A selective and augmentable butyrate-FFAR2 signal circuitry programs the cellular identity of enteroendocrine L-cells
Activation of free fatty acid receptor 2 (FFAR2) on enteroendocrine L-cells mediates secretion of glucagon-like peptide 1 (GLP-1) and peptide YY (PYY), key regulators of central appetite control with therapeutic relevance to obesity. Here, we show that butyrate, a metabolite derived from fermentation of dietary fibre and an FFAR2 agonist, stimulates a PYY-biased profile in a human L-cell model at the transcriptional, morphological and secretory level via an FFAR2-Gai axis that does not require dynamin-dependent receptor internalization. We observe that butyrate modulates active Notch cascades within a Hes1-GFP mouse organoid model, which are antagonistic to secretory differentiation, and identify butyrate-dependent regulation of late-stage human enteroendocrine maturation markers, NeuroD1 and Pax6. Butyrate-mediated upregulation of Pyy and Pax6 is enhanced by the FFAR2-selective Gai biased allosteric agonist AZ-1729. Our study reveals functions of spatiotemporally regulated butyrate-activated FFAR2 signalling mechanisms that could be pharmacologically amplified to fine-tune L-cell populations in the human colon. Overall design: RNA-seq profiling of mouse colonic organoids at passage 3 +/- butyrate following 48h or 72h of treatment.