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Hu B, Lv X, Wei L, Wang Y, Zheng G, Yang C, Zang F, Wang J, Li J, Wu X, Yue Z, Xiao Q, Shao Z, Yuan W, Li J, Cao P, Xu C, Chen H. Sensory Nerve Maintains Intervertebral Disc Extracellular Matrix Homeostasis Via CGRP/CHSY1 Axis. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2202620. [PMID: 36047655 PMCID: PMC9596848 DOI: 10.1002/advs.202202620] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 07/22/2022] [Indexed: 06/01/2023]
Abstract
Sensory nerves are long being recognized as collecting units of various outer stimuli; recent advances indicate that the sensory nerve also plays pivotal roles in maintaining organ homeostasis. Here, this study shows that sensory nerve orchestrates intervertebral disc (IVD) homeostasis by regulating its extracellular matrix (ECM) metabolism. Specifically, genetical sensory denervation of IVD results in loss of IVD water preserve molecule chondroitin sulfate (CS), the reduction of CS bio-synthesis gene chondroitin sulfate synthase 1 (CHSY1) expression, and dysregulated ECM homeostasis of IVD. Particularly, knockdown of sensory neuros calcitonin gene-related peptide (CGRP) expression induces similar ECM metabolic disorder compared to sensory nerve denervation model, and this effect is abolished in CHSY1 knockout mice. Furthermore, in vitro evidence shows that CGRP regulates nucleus pulposus cell CHSY1 expression and CS synthesis via CGRP receptor component receptor activity-modifying protein 1 (RAMP1) and cyclic AMP response element-binding protein (CREB) signaling. Therapeutically, local injection of forskolin significantly attenuates IVD degeneration progression in mouse annulus fibrosus puncture model. Overall, these results indicate that sensory nerve maintains IVD ECM homeostasis via CGRP/CHSY1 axis and promotes IVD repair, and this expands the understanding concerning how IVD links to sensory nerve system, thus shedding light on future development of novel therapeutical strategy to IVD degeneration.
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Affiliation(s)
- Bo Hu
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Xiao Lv
- Department of OrthopaedicsUnion HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan430022China
| | - Leixin Wei
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Yunhao Wang
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Genjiang Zheng
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Chen Yang
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Fazhi Zang
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Jianxi Wang
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Jing Li
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Xiaodong Wu
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Zhihao Yue
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Qiangqiang Xiao
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Zengwu Shao
- Department of OrthopaedicsUnion HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan430022China
| | - Wen Yuan
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Jinsong Li
- State Key Laboratory of Cell BiologyShanghai Key Laboratory of Molecular AndrologyCAS Center for Excellence in Molecular Cell ScienceInstitute of Biochemistry and Cell BiologyChinese Academy of ScienceShanghai200031China
| | - Peng Cao
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Chen Xu
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
| | - Huajiang Chen
- Spine CenterDepartment of OrthopedicsChangzheng HospitalNaval Medical UniversityShanghai200003China
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Kuenzel WJ, Kang SW, Jurkevich A. The vasotocinergic system and its role in the regulation of stress in birds. VITAMINS AND HORMONES 2019; 113:183-216. [PMID: 32138948 DOI: 10.1016/bs.vh.2019.10.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The regulation of stress in birds includes a complex interaction of neural systems affecting the hypothalamic-pituitary-adrenal (HPA) axis. In addition to the hypothalamic paraventricular nucleus, a structure called the nucleus of the hippocampal commissure likewise affects the output of pituitary stress hormones and appears to be unique to avian species. Within the anterior pituitary, the avian V1a and V1b receptors were found in corticotropes. Based on our studies with central administration of hormones in the chicken, corticotropic releasing hormone (CRH) is a more potent ACTH secretagogue than arginine vasotocin (AVT). In contrast, when applied peripherally, AVT is more efficacious. Co-administration of AVT and CRH peripherally, resulted in a synergistic stimulation of corticosterone release. Data suggest receptor oligomerization as one possible mechanism. In birds, vasotocin receptors associated with stress responses include the V1a and V1b receptors. Three-dimensional, homology-based structural models of the avian V1aR were built to test agonists and antagonists for each receptor that were screened by molecular docking to map their binding sites on each receptor. Additionally, binding affinity values for each available peptide antagonist to the V1aR and V1bR were determined. An anterior pituitary primary culture system was developed to determine how effective each antagonist blocked the function of each receptor in culture when stimulated by a combination of AVT/CRH administration. Use of an antagonist in subsequent in vivo studies identified the V1aR in regulating food intake in birds. The V1aR was likewise found in circumventricular organs of the brain, suggesting a possible function in stress.
