Epithelial Cell Reintegration: The Ins and Outs

Epithelial tissues perform a range of specialized functions, including secretion, absorption, and protection. All of these functions require that the component cells remain tightly packed. This is a particular challenge during development, when new cells are being added to the tissue. Work in a number of systems shows that one answer to this challenge is cell reintegration: epithelial cells can be born protruding from the sheet, then reincorporate into it. Our lab aims to understand this process. Our previous work demonstrated that reintegration in the Drosophila follicular epithelium relies on Fas2 and Neuroglian, homophilic adhesion molecules that promote axonal growth and pathfinding. Our model is that these and other neuronal adhesion factors coordinate with the juxtamembrane spectrin-based cytoskeleton to form an evolutionarily-conserved assembly that maintains epithelial integrity during proliferation. We are currently testing this possibility in other epithelial systems, including mammalian epithelial organoids.