Living cells and tissues have the ability to generate directed forces and to remodel themselves. Both abilities are at the core of what defines life. How can a cell maintain its mechanical integrity while being dynamic, flexible and remodeling itself in space and time? We now know a lot about the mechanics of individual molecules. Our understanding of how molecules work together to create force in a cell is much weaker. Biological systems are dynamic, sculpting themselves into new shapes by internal forces to accommodate their roles in a human or animal body; description of such structures defies current traditional mechanical frameworks. This Faculty Early Career Development (CAREER) project focuses on the mechanics of the kinetochore--the macromolecular machine that segregates chromosomes at cell division. Errors in its function can lead to disease (such as cancer) and birth defects. The project will develop new methods to measure the 'slip-clutch' forces that permit the molecules to slide and to generate forces at the correct times in order to properly separate the new daughter cells during cell division.
The aim of this CAREER award is to develop and use state-of-the-art tools to control mechanical force inside cells and probe how force regulates the slip-clutch of biological interfaces with the cytoskeleton - the cell's roadways and pillars. We focus on the slip-clutch interface that moves chromosomes at cell division, that of the kinetochore linking chromosomes to dynamic spindle microtubule tips. The kinetochore-microtubule interface resides deep inside cells, and thus tugging on it to probe its mechanics is particularly challenging. To probe its slip-clutch, we will use a novel and unique combination of tools: we will use laser ablation to control forces and probe material properties and grip strength (clutch), protein photomarking to probe dynamics (slip), and molecular tools to probe mechanisms regulating the interface's slip and clutch behaviors. Together, these will enable us to test the hypothesis that independent force-based mechanisms regulate the slip and the clutch.