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Affiliation(s)
- Wayne J Kuenzel
- Poultry Science Center, University of Arkansas, Fayetteville, AR, United States.
| | - Seong W Kang
- Poultry Science Center, University of Arkansas, Fayetteville, AR, United States
| | - Alexander Jurkevich
- Molecular Cytology Research Core Facility, University of Missouri, Columbia, MO, United States
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Mackie DI, Al Mutairi F, Davis RB, Kechele DO, Nielsen NR, Snyder JC, Caron MG, Kliman HJ, Berg JS, Simms J, Poyner DR, Caron KM. h CALCRL mutation causes autosomal recessive nonimmune hydrops fetalis with lymphatic dysplasia. J Exp Med 2018; 215:2339-2353. [PMID: 30115739 PMCID: PMC6122977 DOI: 10.1084/jem.20180528] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 06/15/2018] [Accepted: 07/26/2018] [Indexed: 01/19/2023] Open
Abstract
Using genetic, pharmacological and animal model approaches, we elucidate a novel human mutation in a G protein coupled receptor that impairs receptor oligomerization and trafficking leading to fatal, non-immune hydrops fetalis associated with arrested lymphatic development. We report the first case of nonimmune hydrops fetalis (NIHF) associated with a recessive, in-frame deletion of V205 in the G protein–coupled receptor, Calcitonin Receptor-Like Receptor (hCALCRL). Homozygosity results in fetal demise from hydrops fetalis, while heterozygosity in females is associated with spontaneous miscarriage and subfertility. Using molecular dynamic modeling and in vitro biochemical assays, we show that the hCLR(V205del) mutant results in misfolding of the first extracellular loop, reducing association with its requisite receptor chaperone, receptor activity modifying protein (RAMP), translocation to the plasma membrane and signaling. Using three independent genetic mouse models we establish that the adrenomedullin–CLR–RAMP2 axis is both necessary and sufficient for driving lymphatic vascular proliferation. Genetic ablation of either lymphatic endothelial Calcrl or nonendothelial Ramp2 leads to severe NIHF with embryonic demise and placental pathologies, similar to that observed in humans. Our results highlight a novel candidate gene for human congenital NIHF and provide structure–function insights of this signaling axis for human physiology.
