Transporter Elucidation Center at the University of California, San Francisco

PROJECT SUMMARY Membrane transporters in the Solute Carrier (SLC) and ATP Binding Cassette (ABC) superfamilies play essential roles in the transmembrane movement of solutes including drugs, dietary supplements and nutrients. Transporters on the polarized membranes of epithelial cells such as those in the placenta, mammary gland and gut or polarized endothelial cells such as those of the Blood Brain Barrier (BBB) play essential roles in transcellular flux of their substrates. A significant gap in our understanding of both SLC and ABC transporters exists as many transporters have not been systematically characterized and the range of substrates is not known or poorly understood. In response to RFA-HD-23-003, we propose to establish a multi-disciplinary Transporter Elucidation Center at the University of California San Francisco (TECUCSF), which brings together expert scientists in transporter biology and pharmacology, membrane transporter structural biology, computational biology, and chemo-informatics. The overall goal of the TECUCSF is to elucidate the ligand specificity, protein structure and cellular localization of SLC and ABC transporters in the human BBB. Based on preliminary studies from our global proteomic analyses, we will prioritize a list of 30 highly expressed and understudied/orphan SLC and ABC transporters in the human BBB (BBB-30). Key knowledge gaps of these 30 transporters will be addressed by research conducted under three aims. For Aim 1, we will perform in silico docking of neuroactive drugs, nutrients, and dietary supplements using experimentally determined structures or structures based on computed structural models of transporters in the BBB-30. For each of these transporters, we will create recombinant cell lines expressing the transporter and functional assays to validate the in silico results, which will result in the discovery of ligands for both understudied and orphan transporters. For Aim 2, we will use cryoEM to determine the structure of selected transporters in the BBB-30, which do not have available structures. Finally, for Aim 3, we will perform localization of the BBB-30 in human endothelial cell models using available antibodies and flux studies will be performed to confirm the localization. To support our studies and enhance studies in the Transporter Elucidation Network (TEN), three cores will be established: TECUCSF Informatics and Modeling Core; TECUCSF Structure Core; and TECUCSF Function Core. The cores will provide support for research proposed in each of the three aims, as well for investigators in the TEN. TECUCSF will work together with other TECs within the TEN to generate knowledge and resources that will be shared with the broader research community through RESOLUTE to advance our understanding of nutrient, drug, and dietary supplement constituent transport across the BBB.