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Messeha SS, Agarwal M, Gendy SG, Mehboob SB, Soliman KFA. The Anti-Obesogenic Effects of Muscadine Grapes through Ciliary Neurotrophic Factor Receptor (Cntfr) and Histamine Receptor H1 (Hrh1) Genes in 3T3-L1 Differentiated Mouse Cells. Nutrients 2024; 16:1817. [PMID: 38931172 PMCID: PMC11206641 DOI: 10.3390/nu16121817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2024] [Revised: 06/06/2024] [Accepted: 06/07/2024] [Indexed: 06/28/2024] Open
Abstract
Obesity and type 2 diabetes are prevalent metabolic diseases that have significant links to several chronic diseases, including cancer, diabetes, hypertension, and cardiovascular disease. Muscadine grape extracts have shown the potential to reduce adiposity and improve insulin sensitivity and glucose control. Thus, this study was designed to determine the potential of muscadine grape berries extract (Pineapple and Southern Home) for its antiobesity properties in 3T3-L1 cells as a model for obesity research. The current study's data indicated the total phenolic content (TPC) and 2,2-diphenyl-1-picrylhydraziyl (DPPH) activity were higher in cultivar (CV) Southern Home, meanwhile, elevated the total flavonoid content (TFC) in Pineapple. Both extracts were safe across the tested range (0-5 mg/mL). A noticeable reduction in lipid accumulation was also found in extract-treated cells. In preadipocytes and adipocytes, the tested extracts showed significant alterations in various genes involved in glucose homeostasis and obesity. The most remarkable findings of the current study are the upregulation of two genes, Cntfr (+712.715-fold) and Hrh1 (+270.11-fold) in CV Pineapple extract-treated adipocytes 3T3-L1 and the high fold increase in Ramp3 induced by both Pineapple and Southern Home in pre-adipose cells. Furthermore, the tested extracts showed a potential to alter the mRNA of various genes, including Zfp91, B2m, Nr3c1, Insr, Atrn, Il6ra, Hsp90ab1, Sort1, and Npy1r. In conclusion, the data generated from the current study suggested that the two extracts under investigation are considered potential candidates for controlling insulin levels and managing obesity.
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Affiliation(s)
- Samia S. Messeha
- College of Science and Technology, Florida A&M University, Tallahassee, FL 32307, USA;
- College of Pharmacy and Pharmaceutical Sciences, Institute of Public Health, Florida A&M University, New Pharmacy Building, 1415 ML King Blvd., Tallahassee, FL 32307, USA
| | - Meenakshi Agarwal
- Center for Viticulture & Small Fruit Research, Florida A&M University, Tallahassee, FL 32317, USA;
| | - Sherif G. Gendy
- School of Allied Health Sciences, Florida A&M University, Tallahassee, FL 32307, USA;
| | - Sheikh B. Mehboob
- Center for Viticulture & Small Fruit Research, Florida A&M University, Tallahassee, FL 32317, USA;
| | - Karam F. A. Soliman
- College of Pharmacy and Pharmaceutical Sciences, Institute of Public Health, Florida A&M University, New Pharmacy Building, 1415 ML King Blvd., Tallahassee, FL 32307, USA
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Verbič A, Praznik A, Jerala R. A guide to the design of synthetic gene networks in mammalian cells. FEBS J 2020; 288:5265-5288. [PMID: 33289352 DOI: 10.1111/febs.15652] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 11/06/2020] [Accepted: 11/01/2020] [Indexed: 12/22/2022]
Abstract
Synthetic biology aims to harness natural and synthetic biological parts and engineering them in new combinations and systems, producing novel therapies, diagnostics, bioproduction systems, and providing information on the mechanism of function of biological systems. Engineering cell function requires the rewiring or de novo construction of cell information processing networks. Using natural and synthetic signal processing elements, researchers have demonstrated a wide array of signal sensing, processing and propagation modules, using transcription, translation, or post-translational modification to program new function. The toolbox for synthetic network design is ever-advancing and has still ample room to grow. Here, we review the diversity of synthetic gene networks, types of building modules, techniques of regulation, and their applications.
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Affiliation(s)
- Anže Verbič
- Department of Synthetic Biology and Immunology, National Institute of Chemistry, Ljubljana, Slovenia
| | - Arne Praznik
- Department of Synthetic Biology and Immunology, National Institute of Chemistry, Ljubljana, Slovenia
| | - Roman Jerala
- Department of Synthetic Biology and Immunology, National Institute of Chemistry, Ljubljana, Slovenia
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Mamazhakypov A, Viswanathan G, Lawrie A, Schermuly RT, Rajagopal S. The role of chemokines and chemokine receptors in pulmonary arterial hypertension. Br J Pharmacol 2019; 178:72-89. [PMID: 31399998 DOI: 10.1111/bph.14826] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 07/25/2019] [Accepted: 07/26/2019] [Indexed: 12/11/2022] Open
Abstract
Pulmonary arterial hypertension (PAH) is characterized by progressive pulmonary artery remodelling leading to increased right ventricular pressure overload, which results in right heart failure and premature death. Inflammation plays a central role in the development of PAH, and the recruitment and function of immune cells are tightly regulated by chemotactic cytokines called chemokines. A number of studies have shown that the development and progression of PAH are associated with the dysregulated expression of several chemokines and chemokine receptors in the pulmonary vasculature. Moreover, some chemokines are differentially regulated in the pressure-overloaded right ventricle. Recent studies have tested the efficacy of pharmacological agents targeting several chemokines and chemokine receptors for their effects on the development of PAH, suggesting that these receptors could serve as useful therapeutic targets. In this review, we provide recent insights into the role of chemokines and chemokine receptors in PAH and RV remodelling and the opportunities and roadblocks in targeting them. LINKED ARTICLES: This article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.1/issuetoc.
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Affiliation(s)
- Argen Mamazhakypov
- Department of Internal Medicine, Member of the German Center for Lung Research (DZL), Justus Liebig University of Giessen, Giessen, Germany
| | - Gayathri Viswanathan
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, NC, USA
| | - Allan Lawrie
- Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, UK
| | - Ralph Theo Schermuly
- Department of Internal Medicine, Member of the German Center for Lung Research (DZL), Justus Liebig University of Giessen, Giessen, Germany
| | - Sudarshan Rajagopal
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, NC, USA
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Prakash J, Herlin M, Kumar J, Garg G, Akesson KE, Grabowski PS, Skerry TM, Richards GO, McGuigan FE. Analysis of RAMP3 gene polymorphism with body composition and bone density in young and elderly women. Gene 2019; 721S:100009. [PMID: 32550545 PMCID: PMC7286079 DOI: 10.1016/j.gene.2019.100009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 02/06/2019] [Indexed: 02/07/2023]
Abstract
Background and aim The Receptor Activity Modifying Proteins (RAMPs) are a group of accessory proteins, of which there are three in humans, that interact with a number of G-protein coupled receptors (GPCR) and play various roles in regulation of endocrine signaling. Studies in RAMP3 knockout (KO) mice reveal an age related phenotype with altered metabolic regulation and high bone mass. To translate these findings into a clinically relevant perspective, we investigated the association between RAMP3 gene variants, body composition and bone phenotypes in two population-based cohorts of Swedish women. Methods Five single nucleotide polymorphisms (SNP) in the vicinity of the RAMP3 gene were genotyped in the PEAK-25 cohort (n = 1061; 25 years) and OPRA (n = 1044; 75 years). Bone mineral density (BMD), fat mass and lean mass (total body; regional) were measured by DXA at baseline, 5 and 10 year follow-up. Results BMD did not differ with RAMP3 genotype in either cohort, although fracture risk was increased in the elderly women (OR 2.695 [95% CI 1.514–4.801]). Fat mass tended to be higher with RAMP3 SNPs; although only in elderly women. In the young women, changes in BMI and fat mass between ages 25–35 differed by genotype (p = 0.001; p < 0.001). Conclusion Variation in RAMP3 may contribute to age-related changes in body composition and risk of fracture.
