EAGER: Dynamic Affinity for Regulation of Cell Signaling

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PI: Cheng DongProposal ID: 1330663Overview:The ability to understand cell-microenvironment communication is important in not only basic life science research, but also various biomedical applications such as cancer research and regenerative medicine. Because cell receptors are the major players for a cell to sense its microenvironment, the understanding of cell-microenvironment communication needs deep insights into molecular interactions between cell receptors and their ligands that can be cell receptors of another cell, free biomolecules, or extracellular matrix components. However, current understandings of these biomolecular interactions come primarily from the examination of the properties of cell receptors at a fixed or optimal functional state despite the dynamic nature of cell receptors and their ligands. Few if any studies have been carried out to understand how dynamic affinities drive intercellular communication that eventually regulates intracellular signaling pathways. Therefore, this proposal is aimed at exploring how dynamic affinity determines intracellular signaling by using both engineering and biological methods.Intellectual Merit:The objective of this proposal is to discover and understand a new mechanism for the regulation of cellular signaling transmission driven by dynamic affinities. To achieve this objective, CD82 and integrins will be used as a receptor model, and tumor cells and endothelial cells will serve as a cell model. Previous studies including those performed at PI's lab have suggeste that CD82 is associated with integrins that molecular interactions may influence cell phenotypes. However, it remains largely unknown on whether integrin binding affinities alter endothelial signaling due to a lack of experimental techniques to perform these analyses. Supported by these previous studies, it is hypothesized that increase of inducible CD82 expression decreases integrin-binding affinities, which inhibits tumor induced gap formation and tumor cell extravasation. Two high-risk tasks are proposed to validate this untested hypothesis. The first task aims to develop a new and innovative quasi-3D microscopy imaging technique to interrogate how integrin conformational states or binding affinities change with the level of CD82 expression. The second task is to understand how the dynamic change of integrin binding affinities determines intracellular signaling pathways and actin dynamics. It is expected that the study of this model system would lead to deep insights into the interactions between tumor cells and endothelial cells. Specifically, it will provide valuable insights into the mechanisms by which integrin-binding affinity affects endothelial cell strains in the actin cytoskeleton, protein kinase activity, and changes in VE-cadherin disassembly near the endothelial cell junctions over time.Broader Impacts:Education and outreach: The PI plans to build a new interdisciplinary research and education program, which aims to improve the participation of students at different levels, particularly underrepresented minorities and persons with disabilities in science and engineering. Students will be recruited through existing outreach programs from predominantly teaching institutions in Pennsylvania. Students will form research teams to develop computer programs, conduct laboratory work, analyze experimental results, write research papers, present findings in conferences, and maintain a web-based dissemination of results. Interdisciplinary and Transformative Traits: This high risk and high payoff project reflects a new paradigm, as prior studies were only focused on how binding affinities regulate cell adhesion rather than intramolecular cell signaling, which is the focus of this EAGER project. A new interdisciplinary research direction will be opened at the interface of engineering, biology, physiology, and biophysics. Importantly, the success of this proposal holds great potential to transform the ways that cell-cell communication is studied, and current / future bioengineering is developed for biomedical applications. Thus, the proposed research may not be viewed as "regular" questions or approaches, and has an appropriateness of the EAGER mechanism.