Biophysics Seminar Series - Karen Kasza (Sloan Kettering) "Spatiotemporal control of the forces that shape tissues"

Apr 7, 2014, 12:00 pm1:00 pm
Joseph Henry Room


Event Description
During embryonic development, the forces generated by myosin II must be controlled in space and time to shape simple epithelia into tissues and organs with complex form and structure. Molecular-level properties of myosin regulation and force generation have been extensively studied in vitro, but it is not understood how these molecular properties are translated to cell and tissue length scales to achieve the complex patterns of forces that shape tissues. In one dramatic example in the Drosophila melanogaster embryo, polarized patterns of myosin activity are required for oriented cell rearrangements that drive rapid doubling in tissue length along the head-to-tail axis. Our approach has been to use systematic and quantitative experimental studies to gain insight into how macroscopic tissue elongation arises from force generation at the molecular level. We have generated embryos expressing myosin variants engineered to alter specific aspects of regulation and motor function¬. For example, myosin II regulatory light chain phosphorylation promotes the assembly of myosin into active contractile filaments and controls the level of myosin activity. Surprisingly, we find that myosin variants that mimic phosphorylation accelerate cell rearrangements but alter the spatial pattern of myosin localization and force generation in the tissue, resulting in reduced tissue elongation. Our results suggest a trade-off between the speed and orientational precision of cell rearrangement and provide insight into general principles of efficient tissue remodeling.
Lunch @ 11:45 in Joseph Henry talk at noon.