Wnt/β‐catenin‐mediated heat exposure inhibits intestinal epithelial cell proliferation and stem cell expansion through endoplasmic reticulum stress

• Published in: Journal of cellular physiology 2020-07, Vol.235 (7-8), p.5613-5627
• Main Authors: Zhou, Jia‐yi, Huang, Deng‐gui, Zhu, Min, Gao, Chun‐qi, Yan, Hui‐chao, Li, Xiang‐guang, Wang, Xiu‐qi
• Format: Article
• Language: English
• Subjects: Activation; Ambient temperature; Animals; Apoptosis; Apoptosis - genetics; beta Catenin - genetics; Caspase; Caspase 3 - genetics; Catenin; Cell Cycle - genetics; Cell differentiation; Cell Differentiation - genetics; Cell growth; Cell injury; Cell proliferation; Cell Proliferation - genetics; Cell viability; Damage; Differentiation; Endoplasmic reticulum; Endoplasmic Reticulum - genetics; endoplasmic reticulum stress; Endoplasmic Reticulum Stress - genetics; Epithelial cells; Epithelial Cells - metabolism; Epithelium; Exposure; Heat; heat exposure; Heat stress; Heat tolerance; High temperature; Hot Temperature - adverse effects; Humans; Injury prevention; Intestinal Mucosa - growth & development; Intestinal Mucosa - metabolism; intestinal stem cell; Intestine; IPEC‐J2; Polycomb Repressive Complex 1 - genetics; Signal transduction; Stem cell transplantation; Stem cells; Stem Cells - metabolism; Swine - genetics; Wnt protein; Wnt Signaling Pathway - genetics; Wnt/β‐catenin pathway
• ISSN: 0021-9541; 1097-4652
• DOI: 10.1002/jcp.29492

Heat stress induced by continuous high ambient temperatures or strenuous exercise in humans and animals leads to intestinal epithelial damage through the induction of intracellular stress response. However, the precise mechanisms involved in the regulation of intestinal epithelial cell injury, especially intestinal stem cells (ISCs), remain unclear. Thereby, in vitro a confluent monolayer of IPEC‐J2 cells was exposed to the high temperatures (39, 40, and 41°C), the IPEC‐J2 cell proliferation, apoptosis, differentiation, and barrier were determined, as well as the expression of GRP78, which is a marker protein of endoplasmic reticulum stress (ERS). The Wnt/β‐catenin pathway‐mediated regenerative response was validated using R‐spondin 1 (Rspo1). And ex‐vivo, three‐dimensional cultured enteroids were developed from piglet jejunal crypt and employed to assess the ISC activity under heat exposure. The results showed that exposure to 41°C for 72 hr, rather than 39°C and 40°C, decreased IPEC‐J2 cell viability, inhibited cell proliferation and differentiation, induced ERS and cell apoptosis, damaged barrier function and restricted the Wnt/β‐catenin pathway. Nevertheless, Wnt/β‐catenin reactivation via Rspo1 protects the intestinal epithelium from heat exposure‐induced injury. Furthermore, exposure to 41°C for 24 hr reduced ISC activity, stimulated crypt‐cell apoptosis, upregulated the expression of GRP78 and caspase‐3, and downregulated the expression of β‐catenin, Lgr5, Bmi1, Ki67, KRT20, ZO‐1, occludin, and claudin‐1. Taken together, we conclude that heat exposure induces ERS and downregulates the Wnt/β‐catenin signaling pathway to disrupt epithelial integrity by inhibiting the intestinal epithelial cell proliferation and stem cell expansion. Heat‐exposure induced endoplasmic reticulum stress blocks the β‐catenin pathway in the intestinal stem cells, resulting in inhibition of the proliferation and differentiation and promotion of cell apoptosis of porcine intestinal epithelial cells. These processes lead to intestinal function impairment, including damage to the intestinal epithelial integrity.