Piezo1‐mediated unfolded protein response in goblet cells regulates intestinal mucus barrier homeostasis through the Ca 2 + –IRE1α–XBP1 pathway

BACKGROUND: Our previous study revealed that Piezo1 in colonic goblet cells senses mechanical stimuli to regulate the production and secretion of MUC2, but the underlying mechanism remains unclear. Altered endoplasmic reticulum function and the unfolded protein response (UPR), which are critical for MUC2 protein folding and secretion, were observed in goblet cell-specific Piezo1 knockout mice. This study aimed to investigate whether and how Piezo1 in goblet cells modulates mucus barrier function by regulating the UPR. METHODS: In vitro, LS174T cells were subjected to orbital shaking to simulate fluid shear stress (FSS) stimulation. The expression of UPR-related molecules and MUC2 was detected using real-time PCR, Western blotting, and immunofluorescence staining in the presence or absence of Piezo1 and UPR inhibition. In vivo, goblet cell-specific Piezo1 knockout (cKO) mice were treated with dextran sulphate sodium (DSS) and water avoidance stress (WAS). We analysed changes in goblet cell morphology, mucus layer thickness, UPR-related protein expression and ER structure. In addition, DSS-induced colitis mice were intraperitoneally injected with Yoda1 to activate Piezo1, and alterations in pathological structures and mucus layer thickness were subsequently evaluated. RESULTS: Compared with PERK or ATF6, FSS activated PIEZO1 and promoted calcium influx, thereby maintaining ER calcium homeostasis and selectively activating the IRE1α-XBP1 signalling pathway. This cascade facilitated MUC2 production, whereas pharmacological inhibition of PIEZO1 or IRE1α expression significantly abolished these effects. Compared with WT mice, cKO mice exhibited aggravated mucus barrier impairment, downregulated IRE1α-XBP1 and aggravated ER swelling under DSS and WAS. In contrast, pharmacological activation of Piezo1 via Yoda1 treatment restored intestinal mucus layer thickness and ameliorated colitis in DSS mice. CONCLUSIONS: Piezo1 senses mechanical stimulation to maintain ER calcium homeostasis and modulates the UPR via the IRE1α-XBP1 pathway, thereby facilitating MUC2 production in goblet cells and maintaining intestinal mucosal barrier homeostasis. KEY POINTS: -IRE1α-XBP1 signaling axis controls Mucin2 synthesis and production to maintain intestinal mucus barrier integrity. Pharmacological activation of Piezo1 by Yoda1 rescues mucus barrier defects, providing a potential therapeutic strategy for gastrointestinal mucosal injury.