmacol 2014; 86:463-78. [PMID: 25061106 DOI: 10.1124/mol.114.094342] [Citation(s) in RCA: 170] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
It is now widely accepted that G protein-coupled receptors (GPCRs) are highly dynamic proteins that adopt multiple active states linked to distinct functional outcomes. Furthermore, these states can be differentially stabilized not only by orthosteric ligands but also by allosteric ligands acting at spatially distinct binding sites. The key pharmacologic characteristics of GPCR allostery include improved selectivity due to either greater sequence divergence between receptor subtypes and/or subtype-selective cooperativity, a ceiling level to the effect, probe dependence (whereby the magnitude and direction of the allosteric effect change with the nature of the interacting ligands), and the potential for biased signaling. Recent chemical biology developments are beginning to demonstrate how the incorporation of analytical pharmacology and operational modeling into the experimental workflow can enrich structure-activity studies of allostery and bias, and have also led to the discovery of a new class of hybrid orthosteric/allosteric (bitopic) molecules. The potential for endogenous allosteric modulators to play a role in physiology and disease remains to be fully appreciated but will likely represent an important area for future studies. Finally, breakthroughs in structural and computational biology are beginning to unravel the mechanistic basis of GPCR allosteric modulation at the molecular level.
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Affiliation(s)
- Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia
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62
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What is pharmacological 'affinity'? Relevance to biased agonism and antagonism. Trends Pharmacol Sci 2014; 35:434-41. [PMID: 25042457 DOI: 10.1016/j.tips.2014.06.003] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 06/16/2014] [Accepted: 06/17/2014] [Indexed: 11/22/2022]
Abstract
The differences between affinity measurements made in binding studies and those relevant to receptor function are described. There are theoretical and practical reasons for not utilizing binding data and, in terms of the quantification of signaling bias, it is unnecessary to do so. Finally, the allosteric control of ligand affinity through receptor-signaling protein interaction is discussed within the context of biased antagonism. In this regard, it is shown that both the bias and relative efficacy of a ligand are essential data for fully predicting biased effects in vivo.
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Chadha PS, Jepps TA, Carr G, Stott JB, Zhu HL, Cole WC, Greenwood IA. Contribution of kv7.4/kv7.5 heteromers to intrinsic and calcitonin gene-related peptide-induced cerebral reactivity. Arterioscler Thromb Vasc Biol 2014; 34:887-93. [PMID: 24558103 DOI: 10.1161/atvbaha.114.303405] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
OBJECTIVE Middle cerebral artery (MCA) diameter is regulated by inherent myogenic activity and the effect of potent vasodilators such as calcitonin gene-related peptide (CGRP). Previous studies showed that MCAs express KCNQ1, 4, and 5 potassium channel genes, and the expression products (Kv7 channels) participate in the myogenic control of MCA diameter. The present study investigated the contribution of Kv7.4 and Kv7.5 isoforms to myogenic and CGRP regulation of MCA diameter and determined whether they were affected in hypertensive animals. APPROACH AND RESULTS Isometric tension recordings performed on MCA from normotensive rats produced CGRP vasodilations that were inhibited by the pan-Kv7 channel blocker linopirdine (P<0.01) and after transfection of arteries with siRNA against KCNQ4 (P<0.01) but not KCNQ5. However, isobaric myography revealed that myogenic constriction in response to increases in intravascular pressure (20-80 mm Hg) was affected by both KCNQ4 and KCNQ5 siRNA. Proximity ligation assay signals were equally abundant for Kv7.4/Kv7.4 or Kv7.4/Kv7.5 antibody combinations but minimal for Kv7.5/Kv7.5 antibodies or Kv7.4/7.1 combinations. In contrast to systemic arteries, Kv7 function and Kv7.4 abundance in MCA were not altered in hypertensive rats. CONCLUSIONS This study reveals, for the first time to our knowledge, that in cerebral arteries, Kv7.4 and Kv7.5 proteins exist predominantly as a functional heterotetramer, which regulates intrinsic myogenicity and vasodilation attributed to CGRP. Surprisingly, unlike systemic arteries, Kv7 activity in MCAs is not affected by the development of hypertension, and CGRP-mediated vasodilation is well maintained. As such, cerebrovascular Kv7 channels could be amenable for therapeutic targeting in conditions such as cerebral vasospasm.
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Affiliation(s)
- Preet S Chadha
- From the Division of Biomedical Sciences, Pharmacology and Cell Physiology Research Group, St George's University of London, London, United Kingdom (P.S.C., T.A.J., G.C., J.B.S., I.A.G.); and The Smooth Muscle Research Group, Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada (H.-L.Z., W.C.C.)
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Adrenomedullin-RAMP2 system suppresses ER stress-induced tubule cell death and is involved in kidney protection. PLoS One 2014; 9:e87667. [PMID: 24505304 PMCID: PMC3914859 DOI: 10.1371/journal.pone.0087667] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Accepted: 12/29/2013] [Indexed: 11/19/2022] Open
Abstract
Various bioactive peptides have been implicated in the homeostasis of organs and tissues. Adrenomedullin (AM) is a peptide with various bioactivities. AM-receptor, calcitonin-receptor-like receptor (CLR) associates with one of the subtypes of the accessory proteins, RAMPs. Among the RAMP subisoforms, only RAMP2 knockout mice (−/−) reproduce the phenotype of embryonic lethality of AM−/−, illustrating the importance of the AM-RAMP2-signaling system. Although AM and RAMP2 are abundantly expressed in kidney, their function there remains largely unknown. We used genetically modified mice to assess the pathophysiological functions of the AM-RAMP2 system. RAMP2+/− mice and their wild-type littermates were used in a streptozotocin (STZ)-induced renal injury model. The effect of STZ on glomeruli did not differ between the 2 types of mice. On the other hand, damage to the proximal urinary tubules was greater in RAMP2+/−. Tubular injury in RAMP2+/− was resistant to correction of blood glucose by insulin administration. We examined the effect of STZ on human renal proximal tubule epithelial cells (RPTECs), which express glucose transporter 2 (GLUT2), the glucose transporter that specifically takes up STZ. STZ activated the endoplasmic reticulum (ER) stress sensor protein kinase RNA-like endoplasmic reticulum kinase (PERK). AM suppressed PERK activation, its downstream signaling, and CCAAT/enhancer-binding homologous protein (CHOP)-induced cell death. We confirmed that the tubular damage was caused by ER stress-induced cell death using tunicamycin (TUN), which directly evokes ER stress. In RAMP2+/− kidneys, TUN caused severe injury with enhanced ER stress. In wild-type mice, TUN-induced tubular damage was reversed by AM administration. On the other hand, in RAMP2+/−, the rescue effect of exogenous AM was lost. These results indicate that the AM-RAMP2 system suppresses ER stress-induced tubule cell death, thereby exerting a protective effect on kidney. The AM-RAMP2 system thus has the potential to serve as a therapeutic target in kidney disease.
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Shi B, Long X, Zhao R, Liu Z, Wang D, Xu G. Transplantation of mesenchymal stem cells carrying the human receptor activity-modifying protein 1 gene improves cardiac function and inhibits neointimal proliferation in the carotid angioplasty and myocardial infarction rabbit model. Exp Biol Med (Maywood) 2014; 239:356-65. [PMID: 24477823 DOI: 10.1177/1535370213517619] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Although transplanting mesenchymal stem cells (MSCs) can improve cardiac function and contribute to endothelial recovery in a damaged artery, natural MSCs may induce neointimal hyperplasia by directly or indirectly acting on vascular smooth muscle cells (VSMCs). Receptor activity-modifying protein 1 (RAMP1) is the component and the determinant of ligand specificity of calcitonin gene-related peptide (CGRP). It is recently reported that CGRP and its receptor involve the proliferation and the apoptosis in vivo and in vitro, and the exogenous RAMP1 enhances the antiproliferation effect of CGRP in VSMCs. Here, we investigated the effects of MSCs overexpressing the human receptor activity-modifying protein 1 (hRAMP1) on heart function and artery repair in rabbit models of myocardial infarction (MI) reperfusion and carotid artery injury. MSCs transfected with a recombinant adenovirus containing the hRAMP1 gene (EGFP-hRAMP1-MSCs) were injected into the rabbit models via the ear vein at 24 h after carotid artery injury and MI 7 days post-EGFP-hRAMP1-MSC transplantation. The cells that expressed both enhance green fluorescent protein (EGFP) and CD31 were detected in the neointima of the damaged artery via immunofluorescence. EGFP-hRAMP1 expression was observed in the injured artery and infarcted myocardium by western blot analysis, confirming that the engineered MSCs targeted the injured artery and infarcted myocardium and expressed hRAMP1 protein. Compared with the EGFP-MSCs group, the EGFP-hRAMP1-MSCs group had a significantly smaller infarcted area and improved cardiac function by 28 days after cell transplantation, as detected by triphenyltetrazolium chloride staining and echocardiography. Additionally, arterial hematoxylin-eosin staining revealed that the area of the neointima and the area ratio of intima/media were significantly decreased in the EGFP-hRAMP1-MSCs group. An immunohistological study showed that the expression of α-smooth muscle antigen and proliferating cell nuclear antigen in the neointima cells of the carotid artery of the EGFP-hRAMP1-MSCs group was approximately 50% lower than that of the EGFP-MSCs group, suggesting that hRAMP1 expression may inhibit VSMCs proliferation within the neointima. Therefore, compared with natural MSCs, EGFP-hRAMP1-engineered MSCs improved infarcted heart function and endothelial recovery from artery injury more efficiently, which will provide valuable information for the development of MSC-based therapy.