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Affiliation(s)
- Duncan I Mackie
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC
| | - Fuad Al Mutairi
- Department of Pediatrics, King Abdulaziz Medical City, Riyadh, Saudi Arabia .,King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia.,King Abdullah International Medical Research Centre (KAIMRC), Riyadh, Saudi Arabia
| | - Reema B Davis
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC
| | - Daniel O Kechele
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC
| | - Natalie R Nielsen
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC
| | - Joshua C Snyder
- Department of Cell Biology, Duke University Medical Center, Durham, NC.,Department of Surgery, Duke University Medical Center, Durham, NC
| | - Marc G Caron
- Department of Cell Biology, Duke University Medical Center, Durham, NC
| | - Harvey J Kliman
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale University School of Medicine, New Haven, CT
| | - Jonathan S Berg
- Department of Genetics, University of North Carolina, Chapel Hill, NC
| | - John Simms
- School of Life Sciences, Faculty of Health and Life Sciences, Coventry University, Coventry, England, UK
| | - David R Poyner
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, England, UK
| | - Kathleen M Caron
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC .,Department of Genetics, University of North Carolina, Chapel Hill, NC
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Kang SW, Jayanthi S, Nagarajan G, Suresh Kumar TK, Kuenzel WJ. Identification of avian vasotocin receptor subtype-specific antagonists involved in the stress response of the chicken, Gallus gallus. J Biomol Struct Dyn 2018; 37:1685-1699. [PMID: 29658387 DOI: 10.1080/07391102.2018.1464957] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Vasotocin 1a and 1b receptors (V1aR and V1bR) have been shown to play important roles in the neuroendocrine regulation of stress responses via the anterior pituitary (AP) of birds. To identify effective subtype-specific antagonists for the chicken V1aR (cV1aR) and cV1bR, potential antagonists to the mammalian V1R were screened against the cV1aR and cV1bR 3D structural models by molecular docking analysis with determination of binding pocket/amino acid residues involved in the interaction. The antagonistic effects of the selected ligands were examined by measuring pro-opiomelanocortin (POMC) heteronuclear RNA (hnPOMC) levels following the in vitro stress administration to primary chicken AP cells. Results of in silico analysis showed that the Manning compound and several other antagonists were bound to cV1bR with higher affinity than the natural agonist, arginine vasotocin (AVT). Similarities and differences in the antagonist-receptor binding interface with receptors were characterized for each ligand. Non-peptide mammalian V1bR antagonists, SSR-149415 and L-368899, were shown to be effective and had an additive effect in blocking POMC hnRNA expression in pituitary cell culture studies. SR-49059 antagonized the effect(s) of AVT/CRH on the downregulation of the cV1aR and the upregulation of the cCRH-R2 expression but not the cV1bR and cCRH-R1. The Manning compound antagonized the downregulation of cV1aR, cV1bR and cCRH-R1 and the upregulation of cCRH-R2 expression. The specificity of antagonists apparently resulted from unique differences in the interacting residues and their binding affinities. Collectively, these results provide valuable leads for future development of novel compounds capable of blocking or attenuating the AP stress response of avian species and perhaps other non-mammalian vertebrates as well.
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Affiliation(s)
- Seong W Kang
- a Department of Poultry Sciences , University of Arkansas , Fayetteville , AR , USA
| | - Srinivas Jayanthi
- b Department of Chemistry and Biochemistry , University of Arkansas , Fayetteville , AR , USA
| | - Gurueswar Nagarajan
- a Department of Poultry Sciences , University of Arkansas , Fayetteville , AR , USA
| | | | - Wayne J Kuenzel
- a Department of Poultry Sciences , University of Arkansas , Fayetteville , AR , USA
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Opportunities for therapeutic antibodies directed at G-protein-coupled receptors. Nat Rev Drug Discov 2017; 16:787-810. [PMID: 28706220 DOI: 10.1038/nrd.2017.91] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
G-protein-coupled receptors (GPCRs) are activated by a diverse range of ligands, from large proteins and proteases to small peptides, metabolites, neurotransmitters and ions. They are expressed on all cells in the body and have key roles in physiology and homeostasis. As such, GPCRs are one of the most important target classes for therapeutic drug discovery. The development of drugs targeting GPCRs has therapeutic value across a wide range of diseases, including cancer, immune and inflammatory disorders as well as neurological and metabolic diseases. The progress made by targeting GPCRs with antibody-based therapeutics, as well as technical hurdles to overcome, are presented and discussed in this Review. Antibody therapeutics targeting C-C chemokine receptor type 4 (CCR4), CCR5 and calcitonin gene-related peptide (CGRP) are used as illustrative clinical case studies.
