Figure 1.

ATOH1 is required for all secretory lineages in ileum and colon. (A) Immunohistochemistry combined with Alