Abstract
The ErbB4 receptor tyrosine kinase is induced by inflammation in intestinal epithelial cells (IECs). Its ligand, NRG4, promotes survival signaling in colonocytes. However, the effects of ErbB4 loss on the small intestine or the intestinal stem cell (ISC) niche have not been defined. We asked whether ErbB4 deletion enhances tumor necrosis factor (TNF)‐induced apoptosis, and if it compromises the ISC niche. METHODS: Epithelial enteroid cultures from ileal crypts of ErbB4flox/flox (WT) and ErbB4flox/flox; Villin‐Cre (ErbB4KOIE) mice were given TNF (200 ng/ml) daily for 5 days, then expression of Paneth cell (Lyz1) and ISC (Lgr5) markers were tested by qPCR. WT and ErbB4KOIE mice were injected with 250 μg/kg TNF; after 24 h, ileums were fixed, sectioned, and apoptosis detected by In Situ Oligo Ligation (ISOL). RESULTS: ErbB4KOIE enteroids were dysmorphic, with 64% fewer buds/enteroid than WT, and had lower expression of Lyz1 (57% reduction, p<0.05) and Lgr5 (75% reduction, p<0.01). ErbB4‐null enteroids were highly sensitive to TNF, losing all crypt bud architecture after exposure. In vivo, ErbB4KOIE mice had increased TNF‐induced ileal epithelial apoptosis (1.8‐fold increase in ISOL+ cells, p=0.001) than WT. CONCLUSIONS: ErbB4 loss exacerbates TNF‐induced IEC death both in vivo and in vitro. This is associated with loss of PC and ISC markers, suggesting a role for ErbB4 in regulating the ISC niche.
Grant Funding Source: Supported by NIH grant R01DK095004 and ACS grant 124678‐RSG‐13‐199‐01‐DDC