Palmatine ameliorates intestinal epithelial barrier injury in ulcerative colitis via targeting enolase 3

Disruption of intestinal epithelial barrier is the major pathological characteristics of ulcerative colitis (UC). Palmatine (PAL) is a natural isoquinoline alkaloid derived from various traditional Chinese herbal medicines. The present study reported that PAL exerted anti-UC effects via protecting against intestinal epithelial cell injury and alleviating intestinal barrier dysfunction. In dextran sulfate sodium (DSS)-induced mice UC model, PAL alleviated symptoms like weight loss, diarrhea, rectal bleeding, colon shortening, and colon damage. In particular, PAL reduced intestinal permeability and FITC-dextran leakage, prevented the loss of goblet cells, increased expressions of mucins, tight junction (TJ) and adherens junction (AJ) proteins. In HCoEpiC cells, PAL promoted cell proliferation, inhibited apoptosis, improved cell barrier function by reducing the penetration of FITC-dextran across the cell barrier and increasing transepithelial electrical resistance. By using the Cellular Thermal Shift Assay (CETSA) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) proteomics technology, we identified Enolase 3 (ENO3) as the direct molecular target of PAL. CETSA, DARTS, and molecular docking confirmed PAL binds ENO3 and upregulates its expression. The protective effects of PAL on intestinal inflammation and barrier dysfunction were abolished when co-treated with ENOblock (an ENO3 inhibitor) or ENO3 knockdown by small interfering RNA, confirming that PAL alleviates UC by targeting ENO3. Mechanistically, Seahorse assays and ATP detection confirmed that PAL inhibits intestinal epithelial cell glycolysis to alleviate UC symptoms. In conclusion, our findings identify PAL as a novel phytochemical that displays anti-UC efficacy via targeting ENO3, endorsing its potential utility as a therapy for treatment of UC.