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Affiliation(s)
- Bei Shi
- Department of Cardiology, the First Affiliated Hospital of Zunyi Medical College, Zunyi City 563003, Guizhou Province, China
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Abstract
Obesity and its related metabolic consequences represent a major public health problem. Huge changes within the environment have undoubtedly contributed to the increased prevalence of obesity but genetic factors are also critical in determining an individual's predisposition to gain weight. The last two decades have seen a huge increase in the understanding of the mechanisms controlling appetitive behavior, body composition, and energy expenditure. Many regions throughout the central nervous system play critical roles in these processes but the hypothalamus, in particular, receives and orchestrates a variety of signals to bring about coordinated changes in energy balance. Reviewing data from human genetic and model organism studies, we consider how disruptions of hypothalamic pathways evolved to maintain energy homeostasis and go on to cause obesity. We highlight ongoing technological developments which continue to lead to novel insights and discuss how this increased knowledge may lead to effective therapeutic interventions in the future.
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Affiliation(s)
- Rachel Larder
- University of Cambridge Metabolic Research Laboratories, MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, UK
| | - Chung Thong Lim
- University of Cambridge Metabolic Research Laboratories, MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, UK
| | - Anthony P Coll
- University of Cambridge Metabolic Research Laboratories, MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, UK.
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Heng BC, Aubel D, Fussenegger M. An overview of the diverse roles of G-protein coupled receptors (GPCRs) in the pathophysiology of various human diseases. Biotechnol Adv 2013; 31:1676-94. [DOI: 10.1016/j.biotechadv.2013.08.017] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 08/19/2013] [Accepted: 08/19/2013] [Indexed: 12/23/2022]
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Um JW, Kaufman AC, Kostylev M, Heiss JK, Stagi M, Takahashi H, Kerrisk ME, Vortmeyer A, Wisniewski T, Koleske AJ, Gunther EC, Nygaard HB, Strittmatter SM. Metabotropic glutamate receptor 5 is a coreceptor for Alzheimer aβ oligomer bound to cellular prion protein. Neuron 2013; 79:887-902. [PMID: 24012003 DOI: 10.1016/j.neuron.2013.06.036] [Citation(s) in RCA: 435] [Impact Index Per Article: 39.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/17/2013] [Indexed: 02/07/2023]
Abstract
Soluble amyloid-β oligomers (Aβo) trigger Alzheimer's disease (AD) pathophysiology and bind with high affinity to cellular prion protein (PrP(C)). At the postsynaptic density (PSD), extracellular Aβo bound to lipid-anchored PrP(C) activates intracellular Fyn kinase to disrupt synapses. Here, we screened transmembrane PSD proteins heterologously for the ability to couple Aβo-PrP(C) with Fyn. Only coexpression of the metabotropic glutamate receptor, mGluR5, allowed PrP(C)-bound Aβo to activate Fyn. PrP(C) and mGluR5 interact physically, and cytoplasmic Fyn forms a complex with mGluR5. Aβo-PrP(C) generates mGluR5-mediated increases of intracellular calcium in Xenopus oocytes and in neurons, and the latter is also driven by human AD brain extracts. In addition, signaling by Aβo-PrP(C)-mGluR5 complexes mediates eEF2 phosphorylation and dendritic spine loss. For mice expressing familial AD transgenes, mGluR5 antagonism reverses deficits in learning, memory, and synapse density. Thus, Aβo-PrP(C) complexes at the neuronal surface activate mGluR5 to disrupt neuronal function.
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Affiliation(s)
- Ji Won Um
- Cellular Neuroscience, Neurodegeneration and Repair Program, Departments of Neurology and Neurobiology, Yale University School of Medicine, New Haven, CT 06536, USA
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Heng BC, Aubel D, Fussenegger M. G protein-coupled receptors revisited: therapeutic applications inspired by synthetic biology. Annu Rev Pharmacol Toxicol 2013; 54:227-49. [PMID: 24160705 DOI: 10.1146/annurev-pharmtox-011613-135921] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
G protein-coupled receptors (GPCRs) mediate the majority of cellular responses to hormones and neurotransmitters within the human body. They have much potential in the emerging field of synthetic biology, which is the rational, systematic design of biological systems with desired functionality. The responsiveness of GPCRs to a plethora of endogenous and exogenous ligands and stimuli make them ideal sensory receptor modules of synthetic gene networks. Such networks can activate target gene expression in response to a specific stimulus. Additionally, because GPCRs are important pharmacological targets of various human diseases, genes encoding their protein/peptide ligands can also be incorporated as target genes of the response output elements of synthetic gene networks. This review aims to critically examine the potential role of GPCRs in constructing therapeutic synthetic gene networks and to discuss various challenges in utilizing GPCRs for synthetic biology applications.
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Affiliation(s)
- Boon Chin Heng
- Department of Biosystems Science and Engineering, ETH Zürich, CH-4058 Basel, Switzerland;
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70
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Asai M, Ramachandrappa S, Joachim M, Shen Y, Zhang R, Nuthalapati N, Ramanathan V, Strochlic DE, Ferket P, Linhart K, Ho C, Novoselova TV, Garg S, Ridderstråle M, Marcus C, Hirschhorn JN, Keogh JM, O’Rahilly S, Chan LF, Clark AJ, Farooqi IS, Majzoub JA. Loss of function of the melanocortin 2 receptor accessory protein 2 is associated with mammalian obesity. Science 2013; 341:275-8. [PMID: 23869016 PMCID: PMC3788688 DOI: 10.1126/science.1233000] [Citation(s) in RCA: 188] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Melanocortin receptor accessory proteins (MRAPs) modulate signaling of melanocortin receptors in vitro. To investigate the physiological role of brain-expressed melanocortin 2 receptor accessory protein 2 (MRAP2), we characterized mice with whole-body and brain-specific targeted deletion of Mrap2, both of which develop severe obesity at a young age. Mrap2 interacts directly with melanocortin 4 receptor (Mc4r), a protein previously implicated in mammalian obesity, and it enhances Mc4r-mediated generation of the second messenger cyclic adenosine monophosphate, suggesting that alterations in Mc4r signaling may be one mechanism underlying the association between Mrap2 disruption and obesity. In a study of humans with severe, early-onset obesity, we found four rare, potentially pathogenic genetic variants in MRAP2, suggesting that the gene may also contribute to body weight regulation in humans.
