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Cong Z, Liang YL, Zhou Q, Darbalaei S, Zhao F, Feng W, Zhao L, Xu HE, Yang D, Wang MW. Structural perspective of class B1 GPCR signaling. Trends Pharmacol Sci 2022; 43:321-334. [DOI: 10.1016/j.tips.2022.01.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 01/01/2022] [Accepted: 01/03/2022] [Indexed: 12/12/2022]
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2
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Fodor J, Hull JJ, Köblös G, Jacquin-Joly E, Szlanka T, Fónagy A. Identification and functional characterization of the pheromone biosynthesis activating neuropeptide receptor isoforms from Mamestra brassicae. Gen Comp Endocrinol 2018; 258:60-69. [PMID: 28579335 DOI: 10.1016/j.ygcen.2017.05.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 05/26/2017] [Accepted: 05/31/2017] [Indexed: 11/19/2022]
Abstract
In most moth species, including Mamestra brassicae, pheromone biosynthesis activating neuropeptide (PBAN) regulates pheromone production. Generally, PBAN acts directly on the pheromone gland (PG) cells via its specific G protein-coupled receptor (i.e. PBANR) with Ca2+ as a second messenger. In this study, we identified cDNAs encoding three variants (A, B and C) of the M. brassicae PBANR (Mambr-PBANR). The full-length coding sequences were transiently expressed in cultured Trichoplusia ni cells and Sf9 cells for functional characterization. All three isoforms dose-dependently mobilized extracellular Ca2+ in response to PBAN analogs with Mambr-PBANR-C exhibiting the greatest sensitivity. Fluorescent confocal microscopy imaging studies demonstrated binding of a rhodamine red-labeled ligand (RR10CPBAN) to all three Mambr-PBANR isoforms. RR10CPBAN binding did not trigger ligand-induced internalization in cells expressing PBANR-A, but did in cells expressing the PBANR-B and -C isoforms. Furthermore, activation of the PBANR-B and -C isoforms with the 18 amino acid Mambr-pheromonotropin resulted in co-localization with a Drosophila melanogaster arrestin homolog (Kurtz), whereas stimulation with an unrelated peptide had no effect. PCR-based profiling of the three transcripts revealed a basal level of expression throughout development with a dramatic increase in PG transcripts from the day of adult emergence with PBANR-C being the most abundant.
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Affiliation(s)
- József Fodor
- Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, H-1022 Budapest, Hungary
| | - J Joe Hull
- Agricultural Research Service, United States Department of Agriculture, Arid Land Agricultural Research Center, Maricopa, AZ, USA
| | - Gabriella Köblös
- Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, H-1022 Budapest, Hungary.
| | - Emmanuelle Jacquin-Joly
- INRA iEES-Paris, Institute of Ecology and Environmental Sciences, Route de Saint-Cyr, Cedex 78026 Versailles, France
| | - Tamás Szlanka
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, H-6726 Szeged, Hungary
| | - Adrien Fónagy
- Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, H-1022 Budapest, Hungary
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3
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Hay DL, Walker CS. CGRP and its receptors. Headache 2017; 57:625-636. [PMID: 28233915 DOI: 10.1111/head.13064] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Revised: 01/26/2017] [Accepted: 02/01/2017] [Indexed: 02/01/2023]
Abstract
The calcitonin gene-related peptide (CGRP) neuropeptide system is an important but still evolving target for migraine. A fundamental consideration for all of the current drugs in clinical trials and for ongoing development in this area is the identity, expression pattern, and function of CGRP receptors because this knowledge informs safety and efficacy considerations. In recent years, only the calcitonin receptor-like receptor/receptor activity-modifying protein 1 (RAMP1) complex, known as the CGRP receptor, has generally been considered relevant. However, CGRP is capable of activating multiple receptors and could have more than one endogenous receptor. The recent identification of the CGRP-responsive calcitonin receptor/RAMP1 complex (AMY1 receptor - amylin subtype 1 receptor) in the trigeminovascular system warrants a deeper consideration of the molecular identity of CGRP receptor(s) involved in the pathophysiology, and thus potential treatment of migraine. This perspective considers some of the issues and implications.
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Affiliation(s)
- Debbie L Hay
- School of Biological Sciences, The University of Auckland, Auckland, New Zealand
| | - Christopher S Walker
- School of Biological Sciences, The University of Auckland, Auckland, New Zealand
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Lin TY, Huang WL, Lee WY, Luo CW. Identifying a Neuromedin U Receptor 2 Splice Variant and Determining Its Roles in the Regulation of Signaling and Tumorigenesis In Vitro. PLoS One 2015; 10:e0136836. [PMID: 26317338 PMCID: PMC4552561 DOI: 10.1371/journal.pone.0136836] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 08/10/2015] [Indexed: 11/18/2022] Open
Abstract
Neuromedin U (NMU) activates two G protein-coupled receptors, NMUR1 and NMUR2; this signaling not only controls many physiological responses but also promotes tumorigenesis in diverse tissues. We recently identified a novel truncated NMUR2 derived by alternative splicing, namely NMUR2S, from human ovarian cancer cDNA. Sequence analysis, cell surface ELISA and immunocytochemical staining using 293T cells indicated that NMUR2S can be expressed well on the cell surface as a six-transmembrane protein. Receptor pull-down and fluorescent resonance energy transfer assays demonstrated that NMUR1, NMUR2 and this newly discovered NMUR2S can not only form homomeric complexes but also heteromeric complexes with each other. Although not activated by NMU itself, functional assay in combination with receptor quantification and radio-ligand binding in 293T cells indicated that NMUR2S does not alter the translocation and stability of NMUR1 or NMUR2, but rather effectively dampens their signaling by blocking their NMU binding capability through receptor heterodimerization. We further demonstrated that NMU signaling is significantly up-regulated in human ovarian cancers, whereas expression of NMUR2S can block endogenous NMU signaling and further lead to suppression of proliferation in SKOV-3 ovarian cancer cells. In contrast, in monocytic THP-1 cells that express comparable levels of NMUR1 and NMUR2S, depletion of NMUR2S restored both the signaling and effect of NMU. Thus, these results not only reveal the presence of previously uncharacterized heteromeric relationships among NMU receptors but also provide NMUR2S as a potential therapeutic target for the future treatment of NMU signaling-mediated cancers.
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Affiliation(s)
- Ting-Yu Lin
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Wei-Lin Huang
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Wei-Yu Lee
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Ching-Wei Luo
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan
- * E-mail:
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Slominski AT, Zmijewski MA, Zbytek B, Tobin DJ, Theoharides TC, Rivier J. Key role of CRF in the skin stress response system. Endocr Rev 2013; 34:827-84. [PMID: 23939821 PMCID: PMC3857130 DOI: 10.1210/er.2012-1092] [Citation(s) in RCA: 303] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 08/02/2013] [Indexed: 02/08/2023]
Abstract
The discovery of corticotropin-releasing factor (CRF) or CRH defining the upper regulatory arm of the hypothalamic-pituitary-adrenal (HPA) axis, along with the identification of the corresponding receptors (CRFRs 1 and 2), represents a milestone in our understanding of central mechanisms regulating body and local homeostasis. We focused on the CRF-led signaling systems in the skin and offer a model for regulation of peripheral homeostasis based on the interaction of CRF and the structurally related urocortins with corresponding receptors and the resulting direct or indirect phenotypic effects that include regulation of epidermal barrier function, skin immune, pigmentary, adnexal, and dermal functions necessary to maintain local and systemic homeostasis. The regulatory modes of action include the classical CRF-led cutaneous equivalent of the central HPA axis, the expression and function of CRF and related peptides, and the stimulation of pro-opiomelanocortin peptides or cytokines. The key regulatory role is assigned to the CRFR-1α receptor, with other isoforms having modulatory effects. CRF can be released from sensory nerves and immune cells in response to emotional and environmental stressors. The expression sequence of peptides includes urocortin/CRF→pro-opiomelanocortin→ACTH, MSH, and β-endorphin. Expression of these peptides and of CRFR-1α is environmentally regulated, and their dysfunction can lead to skin and systemic diseases. Environmentally stressed skin can activate both the central and local HPA axis through either sensory nerves or humoral factors to turn on homeostatic responses counteracting cutaneous and systemic environmental damage. CRF and CRFR-1 may constitute novel targets through the use of specific agonists or antagonists, especially for therapy of skin diseases that worsen with stress, such as atopic dermatitis and psoriasis.
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Affiliation(s)
- Andrzej T Slominski
- MD, PhD, Department of Pathology and Laboratory Medicine, University of Tennessee Health Science Center; 930 Madison Avenue, Suite 500, Memphis, Tennessee 38163.
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Durán-Prado M, Gahete MD, Delgado-Niebla E, Martínez-Fuentes AJ, Vázquez-Martínez R, García-Navarro S, Gracia-Navarro F, Malagon MM, Luque RM, Castaño JP. Truncated variants of pig somatostatin receptor subtype 5 (sst5) act as dominant-negative modulators for sst2-mediated signaling. Am J Physiol Endocrinol Metab 2012; 303:E1325-34. [PMID: 23032684 DOI: 10.1152/ajpendo.00445.2012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Somatostatin (SST) and its related peptide cortistatin (CORT) exert their multiple actions through binding to the SST receptor (sst) family, generally considered to comprise five G protein-coupled receptors with seven transmembrane domains (TMD), named sst1-sst5, plus a splice sst2B variant. However, we recently discovered that human and rodent sst5 gene expression also generates, through noncanonical alternative splicing, novel truncated albeit functional sst5 variants with less than seven TMD. Here, we cloned and characterized for the first time the porcine wild-type sst5 (psst5, full-length) and identified two novel truncated psst5 variants with six and three TMD, thus termed psst5TMD6 and psst5TMD3, respectively. In line with that observed in human and rodent truncated sst5 variants, psst5TMD6 and psst5TMD3 are functional (e.g., activate calcium signaling), selectively respond to SST and CORT, respectively, and exhibit specific tissue expression profiles that differ from full-length psst5 and often overlaps with psst2 expression. Moreover, fluorescence resonance energy transfer analysis shows that psst5 truncated variants physically interact with psst2, thereby altering their localization at the plasma membrane and specifically disrupting the cellular response to SST and/or CORT. These results represent the first characterization of a key porcine SST receptor, psst5, and, together with our previous results, provide strong evidence that alternative splicing-derived, truncated sst5 variants with distinct functional capacities exist in the mammalian lineage, where they can act as dominant-negative receptors, by interacting directly with long, seven TMD variants, potentially contributing to modulate normal and pathological SST and CORT signaling.
