Bacterial metabolite S-equol modulates glucagon-like peptide-1 secretion from enteroendocrine L cell line GLUTag cells via actin polymerization

Abstract

S-equol is one of gut bacterial metabolites produced from soybean isoflavone daizein. While S-equol is known to promote glucose-induced insulin secretion from pancreatic β cells, whether S-equol affects glucagon-like peptide-1 (GLP-1) secretion from enteroendoceine L cells remains unclear. Here we assessed the effect of S-equol on GLP-1 secretion from mouse enteroendocrine L cell line GLUTag cells. GLUTag cells expressed GPR30 and estrogen receptors, which are putative S-equol receptors. Application of S-equol induced an increase in intracellular Ca²⁺ levels via GPR30. However, S-equol did not enhance GLP-1 exocytosis, and long-term treatment of S-equol suppressed GLP-1 secretion. Moreover, immunocytochemistry revealed that S-equol increased the density of cortical actin filaments via G_12/13 signaling under GPR30. These data suggest that S-equol prevents GLP-1 secretion as a result of competing regulation between Ca²⁺ mobilization and actin reorganization.

Keywords: Actin reorganization; Bacterial metabolite; Enteroendocrine L cell; Glucagon-like peptide-1; Live-cell imaging; S-equol.