The central focus of this Multi-PI R01 research proposal is the structure-function characterization of the human cannabinoid receptor 2 (CB2), a key protein component of the endocannabinoid system.
We aim to develop a fundamental understanding of the structural basis of CB2 function, with the ultimate translational goal of establishing a robust structure-based drug design (SBDD) program. The ECS is a complex network of lipid ligands, receptors, and metabolic enzymes involved in a wide range of important physiological processes. There have been important implications that targeting CB2 may be useful as a means for treating inflammation, pain, neurological disorders and addiction. As with other G protein-coupled receptors (GPCRs), CB2 can exhibit preferential signaling events in response to different ligands. This functional selectivity offers the opportunity to refine therapeutic approaches, to improve beneficial properties, and reduce side effect liability. The study will provide the structural basis for the design and development of pharmacologically distinct CB2-selective compounds as useful biological probes and/or leads for the future development of therapeutics. To enhance our effort in obtaining high quality crystal structures, we shall use carefully designed ligands with high affinities and selectivities for CB2, and which are also capable of tight attachment at or near the receptor?s binding domain(s) coupled with their abilities to form crystallizable ligand-receptor complexes. The study has three specific aims: (1) Design and synthesize novel irreversible ligands representing key classes of CB2 selective compounds with distinct functional profiles. (2) Extensive characterization of the newly synthesized ligands in order to identify compounds with pharmacologically diverse profiles, including the partial agonists, inverse agonists, neutral antagonists and allosteric modulators. The crystallization candidates and their chemical derivatives will also be characterized for their reversible binding nature using functional assays. (3) Develop a clear understanding of CB2 ligand binding sites by determining the 3-D structures of the several receptor-ligand complexes. Towards these goals, several crystal structures will be solved to better understand molecular recognition, signaling, and to assist in the design of novel compounds that could then serve as prototypes for later generation leads and drug candidates.

Public Health Relevance

The study will provide the structural basis for the design and development of pharmacologically distinct CB2- selective compounds as useful biological probes and/or leads for the future development of therapeutics. Results from the proposed work will reveal functionally distinct signaling profiles for the novel compounds that have been designed to facilitate crystallization of the CB2. The detailed comparison of structure and function of the two closely related CB1 and CB2 receptors will facilitate establish a platform for designing highly selective ligands with desired pharmacological profiles and will also provide iterative insight towards introducing pharmacological diversity into probe development.

National Institute of Health (NIH)
National Institute on Drug Abuse (NIDA)
Research Project (R01)
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Molecular Neuropharmacology and Signaling Study Section (MNPS)
Program Officer
Rapaka, Rao
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Northeastern University
Schools of Pharmacy
United States
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Mallipeddi, Srikrishnan; Janero, David R; Zvonok, Nikolai et al. (2017) Functional selectivity at G-protein coupled receptors: Advancing cannabinoid receptors as drug targets. Biochem Pharmacol 128:1-11
Hua, Tian; Vemuri, Kiran; Nikas, Spyros P et al. (2017) Crystal structures of agonist-bound human cannabinoid receptor CB1. Nature 547:468-471
Hua, Tian; Vemuri, Kiran; Pu, Mengchen et al. (2016) Crystal Structure of the Human Cannabinoid Receptor CB1. Cell 167:750-762.e14