Supracellular actomyosin assemblies during development.

Changes in cell shape are one of the driving forces of tissue morphogenesis. Contractile cytoskeletal assemblies based on actomyosin networks have emerged as a main player that can drive these changes. Different types of actomyosin networks have been identified, with distinct subcellular localizations, including apical junctional and apicomedial actomyosin. A further specialization of junctional actomyosin are so-called actomyosin 'cables', supracellular arrangements that appear to stretch over many cell diameters. Such actomyosin cables have been shown to serve several important functions, in processes such as wound healing, epithelial morphogenesis and maintenance of compartment identities during development. In the Drosophila embryo, we have recently identified a function for a circumferential actomyosin cable in assisting tube formation. Here, I will briefly summarize general principles that have emerged from the analysis of such cables.