Chemical Toolkit for Monitoring and Modulating Receptor Tyrosine Phosphatase Activity

With the support of the Chemistry of Life Processes program in the Division of Chemistry, Professor Amy Barrios from the University of Utah and Professor Brian Popp from West Virginia University are investigating phosphatase enzymes involved in cellular signaling. Protein phosphorylation and dephosphorylation controls many of the pathways of cellular communication. While the enzymes that add a phosphate group to protein targets (the kinases) are relatively well understood, much less is known about the enzymes that remove this phosphate signal (protein phosphatases). This project aims to develop a set of chemical tools that can be used to answer questions about the cellular locations of specific phosphatases, the impacts that signaling molecules outside the cell have on the activity of individual phosphatases inside the cell, and the roles that key phosphatases play in important signaling pathways. For example, this work centers on study of a family of phosphatase enzymes that are involved in neurological development. Chemical tools will be developed to monitor the activity of these phosphatases in cells, identify signaling molecules that activate them, and validate inhibitors that will block the activity of the phosphatases. The tools developed in this project will provide new biological insights that cannot be obtained readily in any other way. The project is also integrated into a larger effort to build a strong culture of excellence in mentoring for scientific research trainees by incorporating regularly cross-campus mentor training workshops. The long-term objectives of this work are to provide chemical approaches to studying receptor tyrosine phosphatase activity that can be used to answer key questions about the roles of these critical enzymes in cellular signaling pathways. The investigators have a strong track record of tailoring fluorogenic substrates and targeted inhibitors to individual tyrosine phosphatases and utilizing these tools both in vitro and in cells. This project is focused on the Leukocyte common Antigen-Related (LAR) subfamily of receptor tyrosine phosphatases. Fluorogenic peptide substrates with selectivity for the LAR phosphatases will be developed based upon the sequences of known biological substrates and validated for cellular applications. Potent and selective inhibitors for the LAR subfamily will be optimized and utilized to probe the roles of these enzymes in cellular signaling. Signaling molecules that act by binding to the extracellular portion of these receptor phosphatases to modulate intracellular phosphatase activity will be identified and investigated. The targeted chemical probes optimized and validated through this project will provide novel insights into the biological roles of LAR phosphatases. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.