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Dong M, Koole C, Wootten D, Sexton PM, Miller LJ. Structural and functional insights into the juxtamembranous amino-terminal tail and extracellular loop regions of class B GPCRs. Br J Pharmacol 2014; 171:1085-101. [PMID: 23889342 DOI: 10.1111/bph.12293] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 06/22/2013] [Accepted: 06/29/2013] [Indexed: 12/24/2022] Open
Abstract
Class B guanine nucleotide-binding protein GPCRs share heptahelical topology and signalling via coupling with heterotrimeric G proteins typical of the entire superfamily of GPCRs. However, they also exhibit substantial structural differences from the more extensively studied class A GPCRs. Even their helical bundle region, most conserved across the superfamily, is predicted to differ from that of class A GPCRs. Much is now known about the conserved structure of the amino-terminal domain of class B GPCRs, coming from isolated NMR and crystal structures, but the orientation of that domain relative to the helical bundle is unknown, and even less is understood about the conformations of the juxtamembranous amino-terminal tail or of the extracellular loops linking the transmembrane segments. We now review what is known about the structure and function of these regions of class B GPCRs. This comes from indirect analysis of structure-function relationships elucidated by mutagenesis and/or ligand modification and from the more direct analysis of spatial approximation coming from photoaffinity labelling and cysteine trapping studies. Also reviewed are the limited studies of structure of some of these regions. No dominant theme was recognized for the structures or functional roles of distinct regions of these juxtamembranous portions of the class B GPCRs. Therefore, it is likely that a variety of molecular strategies can be engaged for docking of agonist ligands and for initiation of conformational changes in these receptors that would be expected to converge to a common molecular mechanism for activation of intracellular signalling cascades.
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Affiliation(s)
- M Dong
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, USA
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7
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Hay DL, Harris PWR, Kowalczyk R, Brimble MA, Rathbone DL, Barwell J, Conner AC, Poyner DR. Structure-activity relationships of the N-terminus of calcitonin gene-related peptide: key roles of alanine-5 and threonine-6 in receptor activation. Br J Pharmacol 2014; 171:415-26. [PMID: 24125506 PMCID: PMC3904261 DOI: 10.1111/bph.12464] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 09/10/2013] [Accepted: 10/07/2013] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND AND PURPOSE The N-terminus of calcitonin gene-related peptide (CGRP) is important for receptor activation, especially the disulphide-bonded ring (residues 1-7). However, the roles of individual amino acids within this region have not been examined and so the molecular determinants of agonism are unknown. This study has examined the role of residues 1, 3-6 and 8-9, excluding Cys-2 and Cys-7. EXPERIMENTAL APPROACH CGRP derivatives were substituted with either cysteine or alanine; further residues were introduced at position 6. Their affinity was measured by radioligand binding and their efficacy by measuring cAMP production in SK-N-MC cells and β-arrestin 2 translocation in CHO-K1 cells at the CGRP receptor. KEY RESULTS Substitution of Ala-5 by cysteine reduced affinity 270-fold and reduced efficacy for production of cAMP in SK-N-MCs. Potency at β-arrestin translocation was reduced by ninefold. Substitution of Thr-6 by cysteine destroyed all measurable efficacy of both cAMP and β-arrestin responses; substitution with either alanine or serine impaired potency. Substitutions at positions 1, 4, 8 and 9 resulted in approximately 10-fold reductions in potency at both responses. Similar observations were made at a second CGRP-activated receptor, the AMY(1(a)) receptor. CONCLUSIONS AND IMPLICATIONS Ala-5 and Thr-6 are key determinants of agonist activity for CGRP. Ala-5 is also very important for receptor binding. Residues outside of the 1-7 ring also contribute to agonist activity.