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Affiliation(s)
- Masato Asai
- Division of Endocrinology, Department of Medicine, Boston Children’s Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115
- Departments of Pathology, Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Shwetha Ramachandrappa
- University of Cambridge Metabolic Research Laboratories and NIHR Cambridge Biomedical Research Centre, Institute of Metabolic Science, Addenbrooke’s Hospital, CB2 0QQ, Cambridge, UK
| | - Maria Joachim
- Division of Endocrinology, Department of Medicine, Boston Children’s Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115
| | - Yuan Shen
- Division of Endocrinology, Department of Medicine, Boston Children’s Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115
| | - Rong Zhang
- Division of Endocrinology, Department of Medicine, Boston Children’s Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115
| | - Nikhil Nuthalapati
- Division of Endocrinology, Department of Medicine, Boston Children’s Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115
| | - Visali Ramanathan
- Division of Endocrinology, Department of Medicine, Boston Children’s Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115
| | - David E. Strochlic
- Division of Endocrinology, Department of Medicine, Boston Children’s Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115
| | - Peter Ferket
- Prestage Department of Poultry Science, North Carolina State University, Raleigh, NC 27695
| | - Kirsten Linhart
- Division of Endocrinology, Department of Medicine, Boston Children’s Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115
| | - Caroline Ho
- Division of Endocrinology, Department of Medicine, Boston Children’s Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115
| | - Tatiana V. Novoselova
- William Harvey Research Institute, Centre for Endocrinology Queen Mary, University of London Barts and The London School of Medicine and Dentistry, London, EC1M 6BQ, UK
| | - Sumedha Garg
- University of Cambridge Metabolic Research Laboratories and NIHR Cambridge Biomedical Research Centre, Institute of Metabolic Science, Addenbrooke’s Hospital, CB2 0QQ, Cambridge, UK
| | - Martin Ridderstråle
- Department of Clinical Sciences, Lund University, Malmö, Sweden and Steno Diabetes Center, Gentofte, Denmark
| | - Claude Marcus
- Department for Clinical Science, Intervention and Technology, Karolinska Institute, Division of Pediatrics, National Childhood Obesity Centre, Stockholm, Sweden
| | - Joel N. Hirschhorn
- Division of Endocrinology, Department of Medicine, Boston Children’s Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115
- Department of Genetics, Harvard Medical School and Broad Institute, Cambridge, MA
| | - Julia M. Keogh
- University of Cambridge Metabolic Research Laboratories and NIHR Cambridge Biomedical Research Centre, Institute of Metabolic Science, Addenbrooke’s Hospital, CB2 0QQ, Cambridge, UK
| | - Stephen O’Rahilly
- University of Cambridge Metabolic Research Laboratories and NIHR Cambridge Biomedical Research Centre, Institute of Metabolic Science, Addenbrooke’s Hospital, CB2 0QQ, Cambridge, UK
| | - Li F. Chan
- William Harvey Research Institute, Centre for Endocrinology Queen Mary, University of London Barts and The London School of Medicine and Dentistry, London, EC1M 6BQ, UK
| | - Adrian J. Clark
- William Harvey Research Institute, Centre for Endocrinology Queen Mary, University of London Barts and The London School of Medicine and Dentistry, London, EC1M 6BQ, UK
| | - I. Sadaf Farooqi
- University of Cambridge Metabolic Research Laboratories and NIHR Cambridge Biomedical Research Centre, Institute of Metabolic Science, Addenbrooke’s Hospital, CB2 0QQ, Cambridge, UK
| | - Joseph A. Majzoub
- Division of Endocrinology, Department of Medicine, Boston Children’s Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115
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Wootten D, Lindmark H, Kadmiel M, Willcockson H, Caron KM, Barwell J, Drmota T, Poyner DR. Receptor activity modifying proteins (RAMPs) interact with the VPAC2 receptor and CRF1 receptors and modulate their function. Br J Pharmacol 2013; 168:822-34. [PMID: 22946657 DOI: 10.1111/j.1476-5381.2012.02202.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 08/15/2012] [Accepted: 08/28/2012] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND AND PURPOSE Although it is established that the receptor activity modifying proteins (RAMPs) can interact with a number of GPCRs, little is known about the consequences of these interactions. Here the interaction of RAMPs with the glucagon-like peptide 1 receptor (GLP-1 receptor), the human vasoactive intestinal polypeptide/pituitary AC-activating peptide 2 receptor (VPAC(2)) and the type 1 corticotrophin releasing factor receptor (CRF(1)) has been examined. EXPERIMENTAL APPROACH GPCRs were co-transfected with RAMPs in HEK 293S and CHO-K1 cells. Cell surface expression of RAMPs and GPCRs was examined by ELISA. Where there was evidence for interactions, agonist-stimulated cAMP production, Ca(2+) mobilization and GTPγS binding to G(s), G(i), G(12) and G(q) were examined. The ability of CRF to stimulate adrenal corticotrophic hormone release in Ramp2(+/-) mice was assessed. KEY RESULTS The GLP-1 receptor failed to enhance the cell surface expression of any RAMP. VPAC(2) enhanced the cell surface expression of all three RAMPs. CRF(1) enhanced the cell surface expression of RAMP2; the cell surface expression of CRF(1) was also increased. There was no effect on agonist-stimulated cAMP production. However, there was enhanced G-protein coupling in a receptor and agonist-dependent manner. The CRF(1) : RAMP2 complex resulted in enhanced elevation of intracellular calcium to CRF and urocortin 1 but not sauvagine. In Ramp2(+/-) mice, there was a loss of responsiveness to CRF. CONCLUSIONS AND IMPLICATIONS The VPAC(2) and CRF(1) receptors interact with RAMPs. This modulates G-protein coupling in an agonist-specific manner. For CRF(1), coupling to RAMP2 may be of physiological significance.
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Affiliation(s)
- D Wootten
- School of Life and Health Sciences, Aston University, Birmingham, UK
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72
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Fernandes-Santos C, Zhang Z, Morgan DA, Guo DF, Russo AF, Rahmouni K. Amylin acts in the central nervous system to increase sympathetic nerve activity. Endocrinology 2013; 154:2481-8. [PMID: 23645151 PMCID: PMC3689285 DOI: 10.1210/en.2012-2172] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The pancreatic hormone amylin acts in the central nervous system (CNS) to decrease food intake and body weight. We hypothesized that amylin action in the CNS promotes energy expenditure by increasing the activity of the sympathetic nervous system. In mice, ip administration of amylin significantly increased c-Fos immunoreactivity in hypothalamic and brainstem nuclei. In addition, mice treated with intracerebroventricular (icv) amylin (0.1 and 0.2 nmol) exhibited a dose-related decrease in food intake and body weight, measured 4 and 24 hours after treatment. The icv injection of amylin also increased body temperature in mice. Using direct multifiber sympathetic nerve recording, we found that icv amylin elicited a significant and dose-dependent increase in sympathetic nerve activity (SNA) subserving thermogenic brown adipose tissue (BAT). Of note, icv injection of amylin also evoked a significant and dose-related increase in lumbar and renal SNA. Importantly, icv pretreatment with the amylin receptor antagonist AC187 (20 nmol) abolished the BAT SNA response induced by icv amylin, indicating that the sympathetic effects of amylin are receptor-mediated. Conversely, icv amylin-induced BAT SNA response was enhanced in mice overexpressing the amylin receptor subunit, RAMP1 (receptor-activity modifying protein 1), in the CNS. Our data demonstrate that CNS action of amylin regulates sympathetic nerve outflow to peripheral tissues involved in energy balance and cardiovascular function.
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Affiliation(s)
- Caroline Fernandes-Santos
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
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73
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Zhao Z, Fu X, Zhang G, Li Y, Wu M, Tan Y. The influence of RAMP1 overexpression on CGRP-induced osteogenic differentiation in MG-63 cells in vitro: an experimental study. J Cell Biochem 2013; 114:314-22. [PMID: 22949393 DOI: 10.1002/jcb.24375] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2012] [Accepted: 08/13/2012] [Indexed: 11/10/2022]
Abstract
The aim of this study was to elucidate the influence of receptor activity modifying protein 1 (RAMP1) overexpression on the expression and distribution of calcitonin receptor-like receptor (CRLR) in MG-63 cells. Our research also focused on whether RAMP1 overexpression enhanced the promoting effect of exogenous CGRP on osteogenic differentiation in MG-63 cells. We first constructed a eukaryotic expression vector containing human RAMP1 and stably transfected it into MG-63 cells. Real-time PCR and Western blotting were used to determine the expression levels of RAMP1 and CRLR mRNA and protein, respectively. Immunofluorescence analysis was employed to compare the distribution of CRLR in transfected cells. After treatment with CGRP, the extent of osteogenic differentiation was evaluated by simultaneous monitoring of alkaline phosphatase activity, the expression patterns of osteoblastic markers and mineralisation staining. We found that RAMP1 was more highly expressed in the transfected group compared with the control groups (P < 0.01). The CRLR expression was significantly higher than that in the control groups (P < 0.05). In addition, after 7 days of CGRP treatment to induce osteogenic differentiation, the expression of collagen I mRNA was markedly increased in the transfected group (P < 0.05). The transfected group exhibited more granular precipitation in the cytoplasm with alkaline phosphatase staining after 7 and 14 days of differentiation. When stained with Alizarin Red, cells overexpressing RAMP1 were darker and formed many mineralised nodules with clear boundaries and calcium deposition typical of mineralised bone matrix structures at 28 days post-induction of differentiation. The CGRP-induced ALP activity in the RAMP1 overexpression group was significantly higher 3, 6 and 9 days after induction than that in the two control groups (P < 0.05). RAMP1 overexpression promotes CRLR expression, localisation on the cell membrane and enhanced CGRP-mediated differentiation of MG-63 cells. This study contributes to a better understanding of the molecular mechanisms governing CGRP-induced MG-63 differentiation.
