Date of Award
Ph.D. in Pharmaceutical Sciences
Robert J. Doerksen
David A. Colby
The cannabinoid receptor 1 (CB1) is a class A G-protein coupled receptor that is implicated in a variety of physiological processes, such as energy homeostasis, appetite regulation, cognition and motor control, and mood regulation. CB1 is widely distributed throughout the body, but is mainly expressed in the brain. Molecules that reduce CB1 signaling exhibit anti-obesity properties due to their effect in reducing appetite and body weight gain. However, the consequence of reducing CB1 signaling in the CNS includes adverse neuropsychiatric effects such as depression and suicidal ideation. Two methods of scientific interest for developing CB1 antagonists as anti-obesity drugs are the design of peripherally-restricted antagonists and of negative allosteric modulators of CB1. In this dissertation, we employ molecular modeling tools to explore structural properties of the CB1 receptor and ligands required to generate CB1–ligand complexes in a non-active functional state that have low chances of inducing the adverse CNS-mediated effects.First, we provide a review of different molecular modeling techniques that have been applied in investigating CB1 and its ligands. Next, we generated a 3D-QSAR model based on peripherally-restricted CB1 antagonists. We applied the model and molecular docking in a hybrid virtual screening protocol to identify novel ligands predicted to serve as peripherally-restricted CB1 antagonists. In subsequent in vitro cannabinoid assays, we identified 30 molecules that exhibited CB1 antagonism with micromolar range efficacy. We also investigated plausible allosteric binding sites on CB1 for the well-known negative allosteric modulator, ORG27569, within a CB1–CP55940–ORG27569 ternary complex. Various allosteric binding sites were identified and the top sites were ranked based on the computed energetics of ORG27569 when positioned in those sites. Finally, we studied the seven available experimental 3D structures of CB1 to identify geometric descriptors that are consistent within the three functional states to which the GPCR can belong—active, inactive and intermediate. We identified eleven C?–C? distances that were suitable for distinguishing between the functional states. Our findings provide novel ligands that may be further optimized into peripherally-restricted CB1 antagonists, as well as structural insights into the conformations of CB1 complexes containing a negative allosteric modulator.
Aderibigbe, Ayooluwa Olufunmi, "Computational Modeling of Non-active Functional States of the Cannabinoid Receptor 1 and its Ligands" (2021). Electronic Theses and Dissertations. 2082.
Available for download on Thursday, December 14, 2023