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Key Words
- AM1R, Adrenomedullin-1 Receptor
- AM2R, Adrenomedullin-2 Receptor
- AMY3, Amylin Receptor Complex
- BMD
- BMD, Bone Mineral Density
- CGRP, Calcitonin Gene-Related Peptide
- CLR, Calcitonin Like-Receptor
- FM, Fat Mass
- FN, Femoral Neck
- Fat
- Fracture
- GPCR, G-Protein Coupled Receptor
- KO, Knock-out
- LM, Lean Mass
- LS, Lumbar Spine
- OPRA, Osteoporosis Prospective Risk Assessment
- RAMP3
- RAMP3, Receptor Activity Modifying Protein 3
- SNP
- SNP, Single Nucleotide Polymorphism
- TB, Total Body
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Affiliation(s)
- Jai Prakash
- Lund University, Dept. of Clinical Sciences Malmö, Clinical and Molecular Osteoporosis Research Unit, Sweden
| | - Maria Herlin
- Lund University, Dept. of Clinical Sciences Malmö, Clinical and Molecular Osteoporosis Research Unit, Sweden
- Dept. of Environmental Research and Monitoring, Swedish Museum of Natural History, Stockholm, Sweden
| | - Jitender Kumar
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Noida, India
| | - Gaurav Garg
- Genomics Division, LCGC Life sciences LLP, New Delhi, India
| | - Kristina E. Akesson
- Lund University, Dept. of Clinical Sciences Malmö, Clinical and Molecular Osteoporosis Research Unit, Sweden
- Skåne University Hospital, Dept. of Orthopedics, Malmö, Sweden
| | - Peter S. Grabowski
- Human Nutrition Unit, Dept. of Oncology and Metabolism, Sheffield University, UK
| | - Tim M. Skerry
- Academic Unit of Bone Biology, Dept. of Oncology and Metabolism, Sheffield University, UK
| | - Gareth O. Richards
- Academic Unit of Bone Biology, Dept. of Oncology and Metabolism, Sheffield University, UK
| | - Fiona E.A. McGuigan
- Lund University, Dept. of Clinical Sciences Malmö, Clinical and Molecular Osteoporosis Research Unit, Sweden
- Corresponding author.
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Kumari A, Rekhi L, Datta S. Reversibly Attached Phospholipid Bilayer-Functionalized Membrane Pores. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:14395-14401. [PMID: 30392365 DOI: 10.1021/acs.langmuir.8b03404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report the development of reversibly attached phospholipid bilayer (PLB)-functionalized membrane pores that enabled reusability of the membrane matrix as well as the phospholipid. The functionalized architecture was constructed based on electrostatic interactions, which facilitate the reversible attachment-detachment sequence of the functional moieties within membrane pores. To demonstrate potential application, an enzyme, glucose oxidase (GOx), was electrostatically immobilized within the PLB-functionalized membrane and enzymatic catalysis was conducted under the convective flow mode. The GOx-immobilized membrane demonstrated satisfactory activity and stability. Convective flow of the substrate solution resulted in significantly higher activity than diffusive flow. Then, the enzyme was detached keeping the functional PLB backbone intact. Detachment of the enzyme without affecting the functional activity of PLB backbone permits attachment of fresh enzyme. In addition, reusability of the phospholipids is also of great importance as they have wide range of applications, but their usage is limited by higher cost. We have demonstrated the detachment of the PLB from the membrane using a simple technique. Characterization of the detached phospholipid confirmed retention of the original structural and functional properties as exhibited before attachment. To the best of our knowledge, this is the first study on reversible PLB formation within membrane pores and demonstration of a detachment technique, while maintaining the structural and functional properties of the phospholipid.
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Affiliation(s)
- Anju Kumari
- Department of Biotechnology , Indian Institute of Technology Roorkee , Roorkee 247667 , Uttarakhand , India
| | - Lavie Rekhi
- Department of Biotechnology , Indian Institute of Technology Roorkee , Roorkee 247667 , Uttarakhand , India
| | - Saurav Datta
- Department of Biotechnology , Indian Institute of Technology Roorkee , Roorkee 247667 , Uttarakhand , India
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Gα i3 signaling is associated with sexual dimorphic expression of the clock-controlled output gene Dbp in murine liver. Oncotarget 2018; 9:30213-30224. [PMID: 30100984 PMCID: PMC6084400 DOI: 10.18632/oncotarget.25727] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 06/14/2018] [Indexed: 11/25/2022] Open
Abstract
The albumin D-box binding protein (DBP) is a member of the PAR bZip (proline and acidic amino acid-rich basic leucine zipper) transcription factor family and functions as important regulator of circadian core and output gene expression. Gene expression of DBP itself is under the control of E-box-dependent binding by the Bmal1-Clock heterodimer and CRE-dependent binding by the cAMP responsive element binding protein (CREB). However, the signaling mechanism mediating CREB-dependent regulation of DBP expression in the peripheral clock remains elusive. In this study, we examined the role of the GPCR (G-protein-coupled receptor)/Gαi3 (Galphai3) controlled cAMP-CREB signaling pathway in the regulation of hepatic expression of core clock and clock-regulated genes, including Dbp. Analysis of circadian gene expression revealed that rhythmicity of hepatic transcript levels of the majority of core clock (including Per1) and clock-regulated genes were not affected by Gαi3 deficiency. Consistently, the period length of primary Gαi3 deficient tail fibroblasts expressing a Bmal1-Luciferase reporter was not affected. Interestingly, however, Gαi3 deficient female but not male mice showed a tendentiously increased activation of CREB (nuclear pSer133-CREB) accompanied by an advanced peak in Dbp gene expression and elevated mRNA levels of the cytochrome P450 family member Cyp3a11, a target gene of DBP. Accordingly, selective inhibition of CREB led to a strongly decreased expression of DBP and CYP3A4 (human Cyp3a11 homologue) in HepG2 liver cells. In summary, our data suggest that the Gαi3-pCREB signalling pathway functions as a regulator of sexual-dimorphic expression of DBP and its xenobiotic target enzymes Cyp3a11/CYP3A4.
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7
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Luttrell LM, Maudsley S, Gesty-Palmer D. Translating in vitro ligand bias into in vivo efficacy. Cell Signal 2017; 41:46-55. [PMID: 28495495 DOI: 10.1016/j.cellsig.2017.05.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 05/04/2017] [Indexed: 01/04/2023]
Abstract
It is increasingly apparent that ligand structure influences both the efficiency with which G protein-coupled receptors (GPCRs) engage their downstream effectors and the manner in which they are activated. Thus, 'biased' agonists, synthetic ligands whose intrinsic efficacy differs from the native ligand, afford a strategy for manipulating GPCR signaling in ways that promote beneficial signals while blocking potentially deleterious ones. Still, there are significant challenges in relating in vitro ligand efficacy, which is typically measured in heterologous expression systems, to the biological response in vivo, where the ligand is acting on natively expressed receptors and in the presence of the endogenous ligand. This is particularly true of arrestin pathway-selective 'biased' agonists. The type 1 parathyroid hormone receptor (PTH1R) is a case in point. Parathyroid hormone (PTH) is the principal physiological regulator of calcium homeostasis, and PTH1R expressed on cells of the osteoblast lineage are an established therapeutic target in osteoporosis. In vitro, PTH1R signaling is highly sensitive to ligand structure, and PTH analogs that affect the selectivity/kinetics of G protein coupling or that engage arrestin-dependent signaling mechanisms without activating heterotrimeric G proteins have been identified. In vivo, intermittent administration of conventional PTH analogs accelerates the rate of osteoblastic bone formation, largely through known cAMP-dependent mechanisms. Paradoxically, both intermittent and continuous administration of an arrestin pathway-selective PTH analog, which in vivo would be expected to antagonize endogenous PTH1R-cAMP signaling, also increases bone mass. Transcriptomic analysis of tissue from treated animals suggests that conventional and arrestin pathway-selective PTH1R ligands act in largely different ways, with the latter principally affecting pathways involved in the regulation of cell cycle, survival, and migration/cytoskeletal dynamics. Such multi-dimensional in vitro and in vivo analyses of ligand bias may provide insights into the physiological roles of non-canonical arrestin-mediated signaling pathways in vivo, and provide a conceptual framework for translating arrestin pathway-selective ligands into viable therapeutics.
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Affiliation(s)
- Louis M Luttrell
- Division of Endocrinology, Diabetes & Medical Genetics, Medical University of South Carolina, Charleston, SC 29425, USA; Research Service of the Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC, 29401, USA.
| | - Stuart Maudsley
- Translational Neurobiology Group, VIB Department of Molecular Genetics, Laboratory of Neurogenetics-Institute Born-Bunge, University of Antwerp, Belgium
| | - Diane Gesty-Palmer
- Division of Endocrinology, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
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8
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Cai M, Hruby VJ. Design of cyclized selective melanotropins. Biopolymers 2017; 106:876-883. [PMID: 27561155 DOI: 10.1002/bip.22976] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2016] [Revised: 08/19/2016] [Accepted: 08/22/2016] [Indexed: 01/02/2023]
Abstract
This article describes the development of cyclic peptides for G-protein coupled receptors to enable structure-function knowledge and the design of novel therapeutics. One important property of cyclic peptides is that they tend to be resistant to the digestion, enabling them to survive in the human digestive tract. This trait makes them very important as drug leads or as scaffolds which, in theory, can be engineered to incorporate a peptide domain of medicinal value. This is especially important for delivery of peptides that would be destroyed without such implementation. The melanocortin system is the focus of this article, and includes melanotropin ligands and melanocortin receptors. We examine two strategies to constrain the melanotropin peptide backbone. The first is based on global constraint of peptides by cyclization using various kinds of linkers. In the second approach we describe the use of a natural cyclized template, the cyclotide, to graft the melanotropin phamacophore, -His-Phe-Arg-Trp-, to obtain selective drug leads. In these examples the conserved melanocyte stimulating hormone pharmacophore is examined and the modified peptides were synthesized by solid phase methodology. Biological studies confirmed the production of selective, potent and in some cases orally available ligands.