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Affiliation(s)
- Zhiliang Zhao
- Department of Oral and Maxillofacial Surgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, PR China
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74
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Erdling A, Sheykhzade M, Maddahi A, Bari F, Edvinsson L. VIP/PACAP receptors in cerebral arteries of rat: characterization, localization and relation to intracellular calcium. Neuropeptides 2013; 47:85-92. [PMID: 23375386 DOI: 10.1016/j.npep.2012.12.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Revised: 12/18/2012] [Accepted: 12/23/2012] [Indexed: 01/28/2023]
Abstract
BACKGROUND Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase activating peptide (PACAP)-containing nerves surround cerebral blood vessels. The peptides have potent vasodilator properties via smooth muscle cell receptors and activation of adenylate cyclase. The purpose of this study was to describe the effects of two putative VIP/PACAP receptor antagonists and the distribution of the receptor protein in rat brain vessels. METHODS The vascular effects of VIP, PACAP-27 and PACAP-38 were investigated in segments of rat middle cerebral artery (MCA) by pressurized arteriography, and in a wire myograph. The antagonistic responses to PACAP6-38 and PG99-465 were evaluated. In addition, the receptor subtypes for VIP and PACAP (VPAC1, VPAC2 and PAC1) were visualized in the rat middle cerebral artery by immunohistochemistry and Western blotting. RESULTS In the perfusion model, abluminal but not luminal VIP, PACAP-27 and PACAP-38 caused concentration-dependent relaxations of the MCA (27.1±0.2%, 25.2±0.4% and 0.3±0.1%, respectively). In the wire myograph, there was no significant difference in potency of the peptides in the MCA. In both systems, PACAP6-38 and PG99-465 inhibited the VIP induced relaxation. Western blot showed the presence of the receptor proteins in cerebral vasculature and immunohistochemistry showed that all three receptors are present and located in the cytoplasm of smooth muscle cells. CONCLUSION In both systems, the two blockers antagonized the relaxant VIP effect; the potency order of agonists and the immunohistochemistry suggest the presence of the dilatory VPAC1 and VPAC2 receptors on the smooth muscle cells.
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MESH Headings
- 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid/pharmacology
- Angiography
- Animals
- Blotting, Western
- Calcium/physiology
- Cerebral Arteries/drug effects
- Cerebral Arteries/metabolism
- Electromyography
- Fluorescent Antibody Technique
- Immunohistochemistry
- Isometric Contraction/drug effects
- Male
- Muscle, Smooth, Vascular/physiology
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- Rats
- Rats, Sprague-Dawley
- Rats, Wistar
- Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide/drug effects
- Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide/physiology
- Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I/metabolism
- Receptors, Vasoactive Intestinal Peptide/drug effects
- Receptors, Vasoactive Intestinal Peptide/physiology
- Receptors, Vasoactive Intestinal Peptide, Type II/metabolism
- Vasoconstrictor Agents/pharmacology
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Affiliation(s)
- André Erdling
- Department of Clinical Sciences, Division of Experimental Vascular Research, Lund University, Lund, Sweden.
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75
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Benes J, Mravec B, Kvetnansky R, Myslivecek J. The restructuring of muscarinic receptor subtype gene transcripts in c-fos knock-out mice. Brain Res Bull 2013; 94:30-9. [PMID: 23395867 DOI: 10.1016/j.brainresbull.2013.01.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Revised: 01/17/2013] [Accepted: 01/29/2013] [Indexed: 10/27/2022]
Abstract
Although c-Fos plays a key role in intracellular signalling, the disruption of the c-fos gene has only minor consequences on the central nervous system (CNS) function. As muscarinic receptors (MR) play important roles in many CNS functions (attention, arousal, and cognition), the c-fos knock-out might be compensated through MR changes. The aim of this study was to evaluate changes in the M1-M5 MR mRNA in selected CNS areas: frontal, parietal, temporal and occipital cortex, striatum, hippocampus, hypothalamus and cerebellum (FC, PC, TC, OC, stria, hip, hypo, and crbl, respectively). Knocking out the c-fos gene changed the expression of MR in FC (reduced M1R, M4R and M5R expression), TC (increased M4R expression), OC (decreased M2R and M3R expression) and hippocampus (reduced M3R expression). Moreover, gender differences were observed in WT mice: increased expression of all M1-M5R in the FC in males and M1-M4R in the striatum in females. A detailed analysis of MR transcripts showed pre-existing correlations in the amount of MR-mRNA between specific regions. WT mice showed three major types of cortico-cortical correlations: fronto-occipital, temporo-parietal and parieto-occipital. The cortico-subcortical correlations involved associations between the FC, PC, TC and striatum. In KO mice, a substantial rearrangement of the correlation pattern was observed: only a temporo-parietal correlation and correlations between the FC and striatum remained, and a new correlation between the hypothalamus and cerebellum appeared. Thus, in addition to the previously described dopamine receptor restructuring, the restructuring of MR mRNA correlations reveals an additional mechanism for adaptation to the c-fos gene knockout.
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Affiliation(s)
- Jan Benes
- Institute of Physiology, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
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76
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Bohinc BN, Gesty-Palmer D. Arrestins in Bone. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 118:335-58. [DOI: 10.1016/b978-0-12-394440-5.00013-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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77
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Signalling Complexes: Protein-Protein Interactions and Lipid Rafts. Mol Pharmacol 2012. [DOI: 10.1002/9781118451908.ch11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Barwell J, Gingell JJ, Watkins HA, Archbold JK, Poyner DR, Hay DL. Calcitonin and calcitonin receptor-like receptors: common themes with family B GPCRs? Br J Pharmacol 2012; 166:51-65. [PMID: 21649645 DOI: 10.1111/j.1476-5381.2011.01525.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The calcitonin receptor (CTR) and calcitonin receptor-like receptor (CLR) are two of the 15 human family B (or Secretin-like) GPCRs. CTR and CLR are of considerable biological interest as their pharmacology is moulded by interactions with receptor activity-modifying proteins. They also have therapeutic relevance for many conditions, such as osteoporosis, diabetes, obesity, lymphatic insufficiency, migraine and cardiovascular disease. In light of recent advances in understanding ligand docking and receptor activation in both the family as a whole and in CLR and CTR specifically, this review reflects how applicable general family B GPCR themes are to these two idiosyncratic receptors. We review the main functional domains of the receptors; the N-terminal extracellular domain, the juxtamembrane domain and ligand interface, the transmembrane domain and the intracellular C-terminal domain. Structural and functional findings from the CLR and CTR along with other family B GPCRs are critically appraised to gain insight into how these domains may function. The ability for CTR and CLR to interact with receptor activity-modifying proteins adds another level of sophistication to these receptor systems but means careful consideration is needed when trying to apply generic GPCR principles. This review encapsulates current thinking in the realm of family B GPCR research by highlighting both conflicting and recurring themes and how such findings relate to two unusual but important receptors, CTR and CLR.