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Affiliation(s)
- Debbie L Hay
- School of Biological Sciences and Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland, New Zealand
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Wong WC, Maurer-Stroh S, Eisenhaber B, Eisenhaber F. On the necessity of dissecting sequence similarity scores into segment-specific contributions for inferring protein homology, function prediction and annotation. BMC Bioinformatics 2014; 15:166. [PMID: 24890864 PMCID: PMC4061105 DOI: 10.1186/1471-2105-15-166] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 05/27/2014] [Indexed: 02/01/2023] Open
Abstract
Background Protein sequence similarities to any types of non-globular segments (coiled coils, low complexity regions, transmembrane regions, long loops, etc. where either positional sequence conservation is the result of a very simple, physically induced pattern or rather integral sequence properties are critical) are pertinent sources for mistaken homologies. Regretfully, these considerations regularly escape attention in large-scale annotation studies since, often, there is no substitute to manual handling of these cases. Quantitative criteria are required to suppress events of function annotation transfer as a result of false homology assignments. Results The sequence homology concept is based on the similarity comparison between the structural elements, the basic building blocks for conferring the overall fold of a protein. We propose to dissect the total similarity score into fold-critical and other, remaining contributions and suggest that, for a valid homology statement, the fold-relevant score contribution should at least be significant on its own. As part of the article, we provide the DissectHMMER software program for dissecting HMMER2/3 scores into segment-specific contributions. We show that DissectHMMER reproduces HMMER2/3 scores with sufficient accuracy and that it is useful in automated decisions about homology for instructive sequence examples. To generalize the dissection concept for cases without 3D structural information, we find that a dissection based on alignment quality is an appropriate surrogate. The approach was applied to a large-scale study of SMART and PFAM domains in the space of seed sequences and in the space of UniProt/SwissProt. Conclusions Sequence similarity core dissection with regard to fold-critical and other contributions systematically suppresses false hits and, additionally, recovers previously obscured homology relationships such as the one between aquaporins and formate/nitrite transporters that, so far, was only supported by structure comparison.
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Affiliation(s)
- Wing-Cheong Wong
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, #07-01, Matrix, Singapore 138671, Singapore.
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Watkins HA, Rathbone DL, Barwell J, Hay DL, Poyner DR. Structure-activity relationships for α-calcitonin gene-related peptide. Br J Pharmacol 2013; 170:1308-22. [PMID: 23186257 PMCID: PMC3838678 DOI: 10.1111/bph.12072] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 10/11/2012] [Accepted: 11/15/2012] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED Calcitonin gene-related peptide (CGRP) is a member of the calcitonin (CT) family of peptides. It is a widely distributed neuropeptide implicated in conditions such as neurogenic inflammation. With other members of the CT family, it shares an N-terminal disulphide-bonded ring which is essential for biological activity, an area of potential α-helix, and a C-terminal amide. CGRP binds to the calcitonin receptor-like receptor (CLR) in complex with receptor activity-modifying protein 1 (RAMP1), a member of the family B (or secretin-like) GPCRs. It can also activate other CLR or calcitonin-receptor/RAMP complexes. This 37 amino acid peptide comprises the N-terminal ring that is required for receptor activation (residues 1-7); an α-helix (residues 8-18), a region incorporating a β-bend (residues 19-26) and the C-terminal portion (residues 27-37), that is characterized by bends between residues 28-30 and 33-34. A few residues have been identified that seem to make major contributions to receptor binding and activation, with a larger number contributing either to minor interactions (which collectively may be significant), or to maintaining the conformation of the bound peptide. It is not clear if CGRP follows the pattern of other family B GPCRs in binding largely as an α-helix. LINKED ARTICLES This article is part of a themed section on Neuropeptides. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.170.issue-7.