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Affiliation(s)
- Minying Cai
- Department of Chemistry & Biochemistry, University of Arizona, 1306 E University Blvd, Tucson, AZ, 85721
| | - Victor J Hruby
- Department of Chemistry & Biochemistry, University of Arizona, 1306 E University Blvd, Tucson, AZ, 85721
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9
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Sandhu K, Mamas M, Butler R. Endothelial progenitor cells: Exploring the pleiotropic effects of statins. World J Cardiol 2017; 9:1-13. [PMID: 28163831 PMCID: PMC5253189 DOI: 10.4330/wjc.v9.i1.1] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 08/29/2016] [Accepted: 11/02/2016] [Indexed: 02/07/2023] Open
Abstract
Statins have become a cornerstone of risk modification for ischaemic heart disease patients. A number of studies have shown that they are effective and safe. However studies have observed an early benefit in terms of a reduction in recurrent infarct and or death after a myocardial infarction, prior to any significant change in lipid profile. Therefore, pleiotropic mechanisms, other than lowering lipid profile alone, must account for this effect. One such proposed pleiotropic mechanism is the ability of statins to augment both number and function of endothelial progenitor cells. The ability to augment repair and maintenance of a functioning endothelium may have profound beneficial effect on vascular repair and potentially a positive impact on clinical outcomes in patients with cardiovascular disease. The following literature review will discuss issues surrounding endothelial progenitor cell (EPC) identification, role in vascular repair, factors affecting EPC numbers, the role of statins in current medical practice and their effects on EPC number.
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10
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Kim SK, Goddard III WA. Molecular-Docking-Based Drug Design and Discovery. PHARMACEUTICAL SCIENCES 2017. [DOI: 10.4018/978-1-5225-1762-7.ch025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Currently 30-50% of drug targets are G Protein-Coupled Receptors (GPCRs). However, the clinical useful drugs for targeting GPCR have been limited by the lack of subtype selectivity or efficacy, leading to undesirable side effects. To develop subtype-selective GPCR ligands with desired molecular properties, better understanding is needed of the pharmacophore elements and of the binding mechanism required for subtype selectivity. To illustrate these issues, we describe here three successful applications to understand the binding mechanism associated with subtype selectivity: 5-HT2B (5-Hydroxytryptamine, 5-HT) serotonin receptor (HT2BR), H3 histamine receptor (H3HR) and A3 adenosine receptor (A3AR). The understanding of structure-function relationships among individual types and subtypes of GPCRs gained from such computational predictions combined with experimental validation and testing is expected the development of new highly selective and effective ligands to address such diseases while minimizing side-effects.
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11
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Fuentealba J, Toro-Tapia G, Rodriguez M, Arriagada C, Maureira A, Beyer A, Villaseca S, Leal JI, Hinrichs MV, Olate J, Caprile T, Torrejón M. Expression profiles of the Gα subunits during Xenopus tropicalis embryonic development. Gene Expr Patterns 2016; 22:15-25. [PMID: 27613600 DOI: 10.1016/j.gep.2016.09.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 07/31/2016] [Accepted: 09/04/2016] [Indexed: 10/21/2022]
Abstract
Heterotrimeric G protein signaling plays major roles during different cellular events. However, there is a limited understanding of the molecular mechanisms underlying G protein control during embryogenesis. G proteins are highly conserved and can be grouped into four subfamilies according to sequence homology and function. To further studies on G protein function during embryogenesis, the present analysis identified four Gα subunits representative of the different subfamilies and determined their spatiotemporal expression patterns during Xenopus tropicalis embryogenesis. Each of the Gα subunit transcripts was maternally and zygotically expressed, and, as development progressed, dynamic expression patterns were observed. In the early developmental stages, the Gα subunits were expressed in the animal hemisphere and dorsal marginal zone. While expression was observed at the somite boundaries, in vascular structures, in the eye, and in the otic vesicle during the later stages, expression was mainly found in neural tissues, such as the neural tube and, especially, in the cephalic vesicles, neural crest region, and neural crest-derived structures. Together, these results support the pleiotropism and complexity of G protein subfamily functions in different cellular events. The present study constitutes the most comprehensive description to date of the spatiotemporal expression patterns of Gα subunits during vertebrate development.
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Affiliation(s)
- Jaime Fuentealba
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Gabriela Toro-Tapia
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Marion Rodriguez
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Cecilia Arriagada
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Alejandro Maureira
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Andrea Beyer
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Soraya Villaseca
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Juan I Leal
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Maria V Hinrichs
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Juan Olate
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Teresa Caprile
- Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Marcela Torrejón
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile.
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Tripathy R, Mishra D, Konkimalla VB. A novel fuzzy C-means approach for uncovering cholesterol consensus motif from human G-protein coupled receptors (GPCR). KARBALA INTERNATIONAL JOURNAL OF MODERN SCIENCE 2015. [DOI: 10.1016/j.kijoms.2015.11.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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13
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Jafurulla M, Chattopadhyay A. Sphingolipids in the function of G protein-coupled receptors. Eur J Pharmacol 2015; 763:241-6. [DOI: 10.1016/j.ejphar.2015.07.019] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Revised: 06/01/2015] [Accepted: 07/07/2015] [Indexed: 11/26/2022]
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14
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Meng XY, Mezei M, Cui M. Computational approaches for modeling GPCR dimerization. Curr Pharm Biotechnol 2015; 15:996-1006. [PMID: 25307013 DOI: 10.2174/1389201015666141013102515] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 07/09/2014] [Accepted: 08/18/2014] [Indexed: 11/22/2022]
Abstract
Growing experimental evidences suggest that dimerization and oligomerization are important for G Protein- Coupled Receptors (GPCRs) function. The detailed structural information of dimeric/oligomeric GPCRs would be very important to understand their function. Although it is encouraging that recently several experimental GPCR structures in oligomeric forms have appeared, experimental determination of GPCR structures in oligomeric forms is still a big challenge, especially in mimicking the membrane environment. Therefore, development of computational approaches to predict dimerization of GPCRs will be highly valuable. In this review, we summarize computational approaches that have been developed and used for modeling of GPCR dimerization. In addition, we introduce a novel two-dimensional Brownian Dynamics based protein docking approach, which we have recently adapted, for GPCR dimer prediction.
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Affiliation(s)
| | | | - Meng Cui
- Institute of Quantitative Biology and Medicine, Jiangsu Provincial Key Laboratory of Radiation Medicine and Protection, Soochow University, Suzhou 215123, China.
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15
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Chakraborty H, Chattopadhyay A. Excitements and challenges in GPCR oligomerization: molecular insight from FRET. ACS Chem Neurosci 2015; 6:199-206. [PMID: 25363209 DOI: 10.1021/cn500231d] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are the largest family of proteins involved in signal transduction across cell membranes, and they represent major drug targets in all clinical areas. Oligomerization of GPCRs and its implications in drug discovery constitute an exciting area in contemporary biology. In this Review, we have highlighted the application of fluorescence resonance energy transfer (FRET) in exploring GPCR oligomerization, with special emphasis on possible pitfalls and experimental complications involved. Based on FRET photophysics, we discuss some of the possible complications, and recommend that FRET results in complex cellular environments should be interpreted with caution. Although both hetero- and homo-FRET are used in measurements of GPCR oligomerization, we suggest that homo-FRET enjoys certain advantages over hetero-FRET. Given the seminal role of GPCRs as current drug targets, we envision that methodological progress in studying GPCR oligomerization would result in better therapeutic strategies.
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Affiliation(s)
- Hirak Chakraborty
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
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Chattopadhyay A, Rao BD, Jafurulla M. Solubilization of G Protein-Coupled Receptors. Methods Enzymol 2015; 557:117-34. [DOI: 10.1016/bs.mie.2015.01.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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17
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Abstract
G protein-coupled receptors (GPCRs) are the largest class of molecules involved in signal transduction across cell membranes and represent major targets in the development of novel drug candidates in all clinical areas. Although there have been some recent leads, structural information on GPCRs is relatively rare due to the difficulty associated with crystallization. A specific reason for this is the intrinsic flexibility displayed by GPCRs, which is necessary for their functional diversity. Since GPCRs are integral membrane proteins, interaction of membrane lipids with them constitutes an important area of research in GPCR biology. In particular, membrane cholesterol has been reported to have a modulatory role in the function of a number of GPCRs. The role of membrane cholesterol in GPCR function is discussed with specific example of the serotonin1A receptor. Recent results show that GPCRs are characterized with structural motifs that preferentially associate with cholesterol. An emerging and important concept is oligomerization of GPCRs and its role in GPCR function and signaling. The role of membrane cholesterol in GPCR oligomerization is highlighted. Future research in GPCR biology would offer novel insight in basic biology and provide new avenues for drug discovery.
