Discovery of new selective antagonists of G-protein coupled receptors of therapeutic interest
GPCR are integral membrane receptor proteins that are characterized by heptahelical transmembrane domains connected by intracellular and extracellular loops. GPCRs are an attractive class of proteins for drug discovery, with more than 50% of all drugs regulating GPCR function, and some 30% of these...
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| Tipo de recurso: | tesis doctoral |
| Fecha de publicación: | 2016 |
| País: | España |
| Institución: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/109356 |
| Acceso en línea: | https://hdl.handle.net/2117/109356 https://dx.doi.org/10.5821/dissertation-2117-109356 |
| Access Level: | acceso abierto |
| Palabra clave: | Àrees temàtiques de la UPC::Enginyeria agroalimentària |
| Sumario: | GPCR are integral membrane receptor proteins that are characterized by heptahelical transmembrane domains connected by intracellular and extracellular loops. GPCRs are an attractive class of proteins for drug discovery, with more than 50% of all drugs regulating GPCR function, and some 30% of these drugs directly target GPCRs. Despite the number of GPCR crystal structures determined recently, they only represent a small fraction of total number of GPCRs known. Homology modelling has been the methodology used to fill the gap. However, the low sequence similarity between targets and templates hampers these studies. Aimed at overcoming these drawbacks template selection and the refinement process were studied in this work. Thus, several atomistic models of rat M3 muscarinic receptor were constructed from human M2 muscarinic receptor, human histamine 1 receptor and bovine rhodopsin receptor as templates. Moreover, in order to determine the effect of ligand in the simulation system, an extra model of M2 receptor was refined with NMS bound inside and an extra model refined without ligand. Results show the sampling time 500ns is adequate simulation time and molecular dynamics simulation of the protein embedded in a lipid bilayer as a refinement process improves on the homology models. Specifically, the refinement process can correct the length of the TM segment of the target receptor; the accuracy of the model greatly depends on the proximity of the template and the target in the phylogenetic tree and finally, the presence of a ligand produces a faster equilibration of the system. This methodology was used to study the pharmacological profile of bradykinin receptors B1 and B2. The B1 receptor was constructed using the chemokine CXC4 and bovine rhodopsin receptors as templates. Antagonists selected for the docking studies include Compound 11, Compound 12, Chroman28, SSR240612, NPV-SAA164 and PS020990. Analysis of the ligand-receptor complexes permitted the definition of a pharmacophore that describes the stereochemical requirements of antagonist binding. For the B2 receptor, a similar procedure was followed using the same template. In this case, the set of compounds used were Fasitibant, FR173657, Anatibant, WIN64338, Bradyzide, CHEMBL442294, and JSM10292. The outcome of this study is summarized in a 3D pharmacophore that explains the observed structure-activity results and provides insight into the design of novel molecules with antagonistic profile. To prove the validity of the pharmacophoric hypotheses, a virtual screening process was carried out. The results of the binding studies show about a 33% success rate with a correlation between the number of pharmacophore points fulfilled and their antagonistic potency. Some of these structures are disclosed in this thesis. Moreover, the B1R and B2R pharmacophores developed were compared and the observed differences permitted to explain the stereochemical requirements for receptor-selective ligands. The final study of this study was to establish a rational explanation for the role of zinc in preventing the dimerization of the serotonin 5-Hydroxytryptamine 1A receptor (5-HT1A) and Galanin receptor 1 (GALR1) involved in depression. Homology modeling was used to build atomistic models of these receptors using the crystallographic structures of 5-HT1B and κ– opioid receptor, respectively. First, prospective zinc binding sites were identified for the 5-HT1A using a molecular probe. Second, heterodimers of the two receptors were constructed with different interfaces: TM4 and TM5; TM6 and TM7; TM1 and TM2. Analysis of the 12 zinc-binding sites and the heterodimer interfaces suggests that there is a coincidence between zinc binding sites and heterodimerization interfaces providing a rational explanation for the role of zinc in the molecular processes associated with heterodimer prevention |
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