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Affiliation(s)
- Harriet A Watkins
- School of Biological Sciences, University of AucklandAuckland, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, University of AucklandAuckland, New Zealand
| | - Dan L Rathbone
- School of Life and Health Sciences, Aston UniversityBirmingham, UK
| | - James Barwell
- School of Life and Health Sciences, Aston UniversityBirmingham, UK
| | - Debbie L Hay
- School of Biological Sciences, University of AucklandAuckland, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, University of AucklandAuckland, New Zealand
| | - David R Poyner
- School of Life and Health Sciences, Aston UniversityBirmingham, UK
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Abstract
PURPOSE OF REVIEW The review summarizes the past year's literature, basic science and clinical, regarding the neural, paracrine, hormonal, and intracellular regulation of gastric acid secretion. RECENT FINDINGS Gastric acid facilitates the digestion of protein as well as the absorption of iron, calcium, vitamin B(12), and certain medications (e.g. thyroxin). It also kills ingested microorganisms and prevents bacterial overgrowth, enteric infection, and possibly spontaneous bacterial peritonitis. Stimulants of acid secretion include histamine, gastrin, acetylcholine, and ghrelin. Inhibitors include somatostatin, nefstatin-1, interleukin-11, and calcitonin gene-related peptide. Helicobacter pylori stimulates or inhibits acid secretion depending upon the time course of infection and the area of the stomach predominantly infected. Acute infection activates calcitonin gene-related peptide sensory neurons coupled to inhibition of histamine and acid secretion. Serum chromogranin A, a marker for neuroendocrine tumors, is elevated in patients taking proton pump inhibitors. SUMMARY Progress continues in our understanding of the regulation of gastric acid secretion in health and disease, as well as the function of gastric neuroendocrine cells. The recognition that gastrin is not only a secretagogue but also a trophic hormone has led to new research into the role of gastrin and its receptor (cholecystokinin-2 receptor) in carcinogenesis and the development of cholecystokinin-2 receptor antagonists.
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Kleinau G, Neumann S, Grüters A, Krude H, Biebermann H. Novel insights on thyroid-stimulating hormone receptor signal transduction. Endocr Rev 2013; 34:691-724. [PMID: 23645907 PMCID: PMC3785642 DOI: 10.1210/er.2012-1072] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The TSH receptor (TSHR) is a member of the glycoprotein hormone receptors, a subfamily of family A G protein-coupled receptors. The TSHR is of great importance for the growth and function of the thyroid gland. The TSHR and its endogenous ligand TSH are pivotal proteins with respect to a variety of physiological functions and malfunctions. The molecular events of TSHR regulation can be summarized as a process of signal transduction, including signal reception, conversion, and amplification. The steps during signal transduction from the extra- to the intracellular sites of the cell are not yet comprehensively understood. However, essential new insights have been achieved in recent years on the interrelated mechanisms at the extracellular region, the transmembrane domain, and intracellular components. This review contains a critical summary of available knowledge of the molecular mechanisms of signal transduction at the TSHR, for example, the key amino acids involved in hormone binding or in the structural conformational changes that lead to G protein activation or signaling regulation. Aspects of TSHR oligomerization, signaling promiscuity, signaling selectivity, phenotypes of genetic variations, and potential extrathyroidal receptor activity are also considered, because these are relevant to an understanding of the overall function of the TSHR, including physiological, pathophysiological, and pharmacological perspectives. Directions for future research are discussed.
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Affiliation(s)
- Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, Ostring 3, Augustenburger Platz 1, 13353 Berlin, Germany.
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12
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Abstract
The CGRP (calcitonin gene-related peptide) receptor is a family B GPCR (G-protein-coupled receptor). It consists of a GPCR, CLR (calcitonin receptor-like receptor) and an accessory protein, RAMP1 (receptor activity modifying protein 1). RAMP1 is needed for CGRP binding and also cell-surface expression of CLR. CLR is an example of a family B GPCR. Unlike family A GPCRs, little is known about how these receptors are activated by their endogenous ligands. This review considers what is known about the activation of family B GPCRs and then considers how this might be applied to CLR, particularly in light of new knowledge of the crystal structures of family A GPCRs.