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Protein kinase inhibitor β enhances the constitutive activity of G-protein-coupled zinc receptor GPR39. Biochem J 2014; 462:125-32. [PMID: 24869658 DOI: 10.1042/bj20131198] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
GPR39 is a G-protein-coupled zinc receptor that protects against diverse effectors of cell death. Its protective activity is mediated via constitutive activation of Gα13 and the RhoA pathway, leading to increased SRE (serum-response element)-dependent transcription; the zinc-dependent immediate activation of GPR39 involves Gq-mediated increases in cytosolic Ca2+ and Gs coupling leading to increased cAMP levels. We used the cytosolic and soluble C-terminus of GPR39 in a Y2H (yeast-2-hybrid) screen for interacting proteins, thus identifying PKIB (protein kinase A inhibitor β). Co-expression of GPR39 with PKIB increased the protective activity of GPR39 via the constitutive, but not the ligand-mediated, pathway. PKIB inhibits protein kinase A by direct interaction with its pseudosubstrate domain; mutation of this domain abolished the inhibitory activity of PKIB on protein kinase A activity, but had no effect on the interaction with GPR39, cell protection and induction of SRE-dependent transcription. Zinc caused dissociation of PKIB from GPR39, thereby liberating it to associate with protein kinase A and inhibit its activity, which would result in a negative-feedback loop with the ability to limit activation of the Gs pathway by zinc.
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Brugarolas M, Navarro G, Martínez-Pinilla E, Angelats E, Casadó V, Lanciego JL, Franco R. G-protein-coupled receptor heteromers as key players in the molecular architecture of the central nervous system. CNS Neurosci Ther 2014; 20:703-9. [PMID: 24809909 DOI: 10.1111/cns.12277] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 04/02/2014] [Accepted: 04/02/2014] [Indexed: 12/16/2022] Open
Abstract
The overall architecture of the nervous system, especially the CNS, is remarkable. The anatomy of the nervous system is constituted not only by macroscopic and microscopy identifiable regions and neuronal cell types, but also by protein complexes whose identification and localization require sophisticated techniques. G-protein-coupled receptors (GPCRs) constitute an example of proteins that are the key factors in the framework needed to sustain brain and nerve structure and function. The versatility underlying nervous system anatomy takes advantage of a recently discovered feature of GPCRs, the possibility to form heteromers that, placed at specific neuronal subsets and at specific locations (pre-, post-, or peri-synaptic), contribute to attain unique neural functions.
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Affiliation(s)
- Marc Brugarolas
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona (UB), Barcelona, Spain; Centro investigación biomédica en red enfermedades neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
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AIP inactivation leads to pituitary tumorigenesis through defective Gαi-cAMP signaling. Oncogene 2014; 34:1174-84. [PMID: 24662816 DOI: 10.1038/onc.2014.50] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Revised: 12/16/2013] [Accepted: 01/01/2014] [Indexed: 01/03/2023]
Abstract
The aryl hydrocarbon receptor interacting protein (AIP) is a tumor-suppressor gene underlying the pituitary adenoma predisposition. Thus far, the exact molecular mechanisms by which inactivated AIP exerts its tumor-promoting action have been unclear. To better understand the role of AIP in pituitary tumorigenesis, we performed gene expression microarray analysis to examine changes between Aip wild-type and knockout mouse embryonic fibroblast (MEF) cell lines. Transcriptional analyses implied that Aip deficiency causes a dysfunction in cyclic adenosine monophosphate (cAMP) signaling, as well as impairments in signaling cascades associated with developmental and immune-inflammatory responses. In vitro experiments showed that AIP deficiency increases intracellular cAMP concentrations in both MEF and murine pituitary adenoma cell lines. Based on knockdown of various G protein α subunits, we concluded that AIP deficiency leads to elevated cAMP concentrations through defective Gαi-2 and Gαi-3 proteins that normally inhibit cAMP synthesis. Furthermore, immunostaining of Gαi-2 revealed that AIP deficiency is associated with a clear reduction in Gαi-2 protein expression levels in human and mouse growth hormone (GH)-secreting pituitary adenomas, thus indicating defective Gαi signaling in these tumors. By contrast, all prolactin-secreting tumors showed prominent Gαi-2 protein levels, irrespective of Aip mutation status. We additionally observed reduced expression of phosphorylated extracellular signal-regulated kinases 1/2 and cAMP response element-binding protein levels in mouse and human AIP-deficient somatotropinomas. This study implies for the first time that a failure to inhibit cAMP synthesis through dysfunctional Gαi signaling underlies the development of GH-secreting pituitary adenomas in AIP mutation carriers.
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Luttrell LM. Minireview: More than just a hammer: ligand "bias" and pharmaceutical discovery. Mol Endocrinol 2014; 28:281-94. [PMID: 24433041 DOI: 10.1210/me.2013-1314] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Conventional orthosteric drug development programs targeting G protein-coupled receptors (GPCRs) have focused on the concepts of agonism and antagonism, in which receptor structure determines the nature of the downstream signal and ligand efficacy determines its intensity. Over the past decade, the emerging paradigms of "pluridimensional efficacy" and "functional selectivity" have revealed that GPCR signaling is not monolithic, and that ligand structure can "bias" signal output by stabilizing active receptor states in different proportions than the native ligand. Biased ligands are novel pharmacologic entities that possess the unique ability to qualitatively change GPCR signaling, in effect creating "new receptors" with distinct efficacy profiles driven by ligand structure. The promise of biased agonism lies in this ability to engender "mixed" effects not attainable using conventional agonists or antagonists, promoting therapeutically beneficial signals while antagonizing deleterious ones. Indeed, arrestin pathway-selective agonists for the type 1 parathyroid hormone and angiotensin AT1 receptors, and G protein pathway-selective agonists for the GPR109A nicotinic acid and μ-opioid receptors, have demonstrated unique, and potentially therapeutic, efficacy in cell-based assays and preclinical animal models. Conversely, activating GPCRs in "unnatural" ways may lead to downstream biological consequences that cannot be predicted from prior knowledge of the actions of the native ligand, especially in the case of ligands that selectively activate as-yet poorly characterized G protein-independent signaling networks mediated via arrestins. Although much needs to be done to realize the clinical potential of functional selectivity, biased GPCR ligands nonetheless appear to be important new additions to the pharmacologic toolbox.
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Affiliation(s)
- Louis M Luttrell
- Department of Medicine and Department of Biochemistry & Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425; and Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401
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Halder S, Kumar S, Sharma R. The therapeutic potential of GPR120: a patent review. Expert Opin Ther Pat 2013; 23:1581-90. [DOI: 10.1517/13543776.2013.842977] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Yamamoto K, Mirabeau O, Bureau C, Blin M, Michon-Coudouel S, Demarque M, Vernier P. Evolution of dopamine receptor genes of the D1 class in vertebrates. Mol Biol Evol 2012. [PMID: 23197594 PMCID: PMC3603308 DOI: 10.1093/molbev/mss268] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The receptors of the dopamine neurotransmitter belong to two unrelated classes named D1 and D2. For the D1 receptor class, only two subtypes are found in mammals, the D1A and D1B, receptors, whereas additional subtypes, named D1C, D1D, and D1X, have been found in other vertebrate species. Here, we analyzed molecular phylogeny, gene synteny, and gene expression pattern of the D1 receptor subtypes in a large range of vertebrate species, which leads us to propose a new view of the evolution of D1 dopamine receptor genes. First, we show that D1C and D1D receptor sequences are encoded by orthologous genes. Second, the previously identified Cypriniform D1X sequence is a teleost-specific paralog of the D1B sequences found in all groups of jawed vertebrates. Third, zebrafish and several sauropsid species possess an additional D1-like gene, which is likely to form another orthology group of vertebrate ancestral genes, which we propose to name D1E. Ancestral jawed vertebrates are thus likely to have possessed four classes of D1 receptor genes—D1A, D1B(X), D1C(D), and D1E—which arose from large-scale gene duplications. The D1C receptor gene would have been secondarily lost in the mammalian lineage, whereas the D1E receptor gene would have been lost independently in several lineages of modern vertebrates. The D1A receptors are well conserved throughout jawed vertebrates, whereas sauropsid D1C receptors have rapidly diverged, to the point that they were misidentified as D1D. The functional significance of the D1C receptor loss is not known. It is possible that the function may have been substituted with D1A or D1B receptors in mammals, following the disappearance of D1C receptors in these species.