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Affiliation(s)
- Mario Durán-Prado
- Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Reina Sofía University Hospital, Instituto Maimónides de Investigación Biomédica de Córdoba, and CIBER Fisiopatología de la Obesidad y Nutrición, Córdoba, Spain
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Wise H. The roles played by highly truncated splice variants of G protein-coupled receptors. J Mol Signal 2012; 7:13. [PMID: 22938630 PMCID: PMC3477067 DOI: 10.1186/1750-2187-7-13] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Accepted: 07/29/2012] [Indexed: 01/08/2023] Open
Abstract
Alternative splicing of G protein-coupled receptor (GPCR) genes greatly increases the total number of receptor isoforms which may be expressed in a cell-dependent and time-dependent manner. This increased diversity of cell signaling options caused by the generation of splice variants is further enhanced by receptor dimerization. When alternative splicing generates highly truncated GPCRs with less than seven transmembrane (TM) domains, the predominant effect in vitro is that of a dominant-negative mutation associated with the retention of the wild-type receptor in the endoplasmic reticulum (ER). For constitutively active (agonist-independent) GPCRs, their attenuated expression on the cell surface, and consequent decreased basal activity due to the dominant-negative effect of truncated splice variants, has pathological consequences. Truncated splice variants may conversely offer protection from disease when expression of co-receptors for binding of infectious agents to cells is attenuated due to ER retention of the wild-type co-receptor. In this review, we will see that GPCRs retained in the ER can still be functionally active but also that highly truncated GPCRs may also be functionally active. Although rare, some truncated splice variants still bind ligand and activate cell signaling responses. More importantly, by forming heterodimers with full-length GPCRs, some truncated splice variants also provide opportunities to generate receptor complexes with unique pharmacological properties. So, instead of assuming that highly truncated GPCRs are associated with faulty transcription processes, it is time to reassess their potential benefit to the host organism.
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Affiliation(s)
- Helen Wise
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, SAR, China.
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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: 3.8] [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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Wookey PJ, McLean CA, Hwang P, Furness SGB, Nguyen S, Kourakis A, Hare DL, Rosenfeld JV. The expression of calcitonin receptor detected in malignant cells of the brain tumour glioblastoma multiforme and functional properties in the cell line A172. Histopathology 2012; 60:895-910. [DOI: 10.1111/j.1365-2559.2011.04146.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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10
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Lee JM, Hull JJ, Kawai T, Goto C, Kurihara M, Tanokura M, Nagata K, Nagasawa H, Matsumoto S. Re-Evaluation of the PBAN Receptor Molecule: Characterization of PBANR Variants Expressed in the Pheromone Glands of Moths. Front Endocrinol (Lausanne) 2012; 3:6. [PMID: 22654850 PMCID: PMC3356081 DOI: 10.3389/fendo.2012.00006] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Accepted: 01/09/2012] [Indexed: 01/14/2023] Open
Abstract
Sex pheromone production in most moths is initiated following pheromone biosynthesis activating neuropeptide receptor (PBANR) activation. PBANR was initially cloned from pheromone glands (PGs) of Helicoverpa zea and Bombyx mori. The B. mori PBANR is characterized by a relatively long C-terminus that is essential for ligand-induced internalization, whereas the H. zea PBANR has a shorter C-terminus that lacks features present in the B. mori PBANR critical for internalization. Multiple PBANRs have been reported to be concurrently expressed in the larval CNS of Heliothis virescens. In the current study, we sought to examine the prevalence of multiple PBANRs in the PGs of three moths and to ascertain their potential functional relevance. Multiple PBANR variants (As, A, B, and C) were cloned from the PGs of all species examined with PBANR-C the most highly expressed. Alternative splicing of the C-terminal coding sequence of the PBAN gene gives rise to the variants, which are distinguishable only by the length and composition of their respective C-terminal tails. Transient expression of fluorescent PBANR chimeras in insect cells revealed that PBANR-B and PBANR-C localized exclusively to the cell surface while PBANR-As and PBANR-A exhibited varying degrees of cytosolic localization. Similarly, only the PBANR-B and PBANR-C variants underwent ligand-induced internalization. Taken together, our results suggest that PBANR-C is the principal receptor molecule involved in PBAN signaling regardless of moth species. The high GC content of the C-terminal coding sequence in the B and C variants, which makes amplification using conventional polymerases difficult, likely accounts for previous "preferential" amplification of PBANR-A like receptors from other species.
