B3galt5 regulates obesity and insulin resistance by maintaining the intestinal integrity as a novel PXR target gene

Pregnane X receptor (PXR), a xenobiotic receptor involved in drug metabolism, has been reported to regulate lipid and glucose metabolism. The intestine tract is the first inner barrier of the body, which dysfunction contributes to the development of metabolic disorders. However, the role of intestinal PXR in metabolic diseases remains largely unknown. In this study, we showed that activation of PXR by tributyl citrate (TBC), an intestinal-selective agonist of PXR, improved high fat diet (HFD)-induced obesity and insulin resistance. The metabolic benefit of intestinal PXR activation was associated with upregulation of β-1,3 galactosyltransferase 5 (B3galt5). Our results revealed that B3galt5 is mainly expressed in the intestine and is a direct transcriptional target of PXR. Whole-body and intestine-specific knockout of B3galt5 exacerbated HFD-induced obesity, insulin resistance and inflammation. Mechanistically, B3galt5 is essential to maintain the integrity of intestinal mucus barrier. Ablation of B3galt5 impaired the O-glycosylation of mucin2, destabilized the mucus layer, and increased the permeability of intestinal barrier. Furthermore, B3galt5 deficiency abolished the beneficial effect of intestinal PXR activation on metabolic disorders. Our results suggested the intestinal-selective activation of PXR regulated B3galt5 expression holds an important role in maintaining metabolic homeostasis, making it a potential therapeutic strategy in obesity.