Ligand binding to G protein-coupled receptors (GPCRs) 1. 1,8-naphthyridine analogs binding to the cannabinoid CB2 receptor 2. Pharmacophore model development for aminoalkylindole binding to a novel GPCR

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Lyle Lawrence (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site:
Patrica Reggio

Abstract: G-protein coupled receptors (GPCRs) are transmembrane receptors found in eukaryotes that control many cellular signaling events. The cannabinoid receptors, CB1 and CB2, are both GPCRs. These are the receptors that are activated by Δ9-THC, the principal psychoactive compound in marijuana. CB1 is found mainly in neuronal cells and its activation is thought to lead to the negative, psychoactive side effects of marijuana. CB2 is found in immune cells and in small concentrations in brain tissue. Beneficial effects of activating the cannabinoid receptors include reduction in intraocular pressure, analgesia, antiemesis, and effects on bone density. Designing a drug that can selectively activate CB2, without activating CB1 should lead to analgesia without the negative side effects of CB1. Recent studies have shown the potential of CB2 in treating neurodegenerative diseases such as Parkinson's and Alzheimer's; increasing the importance for developing CB2 selective drugs. Analogs were developed using the 1,8-naphthyridine scaffold that are selective for CB2. These analogs had different activities at CB2 based on their structures. One goal of my thesis project was to develop a model for the binding of 1,8-naphthyridine analogs binding at CB2 and to develop a hypothesis concerning the structural requirements for their production of agonism or antagonism at CB2. The analogs were synthesized and tested by our collaborator, Dr. Clementina Manera at the University of Pisa. Computational modeling techniques were used to generate conformations of the 1,8-naphthyridine compounds. An automated docking program, Glide, was used to generate the ligand-receptor complexes. The model showed that the presence of a substituent at the C-6 position of the 1,8-naphthyridine ring prevents CB2 from adopting an activated state. Project 2. Aminoalkylindole Pharmacophore Model A second goal of my thesis was to develop a pharmacophore model for the newly discovered aminoalkylindole (AAI) receptor. WIN 55212-2 is the prototypical aminoalkylindole (AAI) and is known to act as an agonist at both CB1 and CB2. Recently, our collaborator, Dr. Nephi Stella (University of Washington) discovered that WIN 55212-2 and other AAI compounds bind to a non-CB GPCR found in HEK 293 and T98G cells. AAI analogs were developed to generate a structure activity relationship (SAR). These analogs and their binding data were used to generate a pharmacophore model that explains how these AAI compounds are binding to this new receptor. A pharmacophore model is a set of chemical features and their spatial arrangement that explains how a set of compounds bind to a protein. Computational modeling techniques were used to generate conformations of the AAI compounds. The pharmacophore model was developed in PHASE (Schrodinger, Inc.) using a conformational approach on a set of active compounds. The pharmacophore model shows the importance of four aromatic features, a hydrogen bond acceptor feature, and a hydrophobic feature corresponding to the C-2 position of the indole ring.

Additional Information

Language: English
Date: 2014
1,8-Naphthyridine, Aminoalkylindoles, Cannabinoid Receptor, Pharmacophore
G proteins $x Receptors
Ligands (Biochemistry)

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