Cells generate force to sculpt the myriad of tissue shapes that occur in an organism. Actomyosin contraction is an engine associated with cell and tissue shape changes. In epithelial cells, contraction of the apical actomyosin cortex can drive apical constriction. How apical actomyosin meshworks contract was not well understood. We have shown that in the non-muscle cells of the Drosophila embryo, the apical cortex adopts a polarized structure that topologically resembles a muscle sarcomere. We determined that establishing this sarcomere-like organization requires a dynamic upstream signaling network that surprisingly involves, not only activation, but inhibition of the RhoA GTPase, which activates actomyosin.
Dr. Martin is a Associate Professor at Massachusetts Institute of Technology.