Cell adhesion marker expression dynamics during fusion of the optic fissure

Tissue fusion is a criHcal process that is repeated in mulHple contexts during embryonic development and shares common aYributes to processes such as wound healing and metastasis. Ocular coloboma is a developmental eye disorder that presents as a physical gap in the ventral eye, and is a major cause of
childhood blindness. Coloboma results from fusion failure between opposing ventral reHnal epithelia, but there are major knowledge gaps in our understanding of this process at the molecular and cell behavioural levels. Here we catalogue the expression of cell adhesion proteins: N-cadherin, E-cadherin, R-cadherin, ZO-
1, and the EMT transcripHonal acHvator and cadherin regulator SNAI2, in the developing chicken embryonic eye. We find that fusion pioneer cells at the edges of the fusing opHc fissure have unique and dynamic expression profiles for N-cad, E-cad and ZO-1, and that these are temporally preceded by expression of
SNAI2. This highlights the unique properHes of these cells and indicates that regulaHon of cell adhesion factors may be a criHcal process in opHc fissure closure.