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Affiliation(s)
- James Barwell
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, UK
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Miller LJ, Dong M, Harikumar KG. Ligand binding and activation of the secretin receptor, a prototypic family B G protein-coupled receptor. Br J Pharmacol 2012; 166:18-26. [PMID: 21542831 DOI: 10.1111/j.1476-5381.2011.01463.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The secretin receptor is a prototypic member of family B G protein-coupled receptors that binds and responds to a linear 27-residue peptide natural ligand. The carboxyl-terminal region of this peptide assumes a helical conformation that occupies the peptide-binding cleft within the structurally complex disulphide-bonded amino-terminal domain of this receptor. The amino terminus of secretin is directed toward the core helical bundle domain of this receptor that seems to be structurally distinct from the analogous region of family A G protein-coupled receptors. This amino-terminal region of secretin is critical for its biological activity, to stimulate Gs coupling and the agonist-induced cAMP response. While the natural peptide ligand is known to span the two key receptor domains, with multiple residue-residue approximation constraints well established, the orientation of the receptor amino terminus relative to the receptor core helical bundle domain is still unclear. Fluorescence studies have established that the mid-region and carboxyl-terminal end of secretin are protected by the receptor peptide-binding cleft and the amino terminus of secretin is most exposed to the aqueous milieu as it is directed toward the receptor core, with the mid-region of the peptide becoming more exposed upon receptor activation. Like other family B peptide hormone receptors, the secretin receptor is constitutively present in a structurally specific homo-dimeric complex built around the lipid-exposed face of transmembrane segment four. This complex is important for facilitating G protein association and achieving the high affinity state of this receptor.
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Affiliation(s)
- Laurence J Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, USA.
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80
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Kuwasako K, Hay DL, Nagata S, Hikosaka T, Kitamura K, Kato J. The third extracellular loop of the human calcitonin receptor-like receptor is crucial for the activation of adrenomedullin signalling. Br J Pharmacol 2012; 166:137-50. [PMID: 22142144 DOI: 10.1111/j.1476-5381.2011.01803.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND AND PURPOSE The extracellular loops (ECLs) in Family A GPCRs are important for ligand binding and receptor activation, but little is known about the function of Family B GPCR ECLs, especially ECL3. Calcitonin receptor-like receptor (CLR), a Family B GPCR, functions as a calcitonin gene-related peptide (CGRP) and an adrenomedullin (AM) receptor in association with three receptor activity-modifying proteins (RAMPs). Here, we examined the function of the ECL3 of human CLR within the CGRP and AM receptors. EXPERIMENTAL APPROACH A CLR ECL3 chimera, in which the ECL3 of CLR was substituted with that of VPAC2 (a Family B GPCR that is unable to interact with RAMPs), and CLR ECL3 point mutants were constructed and transiently transfected into HEK-293 cells along with each RAMP. Cell-surface expression of each receptor complex was then measured by flow cytometry; [(125) I]-CGRP and [(125) I]-AM binding and intracellular cAMP accumulation were also measured. KEY RESULTS Co-expression of the CLR ECL3 chimera with RAMP2 or RAMP3 led to significant reductions in the induction of cAMP signalling by AM, but CGRP signalling was barely affected, despite normal cell-surface expression of the receptors and normal [(125) I]-AM binding. The chimera had significantly decreased AM, but not CGRP, responses in the presence of RAMP1. Not all CLR ECL3 mutants supported these findings. CONCLUSIONS AND IMPLICATIONS The human CLR ECL3 is crucial for AM-induced cAMP responses via three CLR/RAMP heterodimers, and activation of these heterodimers probably relies on AM-induced conformational changes. This study provides a clue to the molecular basis of the activation of RAMP-based Family B GPCRs.
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Affiliation(s)
- Kenji Kuwasako
- Frontier Science Research Center, University of Miyazaki, Miyazaki, Japan.
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81
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Poyner DR, Hay DL. Secretin family (Class B) G protein-coupled receptors - from molecular to clinical perspectives. Br J Pharmacol 2012; 166:1-3. [PMID: 22489621 DOI: 10.1111/j.1476-5381.2011.01810.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Family B G protein-coupled receptors represent an important but under-researched group of receptors. This edition of the British Journal of Pharmacology considers the roles and pharmacology of a number of these receptors. Whilst common themes emerge, it is clear that more work is needed to understand the details of each receptor in order to properly exploit them therapeutically.
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82
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Moore EL, Salvatore CA. Targeting a family B GPCR/RAMP receptor complex: CGRP receptor antagonists and migraine. Br J Pharmacol 2012; 166:66-78. [PMID: 21871019 DOI: 10.1111/j.1476-5381.2011.01633.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The clinical effectiveness of antagonizing the calcitonin gene-related peptide (CGRP) receptor for relief of migraine pain has been clearly demonstrated, but the road to the development of these small molecule antagonists has been daunting. The key hurdle that needed to be overcome was the CGRP receptor itself. The vast majority of the current antagonists recognize similar epitopes on the calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein 1 (RAMP1). RAMP1 is a relatively small, single, transmembrane-spanning protein and along with the G-protein-coupled receptor CLR comprise a functional CGRP receptor. The tri-helical extracellular domain of RAMP1 plays a key role in the high affinity binding of CGRP receptor antagonists and drives their species-selective pharmacology. Over the years, a significant amount of mutagenesis data has been generated to identify specific amino acids or regions within CLR and RAMP1 that are critical to antagonist binding and has directed attention to the CLR/RAMP1 extracellular domain (ECD) complex. Recently, the crystal structure of the CGRP receptor ECD has been elucidated and not only reinforces the early mutagenesis data, but provides critical insight into the molecular mechanism of CGRP receptor antagonism. This review will highlight the drug design hurdles that must be overcome to meet the desired potency, selectivity and pharmacokinetic profile while retaining drug-like properties. Although the development of these antagonists has proved challenging, blocking the CGRP receptor may one day represent a new way to manage migraine and offer hope to migraine sufferers.
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Affiliation(s)
- Eric L Moore
- Department of Pain & Migraine Research, Merck Research Laboratories, West Point, PA, USA.
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83
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Kenakin TP. Biased signalling and allosteric machines: new vistas and challenges for drug discovery. Br J Pharmacol 2012; 165:1659-1669. [PMID: 22023017 DOI: 10.1111/j.1476-5381.2011.01749.x] [Citation(s) in RCA: 179] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Seven transmembrane receptors (7TMRs) are nature's prototype allosteric proteins made to bind molecules at one location to subsequently change their shape to affect the binding of another molecule at another location. This paper attempts to describe the divergent 7TMR behaviours (i.e. third party allostery, receptor oligomerization, biased agonism) observed in pharmacology in terms of a homogeneous group of allosteric behaviours. By considering the bodies involved as a vector defined by a modulator, conduit and guest, these activities can all be described by a simple model of functional allostery made up of the Ehlert allosteric model and the Black/Leff operational model. It will be shown how this model yields parameters that can be used to characterize the activity of any ligand or protein producing effect through allosteric interaction with a 7TMR.
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Affiliation(s)
- Terry P Kenakin
- Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina, USA
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84
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Halim A, Hay DL. The role of glutamic acid 73 in adrenomedullin interactions with rodent AM2 receptors. Peptides 2012; 36:137-41. [PMID: 22546239 DOI: 10.1016/j.peptides.2012.04.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 04/13/2012] [Accepted: 04/13/2012] [Indexed: 11/22/2022]
Abstract
Adrenomedullin (AM) is a peptide, which is important for vascular development. There is much interest in the clinical potential of its receptors. The mode of AM binding to its receptors is poorly understood. Previous studies have identified amino acid Glu74, which is found in the receptor activity-modifying protein (RAMP3) subunit of the AM(2) receptor as important for high affinity AM interactions with this receptor. Its reciprocal residue in RAMP1 (Trp) impedes AM interactions in the closely related human calcitonin gene-related peptide (CGRP) receptor. The Glu is conserved in RAMP3 across species, supporting its role in contributing to AM binding. We mutated this residue in rat and mouse RAMP3 to Ala, Lys and Trp to determine its function in rodent AM(2) receptors. Only the Trp substitution in mouse RAMP3 produced a substantial reduction in AM potency. However, mutation of the Lys found in rat RAMP1 to Glu enhanced AM potency. Although Glu is highly conserved in RAMP3, this work suggests that it may only make a small or indirect contribution to AM interactions. Nevertheless, the equivalent amino acid in RAMP1 may serve to impair high affinity AM interactions.
