Cancer metastasis occurs when cells migrate from the primary tumor and invade other tissues. The long-term goal of this study is to characterize the Na+/H+ exchanger regulatory factor 1 (NHERF1) scaffold in cell migration in order to aid in design of drugs that could inhibit this process to prevent metastasis. We propose to investigate the role of the scaffold protein NHERF1 at the leading edge of migrating cells in the coordination of protein kinase D (PKD) and PH domain Leucine-rich repeat Protein Phosphatase (PHLPP) signaling;NHERF1 has been shown to be involved in cell movement and, in independent studies, PKD has been shown to modulate the actin cytoskeleton necessary in this process. We will characterize the NHERF1 scaffold and its role in the coordination of actin remodeling at the leading edge of migrating cells through use of fluorescence imaging, novel miniSOG (singlet oxygen generator) technology that is revolutionizing electron microscopy, as well as fluorescence resonance energy transfer (FRET) techniques. Through FRET, we can image the dynamic changes in protein conformation within NHERF1 as well as changes in protein-protein interactions between NHERF1 and its actin-binding partner ezrin;such changes reflect alterations in NHERF1 conformation between its inactive and active state. We will then investigate the impact that two mutations identified in human cancers within NHERF1 have on its function. These studies could provide a basis for the design of novel therapeutics to prevent cancer metastasis.
This project aims to elucidate the role of the scaffold protein NHERF1 plays in coordinating signals that regulate cell movement. These studies will give us more insight into the molecular mechanisms of NHERF1 function in cell migration, as well as into the roles of the signaling proteins, PKD and PHLPP, at the NHERF1 scaffold. Such knowledge will aid in the design of methods to modulate the NHERF complex such that we can limit cell migration, a process that, in cancer, results in metastasis.