RT Journal Article SR Electronic T1 Ecdysone regulates the Drosophila imaginal disc epithelial barrier, determining the duration of regeneration checkpoint delay JF bioRxiv FD Cold Spring Harbor Laboratory SP 2020.07.16.207704 DO 10.1101/2020.07.16.207704 A1 DaCrema, Danielle A1 Bhandari, Rajan A1 Karanja, Faith A1 Yano, Ryunosuke A1 Halme, Adrian YR 2020 UL http://biorxiv.org/content/early/2020/07/18/2020.07.16.207704.abstract AB Regeneration of Drosophila imaginal discs, larval precursors to adult tissues, produces a systemic response, a regeneration checkpoint that coordinates regenerative growth with developmental progression. This regeneration checkpoint is coordinated by the release of the relaxin-family peptide Dilp8 from regenerating tissues. Secreted Dilp8 protein can be detected within the imaginal disc lumen. The disc epithelium separates from the lumen from the larval hemolymph and the targets for Dilp8 activity in the brain and prothoracic gland. Here we demonstrate that the imaginal disc epithelial barrier limits Dilp8 signaling and checkpoint delay. We also observe that the wing imaginal disc barrier becomes more restrictive during development, becoming impermeable only at end of the final larval instar. This change in barrier permeability is driven by the steroid hormone ecdysone and correlates with changes in localization of Coracle, a component of the septate junctions that is required for the late, impermeable epithelial barrier. Based on these observations, we propose that the imaginal disc epithelial barrier regulates the duration of the regenerative checkpoint, providing a mechanism by which tissue function can signal the completion of regeneration.Summary Statement Ecdysone signaling directs the Drosophila third instar imaginal disc epithelial barrier to mature, becoming more restrictive. This mature barrier limits Dilp8 signaling and determines the duration of the regeneration checkpoint.Competing Interest StatementThe authors have declared no competing interest.