The actin cortex is a thin meshwork of actin filaments, myosin motors and actin-binding proteins that lies below the membrane. Gradient of tension in the actin cortex play an essential role in driving the morphogenesis of cells and tissues. I will present work examining the role of the cortex in controlling cell surface tension and the shape of monolayers.

Surface tension in single cells is controlled by the activity of myosins in the submembranous actin cortex, which is controlled by RhoGTPases - key regulators of the cytoskeleton and contractility. In turn, RhoGTPase activity is regulated by RhoGEFs that activate them and RhoGAPs that inactivate them. Despite their central role in cell morphogenesis, we know little about how RhoGEFs control cell surface tension. I will present work examining the link between signalling and cell mechanics using AFM, imaging, and optogenetics.

During embryonic morphogenesis, tissue shape arises from interactions between cells. In tissues, the spatial patterning of cellular surface stresses generated by myosins interplays with intercellular adhesions to yield complex shapes. I will present new work that uses optogenetics to investigate the link between the location of signalling and myosin activity at the cellular-scale and shape at the tissue-scale.