β-Arrestin1 inhibits chemotherapy-induced intestinal stem cell apoptosis and mucositis

The mechanism of chemotherapy-induced gastrointestinal (GI) syndrome (CIGIS) is still controversial, and it is unclear whether chemotherapy induces intestinal stem cell (ISC) apoptosis. beta-Arrestins are regulators and mediators of G protein-coupled receptor signaling in cell apoptosis, division and growth. In this study, we aimed to investigate whether chemotherapy induces ISC apoptosis to contribute to mucositis in CIGIS and whether beta-arrestin1 (beta-arr1) is involved in this apoptosis. Different chemotherapeutic agents were used to generate a CIGIS model. Lgr5-EGFP-IRES-creERT2(+/-) knock-in mice were used as a CIGIS model to investigate ISC apoptosis. beta-arr1 knockout mice were used to determine whether beta-arr1 is involved in the apoptosis in CIGIS. Intestinal histology was performed, the ISC apoptosis was analyzed and the mucosal barrier was examined. The effects of beta-arr1 in apoptosis were investigated in the samples from humans and mice as well as in cell lines. Here, we demonstrate that chemotherapy induced intestinal mucositis by promoting crypt cell apoptosis, especially in Lgr5+ stem cells and Paneth cells but not in goblet cells, epithelial cells or vascular endothelial cells. Furthermore, beta-arr1 deficiency exacerbated the Lgr5+ stem cell apoptosis, but not Paneth cell apoptosis, in CIGIS. In addition, the data showed that beta-arr1 reduced the chemotherapy-induced Lgr5+ stem cell apoptosis by inhibiting endoplasmic reticulum stress-mediated mitochondrial apoptotic signaling. Our study indicates that beta-arr1 inhibits chemotherapy-induced ISC apoptosis to alleviate intestinal mucositis in CIGIS.