Using genetics and optogenetics to dissect how Rho signaling is coordinated at distinct subcellular domains to drive epithelial tissue morphogenesis

Project Summary/Abstract During embryonic development, cellular cytoskeletal machinery produces mechanical forces to deform epithelial tissue sheets into complex structures. Although the gene and protein regulatory networks that direct development have been the focus of many studies, much less is known about how these patterned molecular programs generate cell and tissue-scale forces to physically sculpt developing tissues and organs. Convergent extension is a widely conserved morphogenetic process employed extensively across animal development, and its failure is associated with common congenital anomalies in humans. However, the nature of the subcellular forces directing tissue convergent extension remain poorly understood. Here, I propose using the Drosophila melanogaster embryo as a model for dissecting the interplay of the actomyosin-generated subcellular forces that direct cell intercalations during convergent extension. In Aim 1, I seek to quantify and correlate actomyosin dynamics at cell apices, junctions, and lateral domains during both germband extension, in which contractility at these domains cooperatively drives cell rearrangements, and ventral furrow formation, in which contractility at these domains drives both in-plane cell rearrangements and out-of-plane tissue bending. Then, using genetic mutants that disrupt actomyosin patterning in the early embryo, I plan to study how defects in coordination between apical, junctional, and lateral actomyosin contribute to perturbed developmental phenotypes. In Aim 2, I propose using optogenetic control of Rho signaling to specifically and simultaneously manipulate actomyosin at cell junctions, apices, and lateral domains in order to build a bottom-up understanding of how actomyosin coordination across different subcellular domains enacts distinct cell and tissue-scale morphogenetic processes. I will use insight gained from endogenous germband extension and ventral furrow formation processes to manipulate the frequency, duration, magnitude, and coordination of these distinct subcellular contractile optogenetic inputs, and measure the resulting cell and tissue deformations. These studies will elucidate the biochemical and mechanical nature of epithelial remodeling during convergent extension, contributing to our understanding of healthy and perturbed developmental processes.