New Paradigms in GPCR Drug Discovery : Structure Prediction and Design of Ligands with Tailored Properties

G protein-coupled receptors (GPCRs) constitute a large superfamily of membrane proteins with key roles in cellular signaling. Upon activation by a ligand, GPCRs transduce signals from the extracellular to the intracellular environment. GPCRs are important drug targets and are associated with diseases such as central nervous system (CNS) disorders, cardiovascular diseases, cancer, and diabetes. Currently, 34% of FDA-approved drugs mediate their effects via modulation of GPCRs. Research during the past decades has resulted in a deeper understanding of GPCR structure and function. Moreover, recent breakthroughs in structural biology allowed the determination of several atomic resolution GPCR structures. New paradigms in GPCR pharmacology have also emerged that can lead to improved drugs. Together, these advances provide new avenues for structure-based drug discovery. The work in this thesis focused on how the large amount of structural data gathered over the last decades can be used to model GPCR targets for which no experimental structures are available, and the use of structure-based virtual screening (SBVS) campaigns to identify ligands with tailored pharmacological properties. In paper I, we investigated how template selection affects the virtual screening performance of homology models of the D2 dopamine receptor (D2R) and serotonin 5-HT2A receptor (5-HT2AR). In papers II and III, SBVS methods were used to identify dual inhibitors of the A2A adenosine receptor (A2AAR) and an enzyme, which could be relevant for treatment of Parkinson’s Disease, and functionally selective D2R ligands from a focused library. Finally, we also investigated how structural information can complement computational and biophysical methods to model and characterize the A2AAR-D2R heterodimer (paper IV)