Roles for Membrane Receptors in Cellular Responses to External Cues; The Case of ErbB4 and Morphology Dynamics
EMSL Project ID
24827
Abstract
This proposal is a continuation of research pursued under EMSL User Proposal #22092. Understanding the mechanisms that underlie the cellular responses to the environment has been the subject of intensive research. Membrane proteins are found within the interface between the living cell and its surrounding environment and play crucial roles in the normal development, function and survival of the cell. Among membrane proteins, membrane receptors are of particular importance because of their role in transferring information across the cell-environment or cell-cell interface. Membrane receptors are activated upon the binding of small ligand molecules to specific sites in their extracellular domain, and in turn, they initiate molecular cascades in the intracellular environment, ultimately dictating the cellular response to the extracellular cue. Cells change their morphology in response to environmental cues. For example, cells extend cellular structures or migrate as the result of asymmetric changes in their morphology in response to external signals. The involvement of membrane receptors, specifically receptor tyrosine kinases, in morphological changes that underlie cell migration or extension has been observed, but the underlying mechanism is unclear. Changes in cell morphology must be involved with dynamic changes in the actin filaments. The dynamics of the actin monomers and filaments is a highly regulated process involving arrays of proteins and activation cascades, which in many cases are initiated in response to the activation of membrane receptors. Here we propose to focus on a receptor tyrosine kinase, ErbB4, which is a membrane receptor that has been implicated in processes that require changes in cell morphology. The mechanisms of its function, however, are far from being understood. ErbB4 and its ligand, neuregulin-1 (NRG-1), have been shown to play a role in cell migration and in the outgrowth of neuronal processes, which are fine structures that harbor the synaptic sites where information is transferred across the interface between cells. Recent observations also suggest that ErbB4 and NRG1 play a role in the formation of the synapse itself, which is a highly complex and challenging submicron membrane structure. The investigation of these sub-micron structures and their resident proteins in their natural living cell requires tools that enable insights into the intact cell with high spatial and temporal resolutions. We will take advantage of non-conventional imaging techniques that have been established in EMSL, which allow the investigation of nanoscale cellular structures, and individual membrane receptors and their interactions, in real time and in the live cell. Furthermore, EMSL's capabilities in high resolution quantitative fluorescence recovery after photobleaching (FRAP) and fluorescence resonance energy transfer (FRET) imaging and spectroscopy will be used to identify the dynamic changes in cellular structures and in receptor interactions in response to receptor activation within these submicron structures in the live cell. Using the above capabilities, we will investigate the possibility that ErbB4 induces the outgrowth of developing neurites and filopodia by increasing the dynamic state of the actin system upon its activation by the external cue or ligand. The new information will gain new insights into the mechanisms and interactions at the cell environment interface, which dictate the cellular responses to the environmental cues.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2007-06-15
End Date
2010-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
6 Orr G, Panther DJ, Cassens KJ, Phillips JL, Tarasevich BJ, Pounds JG. Syndecan-1 mediates the coupling of positively charged submicrometer amorphous silica particles with actin filaments across the alveolar epithelial cell membrane. Toxicology and Applied Pharmacology. 2009, 236, 210-220.
6 Orr G, Panther DJ, Cassens KJ, Phillips JL, Tarasevich BJ, Pounds JG. Syndecan-1 mediates the coupling of positively charged submicrometer amorphous silica particles with actin filaments across the alveolar epithelial cell membrane. Toxicology and Applied Pharmacology. 2009, 236, 210?220.
Dong J, Opresko LK, Chrisler W, Orr G, Quesenberry RD, Lauffenburger DA, Wiley HS. (2005) The Membrane-anchoring Domain of Epidermal Growth Factor (EGF) Receptor Ligands Dictates Their Ability to Operate in Juxtacrine Mode. Molecular Biology of the Cell. Jun;16(6):2984-98.
Hendriks BS, Orr G, Wells A, Wiley HS, Lauffenburger DA. (2005) Parsing ERK activation reveals quantitatively equivalent contributions from EGFR and HER2 in human mammary epithelial cells. Journal of Biological Chemistry, 280(7):6157-69.
Orr G, Hu D, Özçelik S, Opresko LK, Wiley HS, Colson SD. (2005) Cholesterol Dictates the Freedom of EGF Receptors and HER2 in the plane of the membrane. Biophysical Journal. 89(2):1362-73. Epub 2005 May 20.