T‐bet Regulates Ion Channels and Transporters and Induces Apoptosis in Intestinal Epithelial Cells

Abstract T‐bet, encoded by TBX21, is extensively expressed across various immune cell types, and orchestrates critical functions in their development, survival, and physiological activities. However, the role of T‐bet in non‐immune compartments, notably the epithelial cells, remains obscure. Herein, a Tet‐O‐T‐bet transgenic mouse strain is generated for doxycycline‐inducible T‐bet expression in adult animals. Unexpectedly, ubiquitous T‐bet overexpression causes acute diarrhea, intestinal damage, and rapid mortality. Cell‐type‐specific analyses reveal that T‐bet‐driven pathology is not attributable to its overexpression in CD4⁺ T cells or myeloid lineages. Instead, inducible T‐bet overexpression in the intestinal epithelial cells is the critical determinant of the observed lethal phenotype. Mechanistically, T‐bet overexpression modulates ion channel and transporter profiles in gut epithelial cells, triggering profound fluid secretion and subsequent lethal dehydration. Furthermore, ectopic T‐bet expression enhances gut epithelial cell apoptosis and markedly suppresses colon cancer development in xenograft models. Collectively, the findings unveil a previously unrecognized role of T‐bet in intestinal epithelial cells for inducing apoptosis, diarrhea, and local inflammation, thus implicating its potential as a therapeutic target for the treatment of cancer and inflammatory diseases.