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Affiliation(s)
- Kei Yamamoto
- Neurobiology & Development (UPR 3294), Institute of Neurobiology Alfred Fessard, CNRS Gif-sur-Yvette, France
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Subtleties in GPCR drug discovery: a medicinal chemistry perspective. Drug Discov Today 2012; 17:1133-8. [DOI: 10.1016/j.drudis.2012.06.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 05/21/2012] [Accepted: 06/14/2012] [Indexed: 12/26/2022]
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Inhibiting the breakdown of endogenous opioids and cannabinoids to alleviate pain. Nat Rev Drug Discov 2012; 11:292-310. [DOI: 10.1038/nrd3673] [Citation(s) in RCA: 139] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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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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Niebauer RT, Gao ZG, Li B, Wess J, Jacobson KA. Signaling of the Human P2Y(1) Receptor Measured by a Yeast Growth Assay with Comparisons to Assays of Phospholipase C and Calcium Mobilization in 1321N1 Human Astrocytoma Cells. Purinergic Signal 2011; 1:241-7. [PMID: 16467903 PMCID: PMC1350429 DOI: 10.1007/s11302-005-6310-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
The human P2Y(1) receptor was expressed in the yeast Saccharomyces cerevisiae strain MPY578q5, which is engineered to couple to mammalian G protein-coupled receptors (GPCRs) and requires agonist-induced activation for growth. A range of known P2Y(1) receptor agonists were examined with the yeast growth assay system, and the results were validated by comparing with potencies in the transfected 1321N1 astrocytoma cell line, in which calcium mobilization was measured with a FLIPR (fluorescence-imaging plate reader). The data were also compared with those from phospholipase C activation and radioligand binding with the use of a newly available radioligand [H]MRS2279 (2-chloro- N-methyl-(N)-methanocarba-2'-deoxyadenosine-3',5'-bisphosphate). In the yeast growth assay, the rank order of potency of 2-MeSADP (2-methylthioadenosine 5'-diphosphate), ADP (adenosine 5'-diphosphate), and ATP (adenosine 5'-triphosphate) is the same as those in other assay systems, i.e., 2-MeSADP>ADP>ATP. The P2Y(1)-selective antagonist MRS2179 (N-methyl-2-deoxyadenosine-3',5'-bisphosphate) was shown to act as an antagonist with similar potency in all systems. The results suggest that the yeast expression system is suitable for screening P2Y(1) receptor ligands, both agonists and antagonists. The yeast system should be useful for random mutagenesis of GPCRs to identify mutants with certain properties, such as selective potency enhancement for small synthetic molecules and constitutive activity.
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Affiliation(s)
- Ronald T. Niebauer
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0810 USA
- Department of Chemical Engineering, University of Delaware, Newark, Delaware USA
| | - Zhan-Guo Gao
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0810 USA
| | - Bo Li
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland USA
| | - Jürgen Wess
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland USA
| | - Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0810 USA
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Khelashvili G, Mondal S, Andersen OS, Weinstein H. Cholesterol modulates the membrane effects and spatial organization of membrane-penetrating ligands for G-protein coupled receptors. J Phys Chem B 2010; 114:12046-57. [PMID: 20804205 PMCID: PMC2943214 DOI: 10.1021/jp106373r] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The ligands of certain G-protein coupled receptors (GPCRs) are membrane soluble and reach their target from the lipid bilayer. Lipid composition and dynamics will therefore modulate the activity of these receptors, but specific roles of lipid components, including the ubiquitous cholesterol (Chol), are not clear. We have probed the organization and dynamics of such a lipid-bilayer-penetrating ligand, the endogenous ligand for the κ-opioid receptor (KOR) dynorphin A (1-17) (DynA), using molecular dynamics (MD) simulations of DynA in cholesterol-depleted and cholesterol-enriched model membranes. DynA is found to penetrate deep inside fluid dimyristoylphosphatidylcholine (DMPC) bilayers, and resides with its N-terminal helix at ∼6 Å away from the bilayer midplane, in a tilted orientation, at an ∼50° angle with respect to the membrane normal. In contrast, DynA inside DMPC/Chol membranes with 20% cholesterol (DMPC/Chol) is situated with its helical segment ∼5 A higher, i.e., closer to the lipid/water interface and in a relatively vertical orientation. The DMPC membrane shows greater thinning around the insertion and permits a stronger influx of water inside the hydrocarbon core than the DMPC/Chol membranes. Relating these results to data about key GPCR residues that have been implicated in interactions with membrane-inserting GPCR ligands, we conclude that the position of DynA in DMPC/Chol, but not in pure DMPC, correlates with generally proposed GPCR ligand entry pathways. Our predictions provide a possible mechanistic explanation as to why DynA binding to KOR, and the subsequent activation of the receptor, is facilitated in cholesterol-enriched environments. A quantitative description of DynA-induced membrane deformations is obtained with a continuum theory of membrane deformations (CTMD) that is based on hydrophobic matching. Comparison with the MD data reveals the significance of the lipid tail packing energy contribution in the DMPC/Chol mixtures in predicting equilibrium membrane shape around DynA. On this basis, specific corrections are introduced to this energy term within the CTMD framework, thereby extending the applicability of the CTMD framework to lipid raft mixtures and their interactions with GPCR proteins and their ligands.
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Affiliation(s)
- George Khelashvili
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, New York, USA.
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Choi IH, Kim HJ, Jung JH, Nam KY, Yoo SE, Kang NS, No KT. Bayesian Model for the Classification of GPCR Agonists and Antagonists. B KOREAN CHEM SOC 2010. [DOI: 10.5012/bkcs.2010.31.8.2163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Peng ZL, Yang JY, Chen X. An improved classification of G-protein-coupled receptors using sequence-derived features. BMC Bioinformatics 2010; 11:420. [PMID: 20696050 PMCID: PMC3247138 DOI: 10.1186/1471-2105-11-420] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Accepted: 08/09/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND G-protein-coupled receptors (GPCRs) play a key role in diverse physiological processes and are the targets of almost two-thirds of the marketed drugs. The 3 D structures of GPCRs are largely unavailable; however, a large number of GPCR primary sequences are known. To facilitate the identification and characterization of novel receptors, it is therefore very valuable to develop a computational method to accurately predict GPCRs from the protein primary sequences. RESULTS We propose a new method called PCA-GPCR, to predict GPCRs using a comprehensive set of 1497 sequence-derived features. The principal component analysis is first employed to reduce the dimension of the feature space to 32. Then, the resulting 32-dimensional feature vectors are fed into a simple yet powerful classification algorithm, called intimate sorting, to predict GPCRs at five levels. The prediction at the first level determines whether a protein is a GPCR or a non-GPCR. If it is predicted to be a GPCR, then it will be further predicted into certain family, subfamily, sub-subfamily and subtype by the classifiers at the second, third, fourth, and fifth levels, respectively. To train the classifiers applied at five levels, a non-redundant dataset is carefully constructed, which contains 3178, 1589, 4772, 4924, and 2741 protein sequences at the respective levels. Jackknife tests on this training dataset show that the overall accuracies of PCA-GPCR at five levels (from the first to the fifth) can achieve up to 99.5%, 88.8%, 80.47%, 80.3%, and 92.34%, respectively. We further perform predictions on a dataset of 1238 GPCRs at the second level, and on another two datasets of 167 and 566 GPCRs respectively at the fourth level. The overall prediction accuracies of our method are consistently higher than those of the existing methods to be compared. CONCLUSIONS The comprehensive set of 1497 features is believed to be capable of capturing information about amino acid composition, sequence order as well as various physicochemical properties of proteins. Therefore, high accuracies are achieved when predicting GPCRs at all the five levels with our proposed method.
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Affiliation(s)
- Zhen-Ling Peng
- 1Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, T6G 2V4, Canada
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31
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Straßer A, Wittmann HJ. In silico analysis of the histaprodifen induced activation pathway of the guinea-pig histamine H1-receptor. J Comput Aided Mol Des 2010; 24:759-69. [DOI: 10.1007/s10822-010-9372-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Accepted: 06/28/2010] [Indexed: 10/19/2022]
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32
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Zhang JY, Kowal DM, Nawoschik SP, Dunlop J, Pausch MH, Peri R. Development of an improved IP(1) assay for the characterization of 5-HT(2C) receptor ligands. Assay Drug Dev Technol 2010; 8:106-13. [PMID: 19922239 DOI: 10.1089/adt.2009.0205] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The 5-hydroxytryptamine 2C (5-HT(2C)) receptor is a member of the serotonin 5-HT(2) subfamily of G-protein-coupled receptors signaling predominantly via the phospholipase C (PLC) pathway. Stimulation of phosphoinositide (PI) hydrolysis upon 5-HT(2C) receptor activation is traditionally assessed by measuring inositol monophosphate (IP(1)) using time-consuming and labor-intensive anion exchange radioactive assays. In this study, we have developed and optimized a cellular IP(1) assay using homogeneous time-resolved fluorescence (HTRF), a fluorescence resonance energy transfer (FRET)-based technology (Cisbio; Gif sur Yvette, France). The measurement is simple to carry out without the cumbersome steps associated with radioactive assays and may therefore be used as an alternative tool to evaluate PI hydrolysis activated by 5-HT(2C) agonists. In Chinese hamster ovary (CHO) cells stably expressing 5-HT(2C) receptors, characterization of 5-HT(2C) agonists with the HTRF platform revealed a rank order of potency (EC(50), nM) comparable to that from intracellular calcium mobilization studies measured by the fluorometric imaging plate reader (FLIPR). A similar rank order of potency was seen with conventional radioactive PI assay with the exception of 5-HT. Lastly, the new assay data correlated better with agonist-induced calcium responses in FLIPR (R(2) = 0.78) than with values determined by radioactive IP(1) method (R(2) = 0.64). Our study shows that the HTRF FRET-based assay detects IP(1) with good sensitivity and may be streamlined for high-throughput (HTS) applications.
