Optogenetic Inhibition of Rho1-Mediated Actomyosin Contractility Coupled with Measurement of Epithelial Tension in Drosophila Embryos

Our research studies tissue morphogenesis, the formation of complex three-dimensional tissue structures in development. We are interested in the genes and the molecules that regulate morphogenesis and seek to understand the physical principles underlying morphogenesis. For example, how mechanical forces are generated and how they drive tissue rehabilitation.

Contractile forces generated by filamentous actin and non-muscle myosin II, also known as actomyosin contractility, is one of the most important forces that drive tissue morphogenesis. Our current research addresses how actomyosin contractility mediates the folding of blood epithelial cell sheets, a fundamental tissue construction mechanism in development. An in-depth understanding of the role of actomyosin contractility in epithelial folding and other morphogenetic processes requires approaches that can quickly inactivate actomyosin at designated time and location, and records the immediate impact of tissue behavior and properties.

However, this is difficult to achieve using conventional genetic approaches. The approach described in this protocol is designed to address how cells and tissues respond to sudden changes in mechanical forces that normally drive tissue remodeling. This is an important question but has been difficult to tackle due to limited approaches that can quickly alter mechanical forces in intact tissues.

In this study, we developed an optogenetic tool to inactivate actomyosin at specific tissue regions in Drosophila embryos quickly. We found that combining these two with laser ablation to investigate the direct impact of actomyosin contractility on tissue mechanics in epithelial folding. Our findings provide new insights into the mechanical mechanism apical constriction media to epithelial folding.

With manual modifications, the protocol can be easily adapted to study the function of actomyosin contractility in a wide range of morphogenetic processes.