Abstract
The enteric neurotransmitter acetylcholine governs important intestinal epithelial secretory and immune functions through its actions on epithelial muscarinic Gq-coupled receptors such as M3R. Its role in the regulation of intestinal stem cell function and differentiation, however, has not been clarified. Here, we find that nonselective muscarinic receptor antagonism in mice as well as epithelial-specific ablation of M3R induces a selective expansion of DCLK1-positive tuft cells, suggesting a model of feedback inhibition. Cholinergic blockade reduces Lgr5-positive intestinal stem cell tracing and cell number. In contrast, Prox1-positive endocrine cells appear as primary sensors of cholinergic blockade inducing the expansion of tuft cells, which adopt an enteroendocrine phenotype and contribute to increased mucosal levels of acetylcholine. This compensatory mechanism is lost with acute irradiation injury, resulting in a paucity of tuft cells and acetylcholine production. Thus, enteroendocrine tuft cells appear essential to maintain epithelial homeostasis following modifications of the cholinergic intestinal niche.
Highlights
The enteric neurotransmitter acetylcholine governs important intestinal epithelial secretory and immune functions through its actions on epithelial muscarinic Gq-coupled receptors such as M3R
These enteroendocrine tuft cells upregulate important signaling pathways to sustain epithelial homeostasis, which is in part orchestrated by an increase of mucosal Ach release, suggestive of a compensatory response circuit to maintain epithelial cholinergic input
In line with the importance of M3R for intestinal homeostasis[24], we found that the expression of Chrm[3] in intestinal epithelial-enriched WT samples was the highest among cholinergic receptors, followed by Chrm[1] (Fig. 1c)
Summary
The enteric neurotransmitter acetylcholine governs important intestinal epithelial secretory and immune functions through its actions on epithelial muscarinic Gq-coupled receptors such as M3R. Prox1-positive endocrine cells appear as primary sensors of cholinergic blockade inducing the expansion of tuft cells, which adopt an enteroendocrine phenotype and contribute to increased mucosal levels of acetylcholine. This compensatory mechanism is lost with acute irradiation injury, resulting in a paucity of tuft cells and acetylcholine production. Prox1-positive cells appear as the primary sensors of cholinergic interruption, as they orchestrate the expansion and differentiation of progenitors into an enteroendocrine tuft cell phenotype These enteroendocrine tuft cells upregulate important signaling pathways to sustain epithelial homeostasis, which is in part orchestrated by an increase of mucosal Ach release, suggestive of a compensatory response circuit to maintain epithelial cholinergic input
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