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Affiliation(s)
- Jean Y Zhang
- Department of Neuroscience, Wyeth Research, 865 Ridge Road, Monmouth Junction, NJ 08852, USA.
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Bailey RJ, Bradley JWI, Poyner DR, Rathbone DL, Hay DL. Functional characterization of two human receptor activity-modifying protein 3 variants. Peptides 2010; 31:579-84. [PMID: 20034525 DOI: 10.1016/j.peptides.2009.12.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Revised: 12/10/2009] [Accepted: 12/11/2009] [Indexed: 11/21/2022]
Abstract
Adrenomedullin (AM) and amylin are involved in angiogenesis/lymphangiogenesis and glucose homeostasis/food intake, respectively. They activate receptor activity-modifying protein (RAMP)/G protein-coupled receptor (GPCR) complexes. RAMP3 with the calcitonin receptor-like receptor (CLR) forms the AM(2) receptor, whereas when paired with the calcitonin receptor AMY(3) receptors are formed. RAMP3 interacts with other GPCRs although the consequences of these interactions are poorly understood. Therefore, variations in the RAMP3 sequence, such as single nucleotide polymorphisms or mutations could be relevant to human health. Variants of RAMP3 have been identified. In particular, analysis of AK222469 (Homo sapiens mRNA for receptor (calcitonin) activity-modifying protein 3 precursor variant) revealed several nucleotide differences, three of which encoded amino acid changes (Cys40Trp, Phe100Ser, Leu147Pro). Trp56Arg RAMP3 is a polymorphic variant of human RAMP3 at a conserved amino acid position. To determine their function we used wild-type (WT) human RAMP3 as a template for introducing amino acid mutations. Mutant or WT RAMP3 function was determined in Cos-7 cells with CLR or the calcitonin receptor (CT((a))). Cys40Trp/Phe100Ser/Leu147Pro RAMP3 was functionally compromised, with reduced AM and amylin potency at the respective AM(2) and AMY(3(a)) receptor complexes. Cys40Trp and Phe100Ser mutations contributed to this phenotype, unlike Leu147Pro. Reduced cell-surface expression of mutant receptor complexes probably explains the functional data. In contrast, Trp56Arg RAMP3 was WT in phenotype. This study provides insight into the role of these residues in RAMP3. The existence of AK222469 in the human population has implications for the function of RAMP3/GPCR complexes, particularly AM and amylin receptors.
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Affiliation(s)
- Richard J Bailey
- School of Biological Sciences, University of Auckland, Symonds Street, Auckland, New Zealand.
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de la Fuente T, Martín-Fontecha M, Sallander J, Benhamú B, Campillo M, Medina RA, Pellissier LP, Claeysen S, Dumuis A, Pardo L, López-Rodríguez ML. Benzimidazole derivatives as new serotonin 5-HT6 receptor antagonists. Molecular mechanisms of receptor inactivation. J Med Chem 2010; 53:1357-69. [PMID: 20078106 DOI: 10.1021/jm901672k] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
On the basis of our previously described pharmacophore model for serotonin 5-HT(6) receptor (5-HT(6)R) antagonists, we have designed, synthesized, and pharmacologically characterized a series of benzimidazole derivatives 1-20 that represent a new family of potent antagonists at the human 5-HT(6)R. Site-directed mutagenesis and a beta(2)-adrenoceptor-based homology model of the 5-HT(6)R were used to predict the mode of binding of antagonist SB-258585 and the new synthesized ligands. Substitution of W6.48, F6.52, or N6.55 by Ala fully impedes compound 4 to block 5-HT-induced activation. Thus, we propose that D3.32 in TM 3 anchors the protonated piperazine ring, the benzimidazole ring expands parallel to EL 2 to hydrogen bond N6.55 in TM 6, and the aromatic ring is placed between TMs 3 and 5 in CH(2)-containing compounds and between TMs 3 and 6 in CO-containing compounds. This combined experimental and computational study has permitted to propose the molecular mechanisms by which the new benzimidazole derivatives act as 5-HT(6)R antagonists.
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Affiliation(s)
- Tania de la Fuente
- Departamento de Química Orgánica I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, E-28040 Madrid, Spain
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Paila YD, Chattopadhyay A. Membrane cholesterol in the function and organization of G-protein coupled receptors. Subcell Biochem 2010; 51:439-66. [PMID: 20213554 DOI: 10.1007/978-90-481-8622-8_16] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Cholesterol is an essential component of higher eukaryotic membranes and plays a crucial role in membrane organization, dynamics and function. The G-protein coupled receptors (GPCRs) are the largest class of molecules involved in signal transduction across membranes, and represent major targets in the development of novel drug candidates in all clinical areas. Membrane cholesterol has been reported to have a modulatory role in the function of a number of GPCRs. Two possible mechanisms have been previously suggested by which membrane cholesterol could influence the structure and function of GPCRs (i) through a direct/specific interaction with GPCRs, or (ii) through an indirect way by altering membrane physical properties in which the receptor is embedded, or due to a combination of both. Recently reported crystal structures of GPCRs have shown structural evidence of cholesterol binding sites. Against this backdrop, we recently proposed a novel mechanism by which membrane cholesterol could affect structure and function of GPCRs. According to our hypothesis, cholesterol binding sites in GPCRs could represent 'nonannular' binding sites. Interestingly, previous work from our laboratory has demonstrated that membrane cholesterol is required for the function of the serotonin(1A) receptor (a representative GPCR), which could be due to specific interaction of the receptor with cholesterol. Based on these results, we envisage that there could be specific/nonannular cholesterol binding site(s) in the serotonin(1A) receptor. We have analyzed putative cholesterol binding sites from protein databases in the serotonin(1A) receptor. Our analysis shows that cholesterol binding sites are inherent characteristic features of serotonin(1A) receptors and are conserved through natural evolution. Progress in deciphering molecular details of the GPCR-cholesterol interaction in the membrane would lead to better insight into our overall understanding of GPCR function in health and disease, thereby enhancing our ability to design better therapeutic strategies to combat diseases related to malfunctioning of GPCRs.
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Affiliation(s)
- Yamuna Devi Paila
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Hyderabad, 500 007, India
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Khelashvili G, Grossfield A, Feller SE, Pitman MC, Weinstein H. Structural and dynamic effects of cholesterol at preferred sites of interaction with rhodopsin identified from microsecond length molecular dynamics simulations. Proteins 2009; 76:403-17. [PMID: 19173312 PMCID: PMC4101808 DOI: 10.1002/prot.22355] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
An unresolved question about GPCR function is the role of membrane components in receptor stability and activation. In particular, cholesterol is known to affect the function of membrane proteins, but the details of its effect on GPCRs are still elusive. Here, we describe how cholesterol modulates the behavior of the TM1-TM2-TM7-helix 8(H8) functional network that comprises the highly conserved NPxxY(x)(5,6)F motif, through specific interactions with the receptor. The inferences are based on the analysis of microsecond length molecular dynamics (MD) simulations of rhodopsin in an explicit membrane environment. Three regions on the rhodopsin exhibit the highest cholesterol density throughout the trajectory: the extracellular end of TM7, a location resembling the high-density sterol area from the electron microscopy data; the intracellular parts of TM1, TM2, and TM4, a region suggested as the cholesterol binding site in the recent X-ray crystallography data on beta(2)-adrenergic GPCR; and the intracellular ends of TM2-TM3, a location that was categorized as the high cholesterol density area in multiple independent 100 ns MD simulations of the same system. We found that cholesterol primarily affects specific local perturbations of the helical TM domains such as the kinks in TM1, TM2, and TM7. These local distortions, in turn, relate to rigid-body motions of the TMs in the TM1-TM2-TM7-H8 bundle. The specificity of the effects stems from the nonuniform distribution of cholesterol around the protein. Through correlation analysis we connect local effects of cholesterol on structural perturbations with a regulatory role of cholesterol in the structural rearrangements involved in GPCR function.
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Affiliation(s)
- George Khelashvili
- Department of Physiology and Biophysics, Weill Medical College of Cornell University, New York, New York 10021, USA.