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Affiliation(s)
- Jae Min Lee
- Molecular Entomology Laboratory, RIKEN Advanced Science InstituteWako, Japan
| | - J. Joe Hull
- Agricultural Research Service, United States Department of Agriculture, Arid Land Agricultural Research CenterMaricopa, AZ, USA
- *Correspondence: J. Joe Hull, Agricultural Research Service, United States Department of Agriculture, Arid Land Agricultural Research Center, 21881 N Cardon Lane, Maricopa, AZ 85138, USA. e-mail: ; Shogo Matsumoto, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan. e-mail:
| | - Takeshi Kawai
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of TokyoTokyo, Japan
| | - Chie Goto
- Agricultural Research Center, National Agriculture and Food Research OrganizationTsukuba, Japan
| | - Masaaki Kurihara
- Molecular Entomology Laboratory, RIKEN Advanced Science InstituteWako, Japan
| | - Masaru Tanokura
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of TokyoTokyo, Japan
| | - Koji Nagata
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of TokyoTokyo, Japan
| | - Hiromichi Nagasawa
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of TokyoTokyo, Japan
| | - Shogo Matsumoto
- Molecular Entomology Laboratory, RIKEN Advanced Science InstituteWako, Japan
- *Correspondence: J. Joe Hull, Agricultural Research Service, United States Department of Agriculture, Arid Land Agricultural Research Center, 21881 N Cardon Lane, Maricopa, AZ 85138, USA. e-mail: ; Shogo Matsumoto, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan. e-mail:
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Córdoba-Chacón J, Gahete MD, Durán-Prado M, Luque RM, Castaño JP. Truncated somatostatin receptors as new players in somatostatin-cortistatin pathophysiology. Ann N Y Acad Sci 2011; 1220:6-15. [PMID: 21388399 DOI: 10.1111/j.1749-6632.2011.05985.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Somatostatin (SST) and cortistatin (CORT) act through a family of seven transmembrane domain (TMD) receptors (sst1-5) to govern multiple functions, from growth hormone (GH) secretion to neurotransmission, metabolic homeostasis, gastrointestinal and immune function, and tumor cell growth. Thus, SST analogs are used to treat endocrine/tumoral pathologies. Yet, some SST/CORT actions cannot be explained by their interaction with known ssts. We recently identified novel sst5 variants in human, pig, mouse, and rat that lack one or more TMDs and display unique molecular/functional features: they exhibit distinct tissue distribution, divergent responses to SST/CORT, and intracellular localization as opposed to the typical plasma-membrane distribution of full-length ssts. When coexpressed in the same cell, truncated sst5 variants colocalize and physically interact with full-length ssts, providing a molecular basis to disrupt normal sst2/sst5 functioning. This may explain the inverse correlation between hsst5TMD4 expression in pituitary tumors and octreotide responsiveness in acromegaly. Discovery of these new truncated sst5 variants provides novel insights on SST/CORT/sst pathophysiology and suggests new research avenues for the therapeutic potential of this system.
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Affiliation(s)
- José Córdoba-Chacón
- Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Instituto Maimónides de Investigación Biomédica de Córdoba, Córdoba, Spain
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Tsitoura P, Andronopoulou E, Tsikou D, Agalou A, Papakonstantinou MP, Kotzia GA, Labropoulou V, Swevers L, Georgoussi Z, Iatrou K. Expression and membrane topology of Anopheles gambiae odorant receptors in lepidopteran insect cells. PLoS One 2010; 5:e15428. [PMID: 21082026 PMCID: PMC2972716 DOI: 10.1371/journal.pone.0015428] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Accepted: 09/21/2010] [Indexed: 12/21/2022] Open
Abstract
A lepidopteran insect cell-based expression system has been employed to express three Anopheles gambiae odorant receptors (ORs), OR1 and OR2, which respond to components of human sweat, and OR7, the ortholog of Drosophila's OR83b, the heteromerization partner of all functional ORs in that system. With the aid of epitope tagging and specific antibodies, efficient expression of all ORs was demonstrated and intrinsic properties of the proteins were revealed. Moreover, analysis of the orientation of OR1 and OR2 on the cellular plasma membrane through the use of a novel ‘topology screen’ assay and FACS analysis demonstrates that, as was recently reported for the ORs in Drosophila melanogaster, mosquito ORs also have a topology different than their mammalian counterparts with their N-terminal ends located in the cytoplasm and their C-terminal ends facing outside the cell. These results set the stage for the production of mosquito ORs in quantities that should permit their detailed biochemical and structural characterization and the exploration of their functional properties.
