During the morphogenetic movements of gastrulation, cells that will form internal tissues move into the interior of the developing embryo. We use the nematode C. elegans as a simple model to understand some of the basic cellular processes that control gastrulation movements. C. elegans is ideally suited for the study of gastrulation, since individual cell movements can be followed in the optically clear embryo and the genes involved can be found in genetic screens. Gastrulation movements begin when the contractile cytoskeletal protein non-muscle myosin accumulates at the contact-free surfaces (those facing the exterior of the embryo) of specific cells, causing this surface to constrict and driving the cells into the interior of the embryo. We have identified a cell-contact-induced signaling pathway that regulates gastrulation movements by polarizing early embryonic cells. In worm embryos, contact-induced polarity is required for gastrulating cells to properly position myosin at their apical surfaces. A mechanistically similar polarization occurs in mammals, and is thought to help drive the first lineage divergence – separation of inner and outer cells into embryonic and extra-embryonic populations, respectively.
Projects in the lab include understanding how cell contacts induce polarity and translate polarity information into cytoskeletal asymmetries that drive directional cell movement; investigating the triggers that induce gastrulation movements in specific cells; and learning how cells that are internalized during gastrulation polarize again during organogenesis, as they become epithelial cells and assemble cell-cell junctions.