Biomechanics of Tissue Motility

ABSTRACT During nervous system development, cells and tissues often move to assemble into layers and clusters. To do this, the cells need to generate force and transmit force to their surroundings to push themselves forward. In vitro studies have identified a three- step mechanism for how cells move on a substrate: cells protrude in the direction of migration, adhere to the substrate and detach in the back. Whether cells in vivo use the same mechanism to move is unclear because experimental limitations have hindered similar studies. This project will address this challenge and combine a novel protein depletion approach that offers spatial and temporal control with high resolution imaging to ask how a tissue pushes itself forward in a living animal. For these studies, we will use the zebrafish posterior lateral line primordium migration as a vertebrate model system because of its amenability to powerful genetic perturbations and imaging. To reveal the molecular basis of force generation and transmission in the migrating primordium, we will determine how RhoA pulses are generated, how RhoA-induced cell contractions pull cells forward, whether focal adhesions transmit the force generated through cell contractions to the surroundings and how the surroundings respond to the friction force. Since RhoA signaling and focal adhesion components are conserved in humans, the proposed studies will provide necessary context to better model and understand developmental nervous system defects and inform strategies to correct these defects.