Divergent roles of estrogen receptor subtypes in regulating estrogen-modulated colonic ion transports and epithelial repair

Although it was described previously for estrogen (E(2)) regulation of intestinal epithelial Cl(−) and HCO(3)(−) secretion in sex difference, almost nothing is known about the roles of estrogen receptor (ER) subtypes in regulating E(2)-modulated epithelial ion transports and epithelial restitution. Here, we aimed to investigate ERα and ERβ subtypes in the regulation of E(2)-modulated colonic epithelial HCO(3)(−) and Cl(−) secretion and epithelial restitution. Through physiological and biochemical studies, in combination of genetic knockdown, we showed that ERα attenuated female colonic Cl(−) secretion but promoted Ca(2+)-dependent HCO(3)(−) secretion via store-operated calcium entry (SOCE) mechanism in mice. However, ERβ attenuated HCO(3)(−) secretion by inhibiting Ca(2+)via the SOCE and inhibiting cAMP via protein kinases. Moreover, ERα but not ERβ promoted epithelial cell restitution via SOCE/Ca(2+) signaling. ERα also enhanced cyclin D1, proliferating cell nuclear antigen, and β-catenin expression in normal human colonic epithelial cells. All ERα-mediated biological effects could be attenuated by its selective antagonist and genetic knockdown. Finally, both ERα and ERβ were expressed in human colonic epithelial cells and mouse colonic tissues. We therefore conclude that E(2) modulates complex colonic epithelial HCO(3)(−) and Cl(−) secretion via ER subtype-dependent mechanisms and that ERα is specifically responsible for colonic epithelial regeneration. This study provides novel insights into the molecular mechanisms of how ERα and ERβ subtypes orchestrate functional homeostasis of normal colonic epithelial cells.