Local Control of Intestinal Stem Cell Homeostasis by Enteroendocrine Cells in the Adult Drosophila Midgut

SummaryBackgroundEnteroendocrine cells populate gastrointestinal tissues and are known to translate local cues into systemic responses through the release of hormones into the bloodstream.ResultsHere we report a novel function of enteroendocrine cells acting as local regulators of intestinal stem cell (ISC) proliferation through modulation of the mesenchymal stem cell niche in the Drosophila midgut. This paracrine signaling acts to constrain ISC proliferation within the epithelial compartment. Mechanistically, midgut enteroendocrine cells secrete the neuroendocrine hormone Bursicon, which acts—beyond its known roles in development—as a paracrine factor on the visceral muscle (VM). Bursicon binding to its receptor, DLGR2, the ortholog of mammalian leucine-rich repeat-containing G protein-coupled receptors (LGR4-6), represses the production of the VM-derived EGF-like growth factor Vein through activation of cAMP.ConclusionsWe therefore identify a novel paradigm in the regulation of ISC quiescence involving the conserved ligand/receptor Bursicon/DLGR2 and a previously unrecognized tissue-intrinsic role of enteroendocrine cells