Cytokinesis genes regulate ring canal patterning and follicle cell differentiation in Drosophila.

UNLABELLED: Stable intercellular bridges that form through incomplete cytokinesis are present in a wide variety of cell types but their function in somatic cell differentiation is not well understood. Using super-resolution confocal microscopy, we identified a stepwise process of ring canal development in the follicle cells of the Drosophila ovary. Using a custom-trained deep learning model to aid in 3D image segmentation and follicle cell quantification, we found that ring canals are more heterogeneous at the early prefollicle stages compared to the more differentiated later stages. In addition, we found that depletion of the septin, peanut , caused cytokinetic defects but did not disrupt ring canal formation, whereas depletion of the ESCRT III gene, shrub , increased ring canal number in prefollicle cells and caused proliferation and differentiation phenotypes. Our findings identify cytokinesis and ring canal formation as a point of regulation in the patterning of proliferation and differentiation in the Drosophila follicle stem cell lineage. SUMMARY: Somatic ring canals in the Drosophila ovary develop through a stepwise series of states and are a point of regulation of proliferation and differentiation toward a postmitotic cell fate called stalk cells.