FRET-based tension measurement across actin-associated mechanotransductive structures using Lima1

During embryogenesis, mechanical forces play important roles in morphogenesis and tissue differentiation. To measure these forces, we developed a new Förster resonance energy transfer (FRET)-based tension sensor that uses the actin-associated protein, Lima1. The sensor was validated in HeLa cells where we found the FRET index decreased or increased in response to changes in the cellular environment. Introducing the sensor into Xenopus embryos enabled us to observe tension distributions and sequential changes over the entire embryo. We found that during neural tube closure, neural ectodermal cells showed a gradual decrease in their FRET index, indicating they generate higher tension with the progression of neural tube closure. With appropriate controls and application, our Lima1 tension sensor has the ability to uncover and define other tension distributions and their functions in development and differentiation.