Opportunities and challenges for drug discovery in modulating Adhesion G protein-coupled receptor (GPCR) functions

The G protein-coupled receptors (GPCR) superfamily is among the most widely exploited targets for therapeutics, with drugs mainly targeting the Rhodopsin, Glutamate and Secretin family receptors. The receptors of the Adhesion family, however, remain comparatively unexplored in this aspect. This review aims to discuss the druggability of Adhesion GPCRs (aGPCR), highlighting the relevant opportunities and challenges. In this review, the authors provide a disease-oriented summary of aGPCR involvement in humans and discuss the current status of characterizing therapeutic agents with a focus on new opportunities using low molecular weight substances. The small molecule antagonist dihydromunduletone and partial agonist 3-α-acetoxydihydrodeoxygedunin, along with the endogenous natural ligand synaptamide currently comprise some of the most important discoveries made in an attempt to characterize aGPCR druggability. The small molecule modulators provide important insights regarding the structure-activity relationship and suggest that targeting the tethered peptide agonist results in a nonselective pharmacological action, while synaptamide may be considered a potentially attractive tool to achieve a higher degree of selectivity.