The Molecular Basis of Cadherin-Mediated Cell Adhesion

In this project the PI will study the molecular mechanisms that underlie cell-cell adhesion. The project is multi-scale and interdisciplinary in nature and the strategy that is being developed can serve as a model for other such efforts that integrate computational and experimental methods in cutting edge areas of modern biology. A particularly important element of this research is the training of scientists with expertise in both computational and experimental work including joint mentoring from senior researchers with very different backgrounds. The training of women and minority scientists is an integral component of this research program. A number of women postdocs working on previous NSF funded projects have gone on to successful independent research careers and this tradition will be maintained. In addition, each summer the lab hosts minority undergraduate students and accepts high school students as interns. Both undergraduate and graduate minority students trained in the lab have become highly successful research scientists. The outcomes of this project will have substantial impacts on the workforce development and on the development of predictive tools in nanobiotechnology industry.

The objective of this research project is to elucidate the molecular mechanisms that underlie cadherin-mediated cell-cell adhesion. Cadherins are cell surface molecules that also have a trans-membrane region and a cytoplasmic domain that interacts with the actin cytoskeleton. Classical cadherins consist of five extracellular cadherin (EC) domains connected by linker regions. Upon initial encounter of two cells, cadherins on opposing membrane surfaces bind to one another and initiate a series of events, beginning with the formation of large ordered assemblies, that ultimately lead to cell-cell adhesion. The project involves integrated experimental and computational studies on the structure, dynamical properties and function of classical cadherins. Analysis of existing three-dimensional structures, the design of site directed mutants, binding affinity measurements and Electron Paramagnetic Resonance (EPR) spectroscopy will be used to elucidate the factors that enable cadherins to bind to one another in a highly specific fashion, despite being similar to one another in sequence and structure. EPR will also be used to study changes in cadherin flexibility resulting from cell-cell contact and the formation of trans (different cell) adhesive bonds. Coarse-grained molecular simulations will be used to understand how these changes in flexibility lead to the formation of cis (same cell) interactions that drive the lateral clustering of cadherins on cell surfaces. The project will lead to a deeper understanding of this important class of molecules and will also reveal general principles regarding the mechanisms employed by other families of adhesion molecules to mediate cell-cell recognition. This project is jointly supported by Molecular Biophysics in the Division of Molecular and Cellular Biosciences in the Directorate for Biological Sciences and the Computational Physics Program in the Division of Physics in the Mathematical and Physical Sciences Directorate.