Project Summary
Highly ordered, directed movement in collective cell migration is a result of the magnitude of coordination
and communication that takes place at both the cellular and tissue level. In this proposal, we focus on
understanding the mechanisms that contribute to the system behaving as a ‘collective’ to achieve such
phenomenon. The cardiopharyngeal progenitors of the tunicate Ciona provide the simplest model of collective
cell migration, with cohesive bilateral cell pairs polarizing and migrating between the ventral epidermis and trunk
endoderm. Bernadskaya & Yue et al. 2021 found that the collective cell migration of Ciona exhibits supracellular
characteristics; while each cell has the machinery to migrate individually, for successful development, the cells
travel together and take on the identity of either the ‘leader’ or ‘trailer’. How this collective polarity is established
and communicated between the two cells, and the type of information being exchanged, remains to be
elucidated. We propose that this collective migration is driven by a “rear-engine” with supracellular polarity, as
mechanical information flows from the trailer cell to the leader cell. We speculate that the cell:cell junction serves
as a point of plasticity; preliminary work has shown that the junction has relatively low levels of actomyosin,
allowing it to be under low tension and easily deformable. We hypothesize the two cells are utilizing cell shape
– specifically the direction and degree of deformation at the cell:cell junction – and hydrostatic pressure as a
method for mechanical coupling. To test our hypothesis, we will use in vivo images to reverse-engineer forces,
extract force measurements, and build computational models of migration. Then, we will experimentally validate
the role of the cell:cell junction as an information hub contributing to supracellular polarity, cytoskeletal
organization, as well as force generation and transmission.