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Albarrán-Juárez J, Gilsbach R, Piekorz RP, Pexa K, Beetz N, Schneider J, Nürnberg B, Birnbaumer L, Hein L. Modulation of alpha2-adrenoceptor functions by heterotrimeric Galphai protein isoforms. J Pharmacol Exp Ther 2009; 331:35-44. [PMID: 19589951 DOI: 10.1124/jpet.109.157230] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Subtype diversity of heterotrimeric G proteins and G protein-coupled receptors enables a wide spectrum of signal transduction. However, the significance of isoforms within receptor or G protein subfamilies has not been fully elucidated. In the present study, we have tested whether alpha(2)-adrenoceptors require specific Galpha isoforms for their function in vivo. In particular, we analyzed the role of the highly homologous Galpha(i) isoforms, Galpha(i1), Galpha(i2), and Galpha(i3), in typical alpha(2)-adrenoceptor-controlled functions. Mice with targeted deletions in the genes encoding Galpha(i1), Galpha(i2), or Galpha(i3) were used to test the effects of alpha(2)-adrenoceptor stimulation by the agonist medetomidine. The alpha(2)-adrenoceptor agonist medetomidine inhibited [(3)H]norepinephrine release from isolated prefrontal brain cortex or cardiac atria tissue specimens with similar potency and efficacy in tissues from wild-type or Galpha(i)-deficient mice. In vivo, bradycardia, hypotension, induction of sleep, antinociception, and hypothermia induced by alpha(2)-adrenoceptor activation did not differ between wild-type and Galpha(i)-knockout mice. However, the effects of the alpha(2)-agonists medetomidine or 5-bromo-6-(2-imidazolin-2-ylamino)quin-oxaline tartrate (UK14,304) on spontaneous locomotor activity or anesthetic sparing were reduced or absent, respectively, in mice lacking Galpha(i2). In microdissected locus coeruleus neurons or postganglionic sympathetic neurons from stellate ganglia, all three Galpha(i) subunits were expressed as determined by quantitative reverse transcription-polymerase chain reaction, with Galpha(i1) and Galpha(i2) dominating over Galpha(i3). Functional redundancy of the highly homologous Galpha(i) isoforms may predominate over specificity to regulate distinct intracellular pathways downstream of alpha(2)-adrenoceptors in vivo. In contrast, inhibition of locomotor activity and anesthetic sparing may be elicited by a specific coupling of alpha(2A)-adrenoceptors via the Galpha(i2) isoform to intracellular pathways.
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Affiliation(s)
- Julián Albarrán-Juárez
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Germany
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Are specific nonannular cholesterol binding sites present in G-protein coupled receptors? BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:295-302. [DOI: 10.1016/j.bbamem.2008.11.020] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2008] [Revised: 11/18/2008] [Accepted: 11/20/2008] [Indexed: 11/23/2022]
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Modulating receptor function through RAMPs: can they represent drug targets in themselves? Drug Discov Today 2009; 14:413-9. [PMID: 19150656 DOI: 10.1016/j.drudis.2008.12.009] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Revised: 12/15/2008] [Accepted: 12/16/2008] [Indexed: 11/21/2022]
Abstract
G protein-coupled receptors (GPCRs) are successfully exploited as drug targets. As our understanding of how distinct GPCR subtypes can be generated expands, so do possibilities for therapeutic intervention via these receptors. Receptor activity-modifying proteins (RAMPs) are excellent examples of proteins that enhance diversity in GPCR function. They facilitate the creation of binding pockets, controlling the pharmacology of some GPCRs. Moreover, they have the ability to regulate cell-surface trafficking, internalisation and signalling of GPCRs, creating novel opportunities for drug discovery. RAMPs could be directly targeted by drugs, or advantage could be taken of unique RAMP/GPCR interfaces for generating highly selective ligands.
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Paila YD, Chattopadhyay A. The function of G-protein coupled receptors and membrane cholesterol: specific or general interaction? Glycoconj J 2008; 26:711-20. [DOI: 10.1007/s10719-008-9218-5] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Revised: 10/29/2008] [Accepted: 11/07/2008] [Indexed: 01/21/2023]
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Deng Y, Wang Y, Holtz B, Li J, Traaseth N, Veglia G, Stottrup BJ, Elde R, Pei D, Guo A, Zhu XY. Fluidic and air-stable supported lipid bilayer and cell-mimicking microarrays. J Am Chem Soc 2008; 130:6267-71. [PMID: 18407640 PMCID: PMC2699764 DOI: 10.1021/ja800049f] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
As drug delivery, therapy, and medical imaging are becoming increasingly cell-specific, there is a critical need for high fidelity and high-throughput screening methods for cell surface interactions. Cell membrane-mimicking surfaces, i.e., supported lipid bilayers (SLBs), are currently not sufficiently robust to meet this need. Here we describe a method of forming fluidic and air-stable SLBs through tethered and dispersed cholesterol groups incorporated into the bottom leaflet. Achieving air stability allows us to easily fabricate SLB microarrays from direct robotic spotting of vesicle solutions. We demonstrate their application as cell membrane-mimicking microarrays by reconstituting peripheral as well as integral membrane components that can be recognized by their respective targets. These demonstrations establish the viability of the fluidic and air-stable SLB platform for generating content microarrays in high throughput studies, e.g., the screening of drugs and nanomedicine targeting cell surface receptors.
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Maurice P, Daulat AM, Broussard C, Mozo J, Clary G, Hotellier F, Chafey P, Guillaume JL, Ferry G, Boutin JA, Delagrange P, Camoin L, Jockers R. A generic approach for the purification of signaling complexes that specifically interact with the carboxyl-terminal domain of G protein-coupled receptors. Mol Cell Proteomics 2008; 7:1556-69. [PMID: 18448421 DOI: 10.1074/mcp.m700435-mcp200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
G protein-coupled receptors (GPCRs) constitute the largest family of membrane receptors and are major drug targets. Recent progress has shown that GPCRs are part of large protein complexes that regulate their activity. We present here a generic approach for identification of these complexes that is based on the use of receptor subdomains and that overcomes the limitations of currently used genetics and proteomics approaches. Our approach consists of a carefully balanced combination of chemically synthesized His6-tagged baits, immobilized metal affinity chromatography, one- and two-dimensional gel electrophoresis separation and mass spectrometric identification. The carboxyl-terminal tails (C-tails) of the human MT1 and MT2 melatonin receptors, two class A GPCRs, were used as models to purify protein complexes from mouse brain lysates. We identified 32 proteins that interacted with the C-tail of MT1, 14 proteins that interacted with the C-tail of MT2, and eight proteins that interacted with both C-tails. Several randomly selected proteins were validated by Western blotting, and the functional relevance of our data was further confirmed by showing the interaction between the full-length MT1 and the regulator of G protein signaling Z1 in transfected HEK 293 cells and native tissue. Taken together, we have established an integrated and generic purification strategy for the identification of high quality and functionally relevant GPCR-associated protein complexes that significantly widens the repertoire of available techniques.
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Affiliation(s)
- Pascal Maurice
- Department of Cell Biology, Institut Cochin, Université Paris Descartes, CNRS (UMR 8104), Paris F-75014, France
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Zhu T, Fang LY, Xie X. Development of a universal high-throughput calcium assay for G-protein- coupled receptors with promiscuous G-protein Galpha15/16. Acta Pharmacol Sin 2008; 29:507-16. [PMID: 18358098 DOI: 10.1111/j.1745-7254.2008.00775.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
AIM To develop a universal high-throughput screening assay based on Galpha15/16- mediated calcium mobilization for the identification of novel modulators of Gprotein- coupled receptors (GPCR). METHODS In the present study, CHO-K1 or HEK293 cells were co-transfected with plasmids encoding promiscuous G-protein Galpha15/16 and various receptors originally coupled to Galphas, Galphai, or Galphaq pathways. Intracellular calcium change was monitored with fluorescent dye Fluo-4. RESULTS We found out for all the receptors tested, Galpha15/16 could shift the receptorso coupling to the calcium mobilization pathway, and the EC50 values of the ligands generated with this method were comparable with reported values that were obtained using traditional methods. This assay was validated and optimized with the zeta-opioid receptor, which originally coupled to Galphai and was recently found to play important roles in neurodegenerative and autoimmune diseases. A largescale screening of 48 000 compounds was performed based on this system. Several new modulators were identified and confirmed with the traditional GTPgammaS binding assay. CONCLUSION This cell-based calcium assay was proved to be robust and easy to automate, and could be used as a universal method in searching for GPCR modulators.
