Interkinetic nuclear migration and basal tethering facilitates post-mitotic daughter separation in intestinal organoids

Abstract

Homeostasis of renewing tissues requires balanced proliferation, differentiation and movement. This is particullary important in the intestinal epithelium where lineage tracing suggests that stochastic differentiation choices are intricately coupled to position relative to a niche. To determine how position is achieved we followed proliferating cells in intestinal organoids and discovered that behaviour of mitotic sisters predicted long-term positioning. We found that normally, 70% of sisters remain neighbours while 30% lose contact and separate after cytokinesis. These post-mitotic placements predict longer term differences in positions assumed by sisters: adjacent sisters reach similar positions over time; in a pair of separating sisters, one remains close to its birthplace while the other is displaced upward. Computationally modelling crypt dynamics confirmed that post-mitotic separation leads to sisters reaching different compartments. We show that interkinetic nuclear migration, cell size, and asymmetric tethering by a basal process contribute to separations. These processes are altered in Adenomatous polyposis coli (Apc) mutant epithelia where separation is lost. We conclude that post-mitotic placement contributes to stochastic niche exit and when defective, supports the clonal expansion of Apc mutant cells.