Wnt signaling promotes gastric chief cell identity and mucosal repair after injury

The gastric mucosa is lined with a simple columnar epithelium that is renewed by gastric stem cells throughout lifespan. Wnt signaling is an essential niche pathway for stem cell maintenance and cellular differentiation, and pathway activation is associated with hyperproliferative gastric diseases. A Wnt signaling gradient is established along the gastric gland axis, with highest signaling at the base where chief cells (CC) are located. Despite being a key regulator of gastric stem cell function, it is not known how Wnt signaling regulates CC function. We hypothesized that Wnt signaling is essential to maintain CC identity. To study Wnt function in CC, we used a CC-specific genetic driver mouse (GIF-rtTA; TetO-Cre; ROSA-mTmG) to inhibit canonical Wnt signaling by crossing to mice with a floxed b-catenin allele (Ctnnb1fl/fl). The GIF-rtTA; TetO-Cre; ROSA-mTmG; Ctnnb1fl/fl mice (termed Ctnnb1∆CC) showed effective loss of b-catenin protein in CC following doxycycline treatment compared to doxycycline-treated control mice (Gif-rtTA; TetO-Cre; mTmG). Lineage tracing was used to determine the fate of Wnt-depleted CC by imaging for GFP. Wnt-depleted CC were maintained at the gland base in Ctnnb1∆CC mice, demonstrating that Wnt signaling is not required for cell survival. However, immunostaining showed loss of the CC-specific marker gastric intrinsic factor (GIF). Remarkably, these cells at the gland base instead activated markers of other gastric cell types, including surface mucous cells (MUC5AC, UEA-1) and neck cells (GSII, TFF2). Furthermore, some b-catenin-deleted CC were proliferating (EdU) and GFP-lineage stripes that extended the length of the gastric gland were observed, suggesting that after loss of canonical Wnt signaling, CC remodel to take on a progenitor cell identity. To test whether the Wnt-regulated changes to CC identity are epithelial cell specific, we studied organoids derived from uninduced Ctnnb1∆CC mice and found that doxycycline-treated organoids showed decreased CC marker (Gif, Mist1, Lgr5) and increased surface cell marker (Muc5AC, Tff2, Tff1) mRNA abundance. Besides secreting digestive enzymes, CC can also function as reserve stem cells, transforming to proliferating regenerative cells after injury. We therefore tested the role of CC Wnt signaling after injury induced by high dose tamoxifen treatment (HDT). Notably, HDT accelerated the expansion of GFP-lineage stripes and increased Edu+ cells in b-catenin-deleted CC, demonstrating that Wnt is not required for injury-induced CC proliferation. However, 1-month post HDT injury, in contrast to the control, the Ctnnb1∆CC mouse gastric mucosa had not regenerated, showing hyperproliferation and distorted glandular structure. Together our findings suggest that canonical CC Wnt signaling is required to maintain cell identity during homeostasis, and to repair the gastric mucosa after injury. This project was funded by R01DK126451 and R01DK142725 (LCS), and T32DK094775 (CQH). This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.