IPR-dependent Ca signaling in the endoplasmic reticulum is required for deoxynivalenol-induced intestinal stem cell injury.

Deoxynivalenol (DON), a prevalent mycotoxin contaminant in cereals, compromises intestinal homeostasis by inducing organelle dysfunction, particularly in the endoplasmic reticulum (ER). Despite the critical role of ER stress in intestinal pathology, the precise mechanisms by which DON-induced ER dysfunction affects intestinal stem cell (ISC) fate commitment remain unclear. Here, we demonstrate that acute exposure to DON disrupts jejunal epithelial architecture and impairs barrier integrity in piglets by suppressing ISC proliferation and inhibiting differentiation of epithelial lineages along the crypt-villus axis. Consistently, DON reduces the ex vivo expansion capacity of jejunal crypt-derived intestinal organoids. Mechanistically, DON triggers endoplasmic reticulum stress (ERS), marked by elevated glucose-regulated protein 78 (GRP78) and phosphorylated eukaryotic translation initiation factor 2 subunit alpha (p-eIF2α), and promotes IP receptor (IPR)-dependent calcium efflux from the ER, leading to enhanced cytoplasmic Ca signaling. This calcium dysregulation activates the calmodulin-dependent protein kinase II/calcineurin/nuclear factor of activated T cells, cytoplasmic 1 (CaMKII/CaN/NFATC1) -pathway, which suppresses ISC proliferation and differentiation. Pharmacological inhibition of ERS using 4-phenylbutyric acid (4-PBA) reduces GRP78 expression and restores epithelial cell proliferation. Importantly, selective blockade of ER-localized IPRs-rather than plasma membrane transient receptor potential cation channel subfamily V member 6 (TRPV6) channels-effectively attenuates Ca signaling and preserves intestinal epithelial viability. These findings identify IPR-mediated ER Ca signaling as a critical mechanistic link between DON-induced ERS and ISC injury. Modulation of this ER Ca signaling pathway presents a promising therapeutic approach for alleviating DON-associated intestinal damage in both human and animal populations.