Homeostasis in adult tissues is maintained by resident stem cells and their progeny. Little is known about the regulation of tissue homeostasis by organ-organ interaction. Here we demonstrate that trachea-derived Decapentaplegic (Dpp), the main bone morphogenetic protein ligand in Drosophila, is essential for adult midgut homeostasis. We show that Dpp signaling is primarily activated in enterocytes (ECs). Depletion of Dpp signaling in ECs results in excess amounts of intestinal stem-cell-like cells and their progeny. Importantly, we find that Dpp is expressed specifically in tracheal cells that reach the intestinal cells through the visceral muscles. Depletion of dpp expression in tracheal cells phenocopies the Dpp loss-of-function defects in ECs. Our data demonstrate that the Drosophila trachea not only exchanges air for bodily needs but also produces a Dpp morphogen essential for neighboring tissue homeostasis. This work will provide important insights into the mechanisms of tissue homeostasis control by interorgan communication.