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Affiliation(s)
- Angela Halim
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
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85
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Jusek G, Reim D, Tsujikawa K, Holzmann B. Deficiency of the CGRP receptor component RAMP1 attenuates immunosuppression during the early phase of septic peritonitis. Immunobiology 2012; 217:761-7. [PMID: 22656887 DOI: 10.1016/j.imbio.2012.04.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Accepted: 04/27/2012] [Indexed: 01/15/2023]
Abstract
The neuropeptide CGRP contributes to the control of excessive cytokine production in endotoxemia models. However, the function of CGRP in sepsis caused by infection with viable pathogens is unknown. Here, we show that mice deficient for the CGRP receptor component RAMP1 have an improved anti-bacterial defense during the early, but not late, phase of polymicrobial septic peritonitis. The protective effect of Ramp1-deficiency was associated with reduced levels of IL-10 in plasma and peritoneal lavage fluid. Consistent with these findings, CGRP markedly increased IL-10 production of peritoneal and bone marrow-derived macrophages in response to short term stimulation with LPS in vitro. In addition, the lack of an intact CGRP receptor resulted in an increased recruitment and activation of neutrophils and caused an enhanced release of defensin-α1 in the peritoneal cavity. Considered together, our results identify the neuropeptide CGRP as a crucial immunosuppressive mediator impairing host defense during the early, but not late, phase of septic peritonitis.
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Affiliation(s)
- Gabriela Jusek
- Department of Surgery, Technical University Munich, Ismaninger Strasse 22, 81675 Munich, Germany
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86
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Kuwasako K, Kitamura K, Nagata S, Nozaki N, Kato J. Characterization of the single transmembrane domain of human receptor activity-modifying protein 3 in adrenomedullin receptor internalization. Biochem Biophys Res Commun 2012; 420:582-7. [PMID: 22445753 DOI: 10.1016/j.bbrc.2012.03.037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 03/08/2012] [Indexed: 01/27/2023]
Abstract
Two receptor activity-modifying proteins (RAMP2 and RAMP3) enable calcitonin receptor-like receptor (CLR) to function as two heterodimeric receptors (CLR/RAMP2 and CLR/RAMP3) for adrenomedullin (AM), a potent cardiovascular protective peptide. Following AM stimulation, both receptors undergo rapid internalization through a clathrin-dependent pathway, after which CLR/RAMP3, but not CLR/RAMP2, can be recycled to the cell surface for resensitization. However, human (h)RAMP3 mediates CLR internalization much less efficiently than does hRAMP2. Therefore, the molecular basis of the single transmembrane domain (TMD) and the intracellular domain of hRAMP3 during AM receptor internalization was investigated by transiently transfecting various RAMP chimeras and mutants into HEK-293 cells stably expressing hCLR. Flow cytometric analysis revealed that substituting the RAMP3 TMD with that of RAMP2 markedly enhanced AM-induced internalization of CLR. However, this replacement did not enhance the cell surface expression of CLR, [(125)I]AM binding affinity or AM-induced cAMP response. More detailed analyses showed that substituting the Thr(130)-Val(131) sequence in the RAMP3 TMD with the corresponding sequence (Ile(157)-Pro(158)) from RAMP2 significantly enhanced AM-mediated CLR internalization. In contrast, substituting the RAMP3 target sequence with Ala(130)-Ala(131) did not significantly affect CLR internalization. Thus, the RAMP3 TMD participates in the negative regulation of CLR/RAMP3 internalization, and the aforementioned introduction of the Ile-Pro sequence into the RAMP3 TMD may be a strategy for promoting receptor internalization/resensitization.
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Affiliation(s)
- Kenji Kuwasako
- Frontier Science Research Center, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki, Miyazaki 889-1692, Japan.
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87
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Tang XL, Wang Y, Li DL, Luo J, Liu MY. Orphan G protein-coupled receptors (GPCRs): biological functions and potential drug targets. Acta Pharmacol Sin 2012; 33:363-71. [PMID: 22367282 DOI: 10.1038/aps.2011.210] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The superfamily of G protein-coupled receptors (GPCRs) includes at least 800 seven-transmembrane receptors that participate in diverse physiological and pathological functions. GPCRs are the most successful targets of modern medicine, and approximately 36% of marketed pharmaceuticals target human GPCRs. However, the endogenous ligands of more than 140 GPCRs remain unidentified, leaving the natural functions of those GPCRs in doubt. These are the so-called orphan GPCRs, a great source of drug targets. This review focuses on the signaling transduction pathways of the adhesion GPCR family, the LGR subfamily, and the PSGR subfamily, and their potential functions in immunology, development, and cancers. In this review, we present the current approaches and difficulties of orphan GPCR deorphanization and characterization.
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88
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Granholm S, Henning P, Lerner UH. Comparisons between the effects of calcitonin receptor-stimulating peptide and intermedin and other peptides in the calcitonin family on bone resorption and osteoclastogenesis. J Cell Biochem 2012; 112:3300-12. [PMID: 21748786 DOI: 10.1002/jcb.23256] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Calcitonin receptor-stimulating peptide (CRSP) and intermedin (IMD) are two recently discovered peptides in the calcitonin (CT) family of peptides. CRSP and IMD, similar to CT, calcitonin gene-related peptide (CGRP), and amylin (AMY), but in contrast to adrenomedullin (ADM), inhibited bone resorption in mouse calvarial bones. CRSP and IMD, similar to CT, CGRP, AMY, but in contrast to ADM, decreased formation of osteoclasts and number of pits in bone marrow macrophage cultures stimulated by M-CSF and RANKL, with no effect on the expression of a number of genes associated with osteoclast progenitor cell differentiation. CRSP and IMD inhibited osteoclastogenesis at a late stage but had no effect on DC-STAMP mRNA. IMD, similar to CGRP, AMY, and ADM stimulated cyclic AMP formation in M-CSF expanded osteoclast progenitor cells lacking CT receptors (CTRs). RANKL induced CTRs and a cyclic AMP response also to CT and CRSP, and increased the cyclic AMP response to CGRP, AMY, and IMD but decreased the response to ADM. Our data demonstrates that CRSP and IMD share several functional properties of peptides in the CT family of peptides, including inhibition of bone resorption and osteoclast formation. The data also show that the reason why ADM does not inhibit osteoclast activity or formation is related to the fact that RANKL decreases ADM receptor signaling through the adenylate cyclase-cyclic AMP pathway. Finally, the findings indicate that activation by CGRP, AMY, and IMD may include activation of both CT and CT receptor-like receptors.
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Affiliation(s)
- Susanne Granholm
- Department of Molecular Periodontology, Umeå University, S-901 87 Umeå, Sweden
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89
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Kusano S, Kukimoto-Niino M, Hino N, Ohsawa N, Okuda KI, Sakamoto K, Shirouzu M, Shindo T, Yokoyama S. Structural basis for extracellular interactions between calcitonin receptor-like receptor and receptor activity-modifying protein 2 for adrenomedullin-specific binding. Protein Sci 2012; 21:199-210. [PMID: 22102369 PMCID: PMC3324764 DOI: 10.1002/pro.2003] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 11/10/2011] [Indexed: 11/06/2022]
Abstract
The calcitonin receptor-like receptor (CRLR), a class B GPCR, forms a heterodimer with receptor activity-modifying protein 2 (RAMP2), and serves as the adrenomedullin (AM) receptor to control neovascularization, while CRLR and RAMP1 form the calcitonin gene-related peptide (CGRP) receptor. Here, we report the crystal structures of the RAMP2 extracellular domain alone and in the complex with the CRLR extracellular domain. The CRLR-RAMP2 complex exhibits several intermolecular interactions that were not observed in the previously reported CRLR-RAMP1 complex, and thus the shape of the putative ligand-binding pocket of CRLR-RAMP2 is distinct from that of CRLR-RAMP1. The CRLR-RAMP2 interactions were confirmed for the full-length proteins on the cell surface by site-specific photo-crosslinking. Mutagenesis revealed that AM binding requires RAMP2 residues that are not conserved in RAMP1. Therefore, the differences in both the shapes and the key residues of the binding pocket are essential for the ligand specificity.
