Probing Mechanisms of Cell Motility in Electric Fields

Columbia University, New York NY

Investigators

Abstract

This project will probe mechanisms by which cells move in electric fields. Epithelial cells are known to generate electric fields, and cells such as fibroblasts, have been shown to respond to electric fields by moving towards the cathode. This project investigates how electric fields cause cells to migrate in a specific direction. Experiments will use the fibroblast as a model system to test the membrane electrophoresis hypothesis that cell proteins move within their surface membrane to polarize on one side, inducing cells to move towards the cathode. To test this hypothesis, fibroblasts will be manipulated with enzymes and very mild chemical reactions to change the charge of proteins on their surface. If the hypothesis is correct, altering the charge of surface proteins will alter the speed, directionality, and appearance of migrating cells. To test further whether redistribution of surface charge is necessary and/or sufficient to induce cell migration in an electric field, candidate molecules that might be expected to polarize towards the cathode and enhance motility will be assayed, and the quantity of plus or minus surface charge, known as zeta potential, will be measured. Electric field-migration will be used as a system to find features common to all types of cell migration. The investigators will focus on the role of microtubules and focal adhesions. These experiments will utilize microscopic imaging of living, migrating cells that contain fluorescent microtubules or adhesion components. Various perturbations to the stability or chemical composition of the microtubules and adhesions will be used to test the focal adhesion turnover hypothesis, which posits that unstable (dynamic) microtubules contact focal adhesions, become stabilized there, and then act as specialized transport tracks for factors that make the adhesions less stable, as needed for the next step in cell crawling. Building upon the multidisciplinary expertise of a cell biologist and a biomedical engineer, this project will further the goals of improving biological understanding of cell migration, a fundamental cellular process. This project will provide research training for post-doctoral associates, graduate students, and undergraduates.