Seven transmembrane-spanning receptors (7TMRs or G protein-coupled receptors, GPCRs) represent the largest family of signal-transducing molecules known. For example, 7TMRs comprise more than 4% of the genes in Caenorhabditis elegans. 7TMRs convey signals for light and many extracellular regulatory molecules, such as, hormones, growth factors and neurotransmitters, that regulate every cell in the body. Dysregulation of 7TMRs has been found in a growing number of human diseases and 7TMRs have been estimated to be the targets of more than 30% of the drugs used in clinical medicine today. Thus, discovery of probes/drugs for 7TMRs is an important goal of biomedical research. We have begun our research using high throughput screening (HTS) for low molecular weight (LMW) ligands for 7TMRs with the receptor for thyroid-stimulating hormone (TSH-R) and plan to extend these studies for HTS of the receptor for free fatty acids (GPR40/FFAR1). During this year, we developed a cell-based assay for activation of TSH-R by LMW agonists and a complementary assay for LMW inhibitors of TSH stimulation of TSH-R. We then modified it to work in a 1536-well format so that it could be used in a HTS format and screen a 79,000 compound library. Our preliminary analysis of the HTS results show that we have identified at least two new agonists for TSH-R that show excellent selectivity because they do not activate the closely related receptors for luteinizing hormone or follicle-stimulating hormone.