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Affiliation(s)
- Seisuke Kusano
- RIKEN Systems and Structural Biology Center1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Mutsuko Kukimoto-Niino
- RIKEN Systems and Structural Biology Center1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Nobumasa Hino
- RIKEN Systems and Structural Biology Center1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Noboru Ohsawa
- RIKEN Systems and Structural Biology Center1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Ken-ichi Okuda
- RIKEN Systems and Structural Biology Center1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Kensaku Sakamoto
- RIKEN Systems and Structural Biology Center1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Mikako Shirouzu
- RIKEN Systems and Structural Biology Center1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Takayuki Shindo
- Department of Organ Regeneration, Graduate School of Medicine, Shinshu UniversityMatsumoto, Nagano 390-8621, Japan
| | - Shigeyuki Yokoyama
- RIKEN Systems and Structural Biology Center1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
- Laboratory of Structural Biology, Department of Biophysics and Biochemistry, Graduate School of Science, The University of TokyoBunkyo-ku, Tokyo 113-0033, Japan
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90
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Nag K, Sultana N, Hirose S. Calcitonin receptor-like receptor (CLR) influences posttranslational events of receptor activity-modifying proteins (RAMPs). Biochem Biophys Res Commun 2012; 418:824-9. [DOI: 10.1016/j.bbrc.2012.01.116] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2012] [Accepted: 01/24/2012] [Indexed: 11/29/2022]
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91
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Castro FV, McGinn OJ, Krishnan S, Marinov G, Li J, Rutkowski AJ, Elkord E, Burt DJ, Holland M, Vaghjiani R, Gallego A, Saha V, Stern PL. 5T4 oncofetal antigen is expressed in high risk of relapse childhood pre-B acute lymphoblastic leukemia and is associated with a more invasive and chemotactic phenotype. Leukemia 2012; 26:1487-98. [PMID: 22266911 PMCID: PMC3378689 DOI: 10.1038/leu.2012.18] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Although the overall prognosis in childhood acute lymphoblastic leukemia (ALL) is good, outcome after relapse is poor. Recurrence is frequently characterized by the occurrence of disease at extramedullary sites, such as the central nervous system and testes. Subpopulations of blasts able to migrate to such areas may have a survival advantage and give rise to disease recurrence. Gene expression profiling of 85 diagnostic pre-B-ALL bone marrow samples revealed higher 5T4 oncofetal antigen transcript levels in cytogenetic high-risk subgroups of patients (P<0.001). Flow cytometric analysis determined that bone marrow from relapse patients have a significantly higher percentage of 5T4-positive leukemic blasts than healthy donors (P=0.005). The high-risk Sup-B15 pre-B-ALL line showed heterogeneity in 5T4 expression, and the derived, 5T4(+) (Sup5T4) and 5T4(-) (Sup) subline cells, displayed differential spread to the omentum and ovaries following intraperitoneal inoculation of immunocompromised mice. Consistent with this, Sup5T4 compared with Sup cells show increased invasion in vitro concordant with increased LFA-1 and VLA-4 integrin expression, adhesion to extracellular matrix and secretion of matrix metalloproteases (MMP-2/-9). We also show that 5T4-positive Sup-B15 cells are susceptible to 5T4-specific superantigen antibody-dependent cellular toxicity providing support for targeted immunotherapy in high-risk pre-B-ALL.
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Affiliation(s)
- F V Castro
- Cancer Research UK Immunology Group, Paterson Institute for Cancer Research, University of Manchester, Manchester, UK
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92
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Jacob A, Wu R, Wang P. Regulation of RAMP expression in diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 744:87-103. [PMID: 22434110 DOI: 10.1007/978-1-4614-2364-5_8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Receptor-activity modifying proteins (RAMPs) belong to a single family of transmembrane proteins. RAMPs determine ligand specificity of G-protein coupled receptors; calcitonin receptor and the calcitonin-receptor like receptor (CLR). To date, three members of RAMP family (RAMP-1, -2, -3) have been identified. The co-expression of RAMP-1 with CLR constitutes the calcitonin gene related peptide receptor whereas the association of the RAMP-2 or RAMP-3 with CLR forms the adrenomedullin (AM) receptor. Alterations in signaling and subcellular distribution of G-protein coupled receptors can be responsible for the regulation of many disease conditions. These changes may be mediated by the different isoforms of RAMPs associated with such receptors. In this chapter, we describe the differential responses associated with upregulation of RAMPs in disease conditions. For instance, the upregulation of all three RAMP isoforms contributes to the cardioprotective effects of the CLR/RAMP ligands. On the other hand, strong evidence exists for the involvement of AM in various cancers and that its action is mediated by the upregulation of RAMP isoforms, RAMP-2 and -3. Though limited, a few studies have been reported on the differential response associated with the upregulation of RAMP in other disease conditions such as sepsis, liver cirrhosis, glomerulonephritis, Type 1 diabetes and Parkinson's disease. Thus, the regulation of RAMP expression is involved in the pathophysiology associated with various diseases.
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Affiliation(s)
- Asha Jacob
- The Feinstein Institute of Medical Research, Manhasset, NY, USA
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93
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Sexton PM, Poyner DR, Simms J, Christopoulos A, Hay DL. RAMPs as drug targets. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 744:61-74. [PMID: 22434108 DOI: 10.1007/978-1-4614-2364-5_6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
The receptor activity-modifying protein (RAMP) family of membrane proteins regulates G protein-coupled receptor (GPCR) function in several ways. RAMPs can alter their pharmacology and signalling as well as the trafficking of these receptors to and from the cell surface. Accordingly, RAMPs may be exploited as drug targets, offering new opportunities for regulating the function of therapeutically relevant RAMP-interacting GPCRs. For example, several small molecule antagonists of RAMP1/ calcitonin receptor-like receptor complexes, which block the actions of the neuropeptide calcitonin gene-related peptide are in development for the treatment of migraine headache.
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Affiliation(s)
- Patrick M Sexton
- Department of Pharmacology, Monash University, Victoria, Australia
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94
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Kadmiel M, Fritz-Six KL, Caron KM. Understanding RAMPs through genetically engineered mouse models. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 744:49-60. [PMID: 22434107 DOI: 10.1007/978-1-4614-2364-5_5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The family of Receptor Activity Modifying Proteins (RAMPs) consists of three members, RAMP1, 2 and 3, which are each encoded by a separate gene and have diverse spatiotemporal expression patterns. Biochemical and pharmacological studies in cultured cells have shown that RAMPs can modulate several aspects of G receptor (GPCR) signaling, including receptor trafficking, ligand binding affinity, second messenger signaling and receptor desensitization. Moreover, these studies have shown that RAMPs can interact with several GPCRs other than the canonical calcitonin receptor-like receptor (CLR), with which they were first identified. Given these expanding roles for RAMPs, it becomes interesting to question how these biochemical and pharmacological properties bear significance in normal or disease physiology. To this end, several gene targeted knockout and transgenic models have been generated and characterized in recent years. Fortunately, they have each supported important roles for RAMPs during embryonic development and adulthood. This chapter provides a comprehensive overview of the most recent findings from gene targeted knockout mouse models and transgenic over-expression models, and gives special consideration to how comparative phenotyping approaches and conditional deletion strategies can be highly beneficial. In the future, these genetically engineered mouse models will provide both insights and tools for the exploitation of RAMP-based therapies for the treatment of human diseases.
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Affiliation(s)
- Mahita Kadmiel
- Department of Cell and Molecular Physiology, The University of North Carolina, Chapel Hill, NC, USA
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95
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Holzmann B. Modulation of immune responses by the neuropeptide CGRP. Amino Acids 2011; 45:1-7. [PMID: 22113645 DOI: 10.1007/s00726-011-1161-2] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 11/14/2011] [Indexed: 01/15/2023]
Abstract
The peripheral nervous system is connected with lymphoid organs through sensory nerves that mediate pain reflexes and may influence immune responses through the release of neuropeptides such as calcitonin gene-related peptide (CGRP). Local and systemic levels of CGRP increase rapidly during inflammatory responses. CGRP inhibits effector functions of various immune cells and dampens inflammation by distinct pathways involving the amplification of IL-10 production and/or the induction of the transcriptional repressor inducible cAMP early repressor (ICER). Thus, available evidence suggests that, in neuro-immunological interactions, CGRP mediates a potent peptidergic anti-inflammatory pathway.
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Affiliation(s)
- Bernhard Holzmann
- Department of Surgery, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 München, Germany.