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Müller A, Kleinau G, Piechowski CL, Müller TD, Finan B, Pratzka J, Grüters A, Krude H, Tschöp M, Biebermann H. G-protein coupled receptor 83 (GPR83) signaling determined by constitutive and zinc(II)-induced activity. PLoS One 2013; 8:e53347. [PMID: 23335960 PMCID: PMC3546042 DOI: 10.1371/journal.pone.0053347] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 11/27/2012] [Indexed: 12/31/2022] Open
Abstract
The G-protein coupled receptor 83 (GPR83) is an orphan G-protein coupled receptor for which the natural ligand(s) and signaling pathway(s) remain to be identified. Previous studies suggest a role of GPR83 in the regulation of thermogenesis and the control of circulating adiponectin. The aim of this study was to gain insights into the molecular underpinnings underlying GPR83 signaling. In particular, we aimed to assess the underlying G-protein activated signaling pathway of GPR83 and how this pathway is affected by mutational activation and zinc(II) challenge. Finally, we assessed the capacity of GPR83 for homodimerization. Our results show for the first time that mouse (m) GPR83 has high basal Gq/11 activity without affecting Gi or Gs signaling. Furthermore, we found that, under physiological conditions, zinc(II) (but not calcium(II) and magnesium(II)) potently activates mGPR83, thus identifying zinc(II) as an endogenous molecule with agonistic capability to activate mGPR83. In line with the observation that zinc(II)-ions activate mGPR83, we identified a cluster of ion-binding sensitive amino acids (e.g. His145, His204, Cys207, Glu217) in an activation sensitive receptor region of mGPR83. The occurrence of a constitutive activating mutant and a zinc(II)-binding residue at the N-terminal part corroborate the importance of this region in mGPR83 signal regulation. Finally, our results indicate that mGPR83 forms homodimers, which extend the current knowledge and molecular facets of GPR83 signaling.
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Affiliation(s)
- Anne Müller
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Carolin L. Piechowski
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Timo D. Müller
- Institute of Diabetes and Obesity, Helmholtz Center Munich, German Research Center for Environmental Health (GmbH), Munich, Germany
| | - Brian Finan
- Institute of Diabetes and Obesity, Helmholtz Center Munich, German Research Center for Environmental Health (GmbH), Munich, Germany
| | - Juliane Pratzka
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Annette Grüters
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Heiko Krude
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Matthias Tschöp
- Institute of Diabetes and Obesity, Helmholtz Center Munich, German Research Center for Environmental Health (GmbH), Munich, Germany
- Department of Metabolic Diseases, Technical University, Munich, Germany
| | - Heike Biebermann
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
- * E-mail:
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Vohra S, Taddese B, Conner AC, Poyner DR, Hay DL, Barwell J, Reeves PJ, Upton GJG, Reynolds CA. Similarity between class A and class B G-protein-coupled receptors exemplified through calcitonin gene-related peptide receptor modelling and mutagenesis studies. J R Soc Interface 2012; 10:20120846. [PMID: 23235263 PMCID: PMC3565703 DOI: 10.1098/rsif.2012.0846] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Modelling class B G-protein-coupled receptors (GPCRs) using class A GPCR structural templates is difficult due to lack of homology. The plant GPCR, GCR1, has homology to both class A and class B GPCRs. We have used this to generate a class A–class B alignment, and by incorporating maximum lagged correlation of entropy and hydrophobicity into a consensus score, we have been able to align receptor transmembrane regions. We have applied this analysis to generate active and inactive homology models of the class B calcitonin gene-related peptide (CGRP) receptor, and have supported it with site-directed mutagenesis data using 122 CGRP receptor residues and 144 published mutagenesis results on other class B GPCRs. The variation of sequence variability with structure, the analysis of polarity violations, the alignment of group-conserved residues and the mutagenesis results at 27 key positions were particularly informative in distinguishing between the proposed and plausible alternative alignments. Furthermore, we have been able to associate the key molecular features of the class B GPCR signalling machinery with their class A counterparts for the first time. These include the [K/R]KLH motif in intracellular loop 1, [I/L]xxxL and KxxK at the intracellular end of TM5 and TM6, the NPXXY/VAVLY motif on TM7 and small group-conserved residues in TM1, TM2, TM3 and TM7. The equivalent of the class A DRY motif is proposed to involve Arg2.39, His2.43 and Glu3.46, which makes a polar lock with T6.37. These alignments and models provide useful tools for understanding class B GPCR function.
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Affiliation(s)
- Shabana Vohra
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK
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