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Affiliation(s)
- Panagiota Tsitoura
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Evi Andronopoulou
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Daniela Tsikou
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Adamantia Agalou
- Laboratory of Cellular Signaling and Molecular Pharmacology, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Maria P. Papakonstantinou
- Laboratory of Cellular Signaling and Molecular Pharmacology, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Georgia A. Kotzia
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Vassiliki Labropoulou
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Luc Swevers
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Zafiroula Georgoussi
- Laboratory of Cellular Signaling and Molecular Pharmacology, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
| | - Kostas Iatrou
- Insect Molecular Genetics and Biotechnology Group, Institute of Biology, National Centre for Scientific Research “Demokritos”, Athens, Greece
- * E-mail:
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13
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Zmijewski MA, Slominski AT. Emerging role of alternative splicing of CRF1 receptor in CRF signaling. Acta Biochim Pol 2010; 57:1-13. [PMID: 20234885 PMCID: PMC2883312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2009] [Revised: 03/02/2010] [Accepted: 03/15/2010] [Indexed: 05/28/2023]
Abstract
Alternative splicing of mRNA is one of the most important mechanisms responsible for an increase of the genomic capacity. Thus the majority of human proteins including G protein-coupled receptors (GPCRs) possess several isoforms as a result of mRNA splicing. The corticotropin-releasing factor (CRF) and its receptors are the most proximal elements of hypothalamic-pituitary-adrenal axis (HPA) - the central machinery of stress response. Moreover, expression of CRF and regulated activity of CRF receptor type 1 (CRF1) can also play an important role in regulation of local stress response in peripheral tissues including skin, gastrointestinal tract or reproductive system. In humans, expression of at least eight variants of CRF1 mRNA (alpha, beta, c, d, e, f, g and h) was detected and alternative splicing was found to be regulated by diverse physiological and pathological factors including: growth conditions, onset of labor, during pregnancy or exposure to ultraviolet irradiation. The pattern of expression of CRF1 isoforms is cell type specific and recently has been linked to observed differences in responsiveness to CRF stimulation. In the proposed model of regulation of CRF-signaling, isoform CRF1alpha plays a central role. Other isoforms modulate its activity by oligomerization, leading to alteration in receptor trafficking, localization and function. Co-expression of CRF1 isoforms modulates sensitivity of cells to the ligands and influences downstream coupling to G-proteins. The other possible regulatory mechanisms include fast mRNA and/or protein turnover or decoy receptor function of CRF1 isoforms. Taken together, alternative splicing of CRF1 can represent another level of regulation of CRF-mediated stress responses at the central and peripheral levels. Chronic stress or malfunction of the HPA-axis have been linked to numerous human pathologies, suggesting that alternative splicing of CRF1 receptor could represent a promising target for drugs development.
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Affiliation(s)
- Michał A Zmijewski
- Department of Molecular Enzymology, Intercollegiate Faculty of Biotechnology of University of Gdańsk and Medical University of Gdańsk, Gdańsk, Poland.
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Almeida TA, Rodriguez Y, Hernández M, Reyes R, Bello AR. Differential expression of new splice variants of the neurotensin receptor 1 gene in human prostate cancer cell lines. Peptides 2010; 31:242-7. [PMID: 20018219 DOI: 10.1016/j.peptides.2009.12.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 12/04/2009] [Accepted: 12/04/2009] [Indexed: 11/18/2022]
Abstract
Neurotensin is a neuroendocrine peptide acting as a trophic factor in a variety of cells in vivo but it can also function as an autocrine growth factor in human prostate cancer cells in vitro. In addition, the high-affinity G protein-coupled NT receptor (NTS1) is overexpressed in prostate cancer cell lines. Increasing evidence argues for a direct correlation between specific alternative splice variants and cancer. We detected four splice variants of the NTS1 receptor in human prostate cancer cell lines. These isoforms include one or more exons skipping as well as an alternative 5' splice donor site and are expressed in the late-stage androgen independent prostate cancer cell lines PC3 and DU145, but not in the early-stage androgen-sensitive LNCaP or in normal prostate tissue, which only express the normal transcript. This result shows new splice variants of NTS1 for the first time. The differential expression observed among prostate cancer cell lines and normal prostate tissue opens the interesting possibility of a new role of NT/NTS1 pathway in prostate cancer.
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Affiliation(s)
- Teresa A Almeida
- Laboratorio de Genética, Instituto Universitario de Enfermedades Tropicales de Canarias, Universidad de La Laguna, Avda. Astrofísico Francisco Sánchez s/n, 38206 La Laguna, Canarias, Spain.
