Abstract

G protein-coupled estrogen receptor (GPER) might be involved in ulcerative colitis (UC), but the direct effect of GPER on UC is still unclear. We used male C57BL/6 mice to establish the acute colitis model with administration of dextran sulfate sodium (DSS), and explored the effect of GPER on acute colitis and its possible mechanism. The selective GPER agonist G-1 inhibited weight loss and colon shortening, and decreased the Disease Activity Index for colitis and histological damage in mice with colitis. All of these effects were prevented by a selective GPER blocker. G-1 administration prevented the dysfunction of tight-junction proteins expression and goblet cells in colitis model, thus inhibited the increase in mucosal permeability in colitis-suffering mice significantly. GPER activation reduced expression of glucose-regulating peptide-78 and anti-CCAAT/enhancer-binding protein homologous protein, and attenuated the three arms of the unfolded protein response in colitis. G-1 therapy inhibited the increase of cleavage caspase-3 and TUNEL positive cells in colonic crypts in the colitis model, increased the number of Ki67- and bromodeoxyuridine-positive cells in crypts, and reversed the decrease of cyclin D1 and cyclin B1 expression in colitis, indicating its protective effect on crypt cell. In cultured CCD841 cells G-1 treatment fought against cell injury induced by endoplasmic reticulum stress. These findings demonstrate that GPER activation prevents colitis by protecting the colonic crypt cells, which is associated with inhibition of endoplasmic reticulum stress.

Significance Statement We demonstrate that GPER activation prevents the DSS-induced acute colitis by protecting the crypt cells, showing that it inhibited the crypt cell apoptosis and protected proliferation of crypt cell, which resulted in protection of the intestinal mucosal barrier. This protective effect was achieved (at least in part) by inhibiting ERS. Mucosal healing is regarded to be a key therapeutic target for colitis, and GPER is expected to become a new therapeutic target for colitis.