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Affiliation(s)
- Ting Zhu
- The National Center for Drug Screening, Chinese Academy of Sciences, Shanghai 201203, China
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Bhattacharya S, Hall SE, Li H, Vaidehi N. Ligand-stabilized conformational states of human beta(2) adrenergic receptor: insight into G-protein-coupled receptor activation. Biophys J 2008; 94:2027-42. [PMID: 18065472 PMCID: PMC2257890 DOI: 10.1529/biophysj.107.117648] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2007] [Accepted: 11/12/2007] [Indexed: 11/18/2022] Open
Abstract
G-protein-coupled receptors (GPCRs) are known to exist in dynamic equilibrium between inactive- and several active-state conformations, even in the absence of a ligand. Recent experimental studies on the beta(2) adrenergic receptor (beta(2)AR) indicate that structurally different ligands with varying efficacies trigger distinct conformational changes and stabilize different receptor conformations. We have developed a computational method to study the ligand-induced rotational orientation changes in the transmembrane helices of GPCRs. This method involves a systematic spanning of the rotational orientation of the transmembrane helices (TMs) that are in the vicinity of the ligand for predicting the helical rotations that occur on ligand binding. The predicted ligand-stabilized receptor conformations are characterized by a simultaneous lowering of the ligand binding energy and a significant gain in interhelical and receptor-ligand hydrogen bonds. Using the beta(2)AR as a model, we show that the receptor conformational state depends on the structure and efficacy of the ligand for a given signaling pathway. We have studied the ligand-stabilized receptor conformations of five different ligands, a full agonist, norepinephrine; a partial agonist, salbutamol; a weak partial agonist, dopamine; a very weak agonist, catechol; and an inverse agonist, ICI-115881. The predicted ligand-stabilized receptor models correlate well with the experimentally observed conformational switches in beta(2)AR, namely, the breaking of the ionic lock between R131(3.50) at the intracellular end of TM3 (part of the DRY motif) and E268(6.30) on TM6, and the rotamer toggle switch on W286(6.48) on TM6. In agreement with trp-bimane quenching experiments, we found that norepinephrine and dopamine break the ionic lock and engage the rotamer toggle switch, whereas salbutamol, a noncatechol partial agonist only breaks the ionic lock, and the weak agonist catechol only engages the rotamer toggle switch. Norepinephrine and dopamine occupy the same binding region, between TM3, TM5, and TM6, whereas the binding site of salbutamol is shifted toward TM4. Catechol binds deeper into the protein cavity compared to the other ligands, making contact with TM5 and TM6. A part of the catechol binding site overlaps with those of dopamine and norepinephrine but not with that of salbutamol. Virtual ligand screening on 10,060 ligands on the norepinephrine-stabilized receptor conformation shows an enrichment of 38% compared to ligand unbound receptor conformation. These results show that ligand-induced conformational changes are important for developing functionally specific drugs that will stabilize a particular receptor conformation. These studies represent the first step toward a more universally applicable computational method for studying ligand efficacy and GPCR activation.
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Affiliation(s)
- Supriyo Bhattacharya
- Division of Immunology, Beckman Research Institute of the City of Hope, Duarte, California 91010, USA
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Kalipatnapu S, Chattopadhyay A. Membrane Organization and Function of the Serotonin1A Receptor. Cell Mol Neurobiol 2007; 27:1097-116. [PMID: 17710529 DOI: 10.1007/s10571-007-9189-2] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Accepted: 07/27/2007] [Indexed: 01/02/2023]
Abstract
(1) The serotonin(1A) receptor is a G-protein coupled receptor involved in several cognitive, behavioral, and developmental functions. It binds the neurotransmitter serotonin and signals across the membrane through its interactions with heterotrimeric G-proteins. (2) Lipid-protein interactions in membranes play an important role in the assembly, stability, and function of membrane proteins. The role of membrane environment in serotonin(1A) receptor function is beginning to be addressed by exploring the consequences of lipid manipulations on the ligand binding and G-protein coupling of serotonin(1A) receptors, the ability to functionally solubilize the serotonin(1A) receptor, and the factors influencing the membrane organization of the serotonin(1A) receptor. (3) Recent developments involving the application of detergent-based and detergent-free approaches to understand the membrane organization of the serotonin(1A) receptor under conditions of ligand activation and modulation of membrane lipid content, with an emphasis on membrane cholesterol, are described.
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Affiliation(s)
- Shanti Kalipatnapu
- Divisionof Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0377, USA
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Kumar M, Hsiao K, Vidugiriene J, Goueli SA. A bioluminescent-based, HTS-compatible assay to monitor G-protein-coupled receptor modulation of cellular cyclic AMP. Assay Drug Dev Technol 2007; 5:237-45. [PMID: 17477832 DOI: 10.1089/adt.2006.055] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We have developed a novel assay for monitoring changes in intracellular cyclic AMP (cAMP) concentration with high sensitivity (30 +/- 5 fmol [mean +/- standard error of the mean] of cAMP per well) and reproducibility (Z' of > 0.8). The assay is of format amenable to high throughput screening (HTS) in 96-, 384-, and 1,536-well plates, and as a bioluminescent assay is potentially less prone to interferences originating from fluorescent compounds. Because of its high sensitivity, fewer numbers of cells (1,000 cells per well) in low-volume 384-well plates are required to screen for changes in cAMP concentrations. The assay does not rely on the use of antibodies, and thus it does not suffer from changes in the affinity or quality of the antibodies. The assay is based on the fact that cAMP is a potent activator of cAMP-dependent protein kinase (PKA), and activation of PKA can be monitored by measuring ATP utilization in a kinase reaction. The amount of ATP consumed can be measured using a luciferase/luciferin luminescent reaction. Since the amount of relative luminescence units (RLU) generated is a measure of the remaining ATP, a reciprocal relationship between RLU and both the activity of PKA and the intracellular concentration of cAMP is observed. Thus, the functional activity of agents that modulate the activity of Galpha(s) or Galpha(i) forms of G-protein-coupled receptors (GPCRs), which cause change in intracellular cAMP, can be monitored by the change in the activity of PKA and the amount of RLU readout. The assay can be performed in two steps and requires only 30 min after cell lysis for completion. The assay has been successfully used to generate 50% effective concentration (EC(50)) values for forskolin, a known direct activator of cellular adenylate cyclases, and EC(50) values for agonists and 50% inhibitory concentration values for antagonists modulating GPCRs that alter adenylate cyclase activity (Galpha(s) and Galpha(i)). Finally, adherent, suspension, and frozen cells have been successfully used in this assay, thus offering flexibility and convenience for many HTS applications.
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Affiliation(s)
- Meera Kumar
- Research and Development, Promega Corp., Madison, WI 53711, USA
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Kalipatnapu S, Chattopadhyay A, Pucadyil T. Membrane Organization and Dynamics of the Serotonin 1A Receptor Monitored Using Fluorescence Microscopic Approaches. Front Neurosci 2007. [DOI: 10.1201/9781420005752.ch3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Insel PA, Tang CM, Hahntow I, Michel MC. Impact of GPCRs in clinical medicine: monogenic diseases, genetic variants and drug targets. BIOCHIMICA ET BIOPHYSICA ACTA 2007; 1768:994-1005. [PMID: 17081496 PMCID: PMC2169201 DOI: 10.1016/j.bbamem.2006.09.029] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2006] [Revised: 09/28/2006] [Accepted: 09/29/2006] [Indexed: 12/15/2022]
Abstract
By virtue of their large number, widespread distribution and important roles in cell physiology and biochemistry, G-protein-coupled receptors (GPCR) play multiple important roles in clinical medicine. Here, we focus on 3 areas that subsume much of the recent work in this aspect of GPCR biology: (1) monogenic diseases of GPCR; (2) genetic variants of GPCR; and (3) clinically useful pharmacological agonists and antagonists of GPCR. Diseases involving mutations of GPCR are rare, occurring in <1/1000 people, but disorders in which antibodies are directed against GPCR are more common. Genetic variants, especially single nucleotide polymorphisms (SNPs), show substantial heterogeneity in frequency among different GPCRs but have not been evaluated for some GPCR. Many therapeutic agonists and antagonists target GPCR and show inter-subject variability in terms of efficacy and toxicity. For most of those agents, it remains an open question whether genetic variation in primary sequence of the GPCR is an important contributor to such inter-subject variability, although this is an active area of investigation.
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Affiliation(s)
- Paul A Insel
- University of California San diego, Department of Pharmacology, La Jolla, CA 92093-0636, USA.
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Gloro R, Ducrotte P, Reimund JM. Protease-activated receptors: potential therapeutic targets in irritable bowel syndrome? Expert Opin Ther Targets 2007; 9:1079-95. [PMID: 16185159 DOI: 10.1517/14728222.9.5.1079] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Protease-activated receptors (PARs) are a family of four G-protein-coupled receptors (PAR-1 to PAR-4) activated by the proteolytic cleavage of their N-terminal extracellular domain. This activation first involves the recognition of the extracellular domain by proteases, such as thrombin, but also trypsin or tryptase which are particularly abundant in the gastrointestinal tract, both under physiological circumstances and in several digestive diseases. Activation of PARs, particularly of PAR-1 and -2, modulates intestinal functions, such as gastrointestinal motility, visceral nociception, mucosal inflammatory response, and epithelial functions (intestinal secretion and permeability). As these physiological properties have been shown to be altered in various extents and combinations in different clinical presentations of irritable bowel syndrome, PARs appear as putative targets for future therapeutic intervention in these patients.
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Affiliation(s)
- Romain Gloro
- Centre Hospitalier Universitaire de Caen, Service d'Hépato-Gastro-Entérologie et Nutrition, Avenue de la Côte de Nacre, 14033 Caen Cedex, France
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50
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Strosberg AD, Nahmias C. G-protein-coupled receptor signalling through protein networks. Biochem Soc Trans 2007; 35:23-7. [PMID: 17212582 DOI: 10.1042/bst0350023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
This short review provides a broad, and therefore necessarily incomplete and personal, overview of G-protein-coupled receptors, which are often targets for a wide range of important drugs: I will discuss successively their structure, function and interactions with associated proteins. Examples will be drawn from work done over the last 30 years by scientists that worked at different times in my laboratories, mainly in the field of β-adrenoceptors, muscarinic acetylcholine, melatonin and angiotensin receptors.
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Affiliation(s)
- A D Strosberg
- Department of Infectology, The Scripps Research Institute, Jupiter, FL 33458, USA.
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