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15
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Markovic D, Challiss RAJ. Alternative splicing of G protein-coupled receptors: physiology and pathophysiology. Cell Mol Life Sci 2009; 66:3337-52. [PMID: 19629391 PMCID: PMC11115665 DOI: 10.1007/s00018-009-0093-4] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Revised: 06/30/2009] [Accepted: 07/03/2009] [Indexed: 12/16/2022]
Abstract
The G protein-coupled receptors (GPCRs) are a superfamily of transmembrane receptors that have a broad distribution and can collectively recognise a diverse array of ligands. Activation or inhibition of GPCR signalling can affect many (patho)physiological processes, and consequently they are a major target for existing and emerging drug therapies. A common observation has been that the pharmacological, signalling and regulatory properties of GPCRs can differ in a cell- and tissue-specific manner. Such "phenotypic" diversity might be attributable to post-translational modifications and/or association of GPCRs with accessory proteins, however, post-transcriptional mechanisms are also likely to contribute. Although approximately 50% of GPCR genes are intronless, those that possess introns can undergo alternative splicing, generating GPCR subtype isoforms that may differ in their pharmacological, signalling and regulatory properties. In this review we shall highlight recent research into GPCR splice variation and discuss the potential consequences this might have for GPCR function in health and disease.
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Affiliation(s)
- Danijela Markovic
- Department of Cell Physiology and Pharmacology, University of Leicester, Henry Wellcome Building, Leicester, UK.
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16
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Focus on the splicing of secretin GPCRs transmembrane-domain 7. Trends Biochem Sci 2009; 34:443-52. [PMID: 19733082 DOI: 10.1016/j.tibs.2009.06.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Revised: 05/20/2009] [Accepted: 06/04/2009] [Indexed: 12/17/2022]
Abstract
The family of G-protein coupled receptors (GPCRs) is one of the largest protein families in the mammalian genome with a fundamental role in cell biology. GPCR activity is finely tuned by various transcriptional, post-transcriptional and post-translational mechanisms. Alternative pre-mRNA splicing is now emerging as a crucial process regulating GPCR biological function. Intriguingly, this mechanism appears to extensively target the Secretin family of GPCRs, especially the exon that encodes a 14 amino acid sequence that forms the distal part of 7th transmembrane helix, and exhibits an unusually high level of sequence conservation among most Secretin GPCRs. Do the "TMD7-short" receptor variants have a role as novel regulators of GPCR signallng and, if so, what are the implications for hormonal actions and physiology?
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17
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Durán-Prado M, Gahete MD, Martínez-Fuentes AJ, Luque RM, Quintero A, Webb SM, Benito-López P, Leal A, Schulz S, Gracia-Navarro F, Malagón MM, Castaño JP. Identification and characterization of two novel truncated but functional isoforms of the somatostatin receptor subtype 5 differentially present in pituitary tumors. J Clin Endocrinol Metab 2009; 94:2634-43. [PMID: 19401364 DOI: 10.1210/jc.2008-2564] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
CONTEXT Somatostatin and its related peptide cortistatin exert multiple actions on normal and tumoral tissue targets through a family of receptors termed somatostatin receptor (sst)1-5. Despite the considerable advances in the knowledge on these receptors and their (patho)physiological roles, there is still evidence that additional receptors for these peptides should exist to fully explain their actions. OBJECTIVE The growing number of spliced variants found in similar receptor families, often present in tumors, and results from our group obtained on sst5 from other species (pig) led us to explore the existence of new human sst5 isoforms. DESIGN AND RESULTS A rapid amplification of cDNA ends PCR approach on samples from a human pituitary tumor and a cell line enabled identification of two novel alternatively spliced sst5 receptor variants. The sequences obtained encode putative proteins that correspond to truncated isoforms of five and four transmembrane domains (TMDs), accordingly named sst5TMD5 and sst5TMD4, respectively. Both novel receptors show a differential expression pattern in normal tissues and are also present in pituitary tumors of diverse etiology including nonfunctioning adenomas, corticotropinomas, somatotropinomas, and a prolactinoma. In contrast to the predominant plasma membrane localization of full-length sst5, both sst5TMD5 and sst5TMD4 show a preferentially intracellular localization. Despite their truncated nature, both receptors are functional, as shown by their ability to mediate selective, ligand-induced rises in free cytosolic calcium concentration. Specifically, whereas sst5TMD5 is selectivity activated by somatostatin compared with cortistatin, cells transfected with sst5TMD4 almost exclusively respond to cortistatin and not to somatostatin. CONCLUSIONS Our results demonstrate the existence of two previously unidentified sst5 spliced variants with distinct distribution in normal tissues and pituitary tumors, unique ligand-selective signaling properties, and subcellular distribution, which could contribute to somatostatin and cortistatin signaling in normal and tumoral cells.