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Barrick CJ, Lenhart PM, Dackor RT, Nagle E, Caron KM. Loss of receptor activity-modifying protein 3 exacerbates cardiac hypertrophy and transition to heart failure in a sex-dependent manner. J Mol Cell Cardiol 2011; 52:165-74. [PMID: 22100352 DOI: 10.1016/j.yjmcc.2011.10.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Revised: 10/18/2011] [Accepted: 10/24/2011] [Indexed: 10/15/2022]
Abstract
Sex differences exist in the hypertrophic response, cardiac remodeling, and transition to heart failure of hypertensive patients, and while some of these differences are likely influenced by estrogen, the genetic pathways downstream of estrogen that impact on cardioprotection have yet to be fully elucidated. We have previously shown that the cardioprotective effects of adrenomedullin (AM), an emerging clinical biomarker for cardiovascular disease severity, vary with sex in mouse models. AM signaling during cardiovascular stress is strongly modulated by receptor activity-modifying protein 3 (RAMP3) via its interaction with the G protein-coupled receptor calcitonin receptor-like receptor (CLR). Like AM, RAMP3 expression is potently regulated by estrogen, and so we sought to determine the consequences of genetic Ramp3 loss on cardiac adaptation to chronic hypertension, with a particular focus on characterizing potential sex differences. We generated and bred RAMP3(-/-) mice to RenTgMK mice that consistently display severe angiotensin II-mediated CV disease and compared CV disease progression in RenTgMK to that of RenTgMK:RAMP3(-/-) offspring. As expected, RAMP3 gene expression was higher in cardiovascular tissues of RenTgMK mice and more strongly up-regulated in female RenTgMK mice relative to wildtype controls. RAMP3 loss did not affect the development of hypertension or the presence and severity of perivascular and interstitial fibrosis in the left ventricle (LV). However, echocardiography revealed that while RenTgMK mice developed concentric cardiac hypertrophy with sustained systolic function, male RenTgMK:RAMP3(-/-) mice showed evidence of LV chamber dilatation and depressed systolic function, suggestive of cardiac decompensation. Consistent with these measures of heart failure, male RenTgMK:RAMP3(-/-) mice had increased cardiac apoptosis and elevated activation of Akt. These phenotypes were not present in female RenTgMK:RAMP3(-/-) mice. Collectively, these data demonstrate a sex-dependant, cardioprotective role of RAMP3 in the setting of chronic hypertension.
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Affiliation(s)
- Cordelia J Barrick
- Department of Cell & Molecular Physiology, The University of North Carolina, Chapel Hill, NC 27599, USA
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97
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Liang L, Sebag JA, Eagelston L, Serasinghe MN, Veo K, Reinick C, Angleson J, Hinkle PM, Dores RM. Functional expression of frog and rainbow trout melanocortin 2 receptors using heterologous MRAP1s. Gen Comp Endocrinol 2011; 174:5-14. [PMID: 21846469 DOI: 10.1016/j.ygcen.2011.07.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 07/21/2011] [Accepted: 07/21/2011] [Indexed: 11/27/2022]
Abstract
Analysis of the functional expression of the melanocortin 2 receptor (MC2R) from a rather broad spectrum of vertebrates indicates that MC2R is exclusively selective for the ligand, ACTH, and the melanocortin receptor accessory protein 1 (MRAP1) is required for high affinity ACTH binding and activation of MC2R. A phylogenetic analysis of MRAP1 suggested that tetrapod sequences and bony fish sequences may represent two distinct trends in the evolution of the mrap1 gene. To test this hypothesis, a frog (Xenopus tropicalis) MC2R was expressed in CHO cells either in the presence of a tetrapod (mouse) MRAP1 or a bony fish (zebrafish) MRAP1. The response of frog MC2R to different concentrations of human ACTH(1-24) was more robust in the presence of mouse MRAP1 than in the presence of zebrafish MRAP1. Conversely, the cAMP response mediated by the rainbow trout (Oncorhynchus mykiss) MC2R was almost twofold higher and occurred at 1000-fold lower ACTH concentration in the presence of zebrafish MRAP1 than in the presence of mouse MRAP1. Collectively, these experiments raise the possibility that at least two distinct trends have emerged in the co-evolution of MC2R/MRAP1 interactions during the radiation of the vertebrates.
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Affiliation(s)
- Liang Liang
- Department of Biological Sciences, University of Denver, Denver, CO 80210, USA
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98
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Structural insights into RAMP modification of secretin family G protein-coupled receptors: implications for drug development. Trends Pharmacol Sci 2011; 32:591-600. [DOI: 10.1016/j.tips.2011.05.007] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 05/25/2011] [Accepted: 05/26/2011] [Indexed: 11/18/2022]
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Kuwasako K, Kitamura K, Nagata S, Hikosaka T, Takei Y, Kato J. Shared and separate functions of the RAMP-based adrenomedullin receptors. Peptides 2011; 32:1540-50. [PMID: 21645567 DOI: 10.1016/j.peptides.2011.05.022] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 05/20/2011] [Accepted: 05/20/2011] [Indexed: 11/25/2022]
Abstract
Adrenomedullin (AM) is a novel hypotensive peptide that exerts a variety of strongly protective effects against multiorgan damage. AM-specific receptors were first identified as heterodimers composed of calcitonin-receptor-like receptor (CLR), a G protein coupled receptor, and one of two receptor activity-modifying proteins (RAMP2 or RAMP3), which are accessory proteins containing a single transmembrane domain. RAMPs are required for the surface delivery of CLR and the determination of its phenotype. CLR/RAMP2 (AM₁ receptor) is more highly AM-specific than CLR/RAMP3 (AM₂ receptor). Although there have been no reports showing differences in intracellular signaling via the two AM receptors, in vitro studies have shed light on their distinct trafficking and functionality. In addition, the tissue distributions of RAMP2 and RAMP3 differ, and their gene expression is differentially altered under pathophysiological conditions, which is suggestive of the separate roles played by AM₁ and AM₂ receptors in vivo. Both AM and the AM₁ receptor, but not the AM₂ receptor, are crucial for the development of the fetal cardiovascular system and are able to effectively protect against various vascular diseases. However, AM₂ receptors reportedly play an important role in maintaining a normal body weight in old age and may be involved in immune function. In this review article, we focus on the shared and separate functions of the AM receptor subtypes and also discuss the potential for related drug discovery. In addition, we mention their possible function as receptors for AM2 (or intermedin), an AM-related peptide whose biological functions are similar to those of AM.
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Affiliation(s)
- Kenji Kuwasako
- Frontier Science Research Center, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki, Miyazaki 889-1692, Japan.
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100
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Zhang Z, Liu X, Morgan DA, Kuburas A, Thedens DR, Russo AF, Rahmouni K. Neuronal receptor activity-modifying protein 1 promotes energy expenditure in mice. Diabetes 2011; 60:1063-71. [PMID: 21357463 PMCID: PMC3064080 DOI: 10.2337/db10-0692] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Receptor activity-modifying proteins (RAMPs) 1, 2, and 3 are unusual accessory proteins that dictate the binding specificity of two G protein-coupled receptors involved in energy homeostasis: calcitonin gene-related peptide (CGRP) and amylin receptors. These proteins are expressed throughout the central nervous system (CNS), including in the brain regions involved in the regulation of energy homeostasis, but the significance of CNS RAMPs in the control of energy balance remains unknown. RESEARCH DESIGN AND METHODS To examine the functional significance of modulating neuronal RAMP1, we assessed the effect of overexpressing human RAMP1 (hRAMP1) in the CNS on body energy balance. RESULTS Nestin/hRAMP1 transgenic mice have a remarkably decreased body weight associated with reduced fat mass and circulating leptin levels. The transgenic mice exhibited higher energy expenditure as indicated by increased oxygen consumption, body temperature, and sympathetic tone subserving brown adipose tissue (BAT). Consistent with this, the nestin/hRAMP1 transgenic mice had elevated BAT mRNA levels of peroxisome proliferator-activated receptor γ coactivator 1α and uncoupling protein 1 and 3, and these changes can be reversed by chronic blockade of sympathetic nervous system signaling. Furthermore, metabolic response to amylin was enhanced in the nestin/hRAMP1 mice whereas the response to CGRP was blunted, possibly the result of higher expression of CGRP in the CNS. CONCLUSIONS These data demonstrate that CNS RAMP1 plays a pivotal role in the regulation of energy homeostasis by promoting energy expenditure.
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Affiliation(s)
- Zhongming Zhang
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Xuebo Liu
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Donald A. Morgan
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Adisa Kuburas
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Daniel R. Thedens
- Department of Radiology, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Andrew F. Russo
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Kamal Rahmouni
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa
- Corresponding author: Kamal Rahmouni,
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