Spatiotemporal Dynamics of Cellular Protein Networks on Membranes

Type of Award: Catalyst
Date Awarded: January 2008
Award End Date: April 2009
Amount Awarded: $ 200,000.00
PI(s): Wonhwa Cho, PhD, UIC; Eduardo Perozo, PhD, UChicago; Hui Lu, PhD, UIC;

Abstract: Cellular responses to external stimuli are mediated by diverse signal transduction pathways that involve multiple transmembrane receptors and a large number of cellular proteins. Because dysfunctional or unregulated cell signaling pathways are known to cause a wide range of human diseases, including cancer, diabetes, autoimmune diseases, and inflammatory diseases, cell signaling pathways offer many attractive drug targets, as witnesses by the remarkable success of a signaling kinase inhibitor, Gleevec, against chronic myelogenous leukemia. Regulation of cell signaling involves a myriad of molecular interactions, including protein-protein interactions. Determination of the protein-protein interaction network and understanding of their regulation during cell signaling are the key elements of functional proteomics and systems biology, and may lead to development of a new generation of specific inhibitors directed toward various signaling pathways. In general, cellular protein-protein interactions are tightly regulated both spatially and temporally and, consequently, the success of proteomics and systems biology studies critically depends on the spatiotemporal resolution of protein-protein interactions. Recent studies have indicated that the spatial regulation is the key to the successful orchestration of cellular protein interactions and information flow. Furthermore, cellular membranes serve as the main sites of protein complexes and networks and direct interaction of proteins with various membrane lipids is critical for spatial regulation of protein networking. The Cho and Lu laboratories recently developed and/or optimized a bioinformatics-based algorithm for predicting lipid-binding proteins, high-throughput in vitro and cellular methods for determining lipid binding and subcellular locations of proteins, cellular single molecule techniques, and a systems biology analysis protocol. On the basis of these methods as well as structural, spectroscopic, and computational methodologies developed in the Perozo laboratory, we propose to study the lipid binding properties of all major modular domains that mediate cellular protein-protein interactions and networking. In this proposal, we will focus on the PDZ domain that is the most abundant protein interaction module, plays a key role in the localization of a large number of signaling proteins, and is an important target for drug development. We will predict the lipid binding PDZ domains, determine their lipid specificities and membrane binding mechanisms, and finally elucidate how their lipid binding regulates the spatiotemporal dynamics of signaling complexes and signaling network. These studies will lead to better understanding of when and where signaling proteins interact with each other and thereby aid in development of a new type of specific and potent reagents that interfere with or boost particular protein-protein interactions.