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Affiliation(s)
- Mario Durán-Prado
- Department of Cell Biology, Physiology, and Immunology, University of Córdoba, and Centro de Investigación Biomédica en Red Fisiopatología de la Obesidad y Nutrición, E-14014 Córdoba Spain
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Markovic D, Lehnert H, Levine MA, Grammatopoulos DK. Structural determinants critical for localization and signaling within the seventh transmembrane domain of the type 1 corticotropin releasing hormone receptor: lessons from the receptor variant R1d. Mol Endocrinol 2008; 22:2505-19. [PMID: 18772229 DOI: 10.1210/me.2008-0177] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The type 1 CRH receptor (CRH-R1) plays a fundamental role in homeostatic adaptation to stressful stimuli. CRH-R1 gene activity is regulated through alternative splicing and generation of various CRH-R1 mRNA variants. One such variant is the CRH-R1d, which has 14 amino acids missing from the putative seventh transmembrane domain due to exon 13 deletion, a splicing event common to other members of the B1 family of G protein-coupled receptors. In this study, using overexpression of recombinant receptors in human embryonic kidney 293 and myometrial cells, we showed by confocal microscopy that in contrast to CRH-R1alpha, the R1d variant is primarily retained in the cytoplasm, although some cell membrane expression is also evident. Use of antibodies against the CRH-R1 C terminus in nonpermeabilized cells showed that membrane-expressed CRH-R1d contains an extracellular C terminus. Interestingly, treatment of CRH-R1d-expressing cells with CRH (100 nM) for 45-60 min elicited functional responses associated with a significant reduction of plasma membrane receptor expression, redistribution of intracellular receptors, and increased receptor degradation. Site-directed mutagenesis studies identified the cassette G356-F358 within transmembrane domain 7 as crucial for CRH-R1alpha stability to the plasma membrane because deletion of this cassette caused substantial intracellular localization of CRH-R1 alpha. Most importantly, coexpression studies between CRH-R1d and CRH-R2beta demonstrated that the CRH-R2beta could partially rescue CRH-R1d membrane expression, and this was associated with a significant attenuation of urocotrin II-induced cAMP production and ERK1/2 and p38MAPK activation, suggesting that CRH-R1d might specifically induce heterologous impairment of CRH-R2 signaling responses. This mechanism appears to involve accelerated CRH-R2beta endocytosis.
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Affiliation(s)
- Danijela Markovic
- Endocrinology and Metabolism, Clinical Sciences Institute, Warwick Medical School, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom
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Abstract
It is well established that calcitonin is a potent inhibitor of bone resorption; however, a physiological role for calcitonin acting through its cognate receptor, the calcitonin receptor (CTR), has not been identified. Data from previous genetically modified animal models have recognized a possible role for calcitonin and the CTR in controlling bone formation; however, interpretation of these data are complicated, in part because of their mixed genetic background. Therefore, to elucidate the physiological role of the CTR in calcium and bone metabolism, we generated a viable global CTR knockout (KO) mouse model using the Cre/loxP system, in which the CTR is globally deleted by >94% but <100%. Global CTRKOs displayed normal serum ultrafiltrable calcium levels and a mild increase in bone formation in males, showing that the CTR plays a modest physiological role in the regulation of bone and calcium homeostasis in the basal state in mice. Furthermore, the peak in serum total calcium after calcitriol [1,25(OH)(2)D(3)]-induced hypercalcemia was substantially greater in global CTRKOs compared with controls. These data provide strong evidence for a biological role of the CTR in regulating calcium homeostasis in states of calcium stress.
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Conner M, Hicks MR, Dafforn T, Knowles TJ, Ludwig C, Staddon S, Overduin M, Günther UL, Thome J, Wheatley M, Poyner DR, Conner AC. Functional and biophysical analysis of the C-terminus of the CGRP-receptor; a family B GPCR. Biochemistry 2008; 47:8434-44. [PMID: 18636754 DOI: 10.1021/bi8004126] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
G-protein coupled receptors (GPCRs) typically have a functionally important C-terminus which, in the largest subfamily (family A), includes a membrane-parallel eighth helix. Mutations of this region are associated with several diseases. There are few C-terminal studies on the family B GPCRs and no data supporting the existence of a similar eighth helix in this second major subfamily, which has little or no sequence homology to family A GPCRs. Here we show that the C-terminus of a family B GPCR (CLR) has a disparate region from N400 to C436 required for CGRP-mediated internalization, and a proximal region of twelve residues (from G388 to W399), in a similar position to the family A eighth helix, required for receptor localization at the cell surface. A combination of circular and linear dichroism, fluorescence and modified waterLOGSY NMR spectroscopy (SALMON) demonstrated that a peptide mimetic of this domain readily forms a membrane-parallel helix anchored to the liposome by an interfacial tryptophan residue. The study reveals two key functions held within the C-terminus of a family B GPCR and presents support for an eighth helical region with striking topological similarity to the nonhomologous family A receptor. This helix structure appears to be found in most other family B GPCRs.
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Long SH, Berna MJ, Thill M, Pace A, Pradhan TK, Hoffmann KM, Serrano J, Jensen RT. Secretin-receptor and secretin-receptor-variant expression in gastrinomas: correlation with clinical and tumoral features and secretin and calcium provocative test results. J Clin Endocrinol Metab 2007; 92:4394-402. [PMID: 17711922 PMCID: PMC2464459 DOI: 10.1210/jc.2007-0986] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
CONTEXT/OBJECTIVES The diagnosis of Zollinger-Ellison syndrome requires secretin testing in 60% of patients. Even with secretin, the diagnosis may be difficult because variable responses occur, and 6-30% have negative testing. The basis for variability or negative responses is unclear. It is unknown whether the tumor density of secretin receptors or the presence of a secretin-receptor-variant, which can act as a dominant negative, is important. The aim of this study was to investigate these possibilities. PATIENTS/METHODS Secretin-receptor and variant mRNA expression was determined in gastrinomas using real-time PCR from 54 Zollinger-Ellison syndrome patients. Results were correlated with Western blotting, secretin-receptor immunohistochemistry, with gastrin-provocative test results and tumoral/clinical/laboratory features. RESULTS Secretin-receptor mRNA was detectible in all gastrinomas but varied 132-fold with a mean of 0.89 +/- 0.12 molecules per beta-actin. Secretin-receptor PCR results correlated closely with Western blotting (r = 0.95; P < 0.0001) and receptor immunohistochemistry (P = 0.0015; r = 0.71). The variant was detected in all gastrinomas, but levels varied 102-fold and were 72-fold lower than the total. Secretin-receptor levels correlated with variant levels, Deltasecretin, but not Deltacalcium and with tumor location, but not growth, extent, or clinical responses. Variant levels did not correlate with the Deltasecretin. Detailed analysis provides no evidence that variant expression modified the secretin-receptor response or accounted for negative tests. CONCLUSIONS Secretin-receptor and secretin-receptor-variant expressions occur in all gastrinomas. Because the expression of the total, but not variant, correlated with the secretin results and no evidence for dominant negative activity of the variant was found, our results suggest that the total secretin-receptor density is an important determinant of the secretin test response.
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Affiliation(s)
- Scott H Long
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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Nag K, Sultana N, Kato A, Hirose S. Headless splice variant acting as dominant negative calcitonin receptor. Biochem Biophys Res Commun 2007; 362:1037-43. [PMID: 17822673 DOI: 10.1016/j.bbrc.2007.08.107] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2007] [Accepted: 08/18/2007] [Indexed: 11/20/2022]
Abstract
Calcitonin receptor (CTR) is a member of class B G protein-coupled receptor (GPCR) superfamily. We have recently identified the CTR gene and its two transcriptional isoforms, mfCTR and mfCTRDeltaN, in mefugu (mf) (Takifugu obscurus). Here we characterized the mfCTRDeltaN that lacks hormone-binding extracellular N-terminal domain. Strong expression in the liver and weak but broad tissue distribution of its mRNA, revealed by Northern analysis, suggested physiological significance of this headless splice variant. Biochemical and immunocytochemical analyses revealed that it acts as a naturally occurring dominant negative isoform by forming a heterodimer with normal CTR. The headless mfCTRDeltaN characterized here is the first case of N-terminally truncated dominant negative form of GPCR, and immunocytochemistry used for detecting the heterodimer formation may be useful as a novel method for analyzing membrane protein interaction in a living cell.
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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
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Hillhouse EW, Grammatopoulos DK. The molecular mechanisms underlying the regulation of the biological activity of corticotropin-releasing hormone receptors: implications for physiology and pathophysiology. Endocr Rev 2006; 27:260-86. [PMID: 16484629 DOI: 10.1210/er.2005-0034] [Citation(s) in RCA: 272] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The CRH receptor (CRH-R) is a member of the secretin family of G protein-coupled receptors. Wide expression of CRH-Rs in the central nervous system and periphery ensures that their cognate agonists, the family of CRH-like peptides, are capable of exerting a wide spectrum of actions that underpin their critical role in integrating the stress response and coordinating the activity of fundamental physiological functions, such as the regulation of the cardiovascular system, energy balance, and homeostasis. Two types of mammal CRH-R exist, CRH-R1 and CRH-R2, each with unique splicing patterns and remarkably distinct pharmacological properties, but similar signaling properties, probably reflecting their distinct and sometimes contrasting biological functions. The regulation of CRH-R expression and activity is not fully elucidated, and we only now begin to fully understand the impact on mammalian pathophysiology. The focus of this review is the current and evolving understanding of the molecular mechanisms controlling CRH-R biological activity and functional flexibility. This shows notable tissue-specific characteristics, highlighted by their ability to couple to distinct G proteins and activate tissue-specific signaling cascades. The type of activating agonist, receptor, and target cell appears to play a major role in determining the overall signaling and biological responses in health and disease.
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Affiliation(s)
- Edward W Hillhouse
- The Leeds Institute of Genetics, Health and Therapeutics, The University of Leeds, Leeds LS2 9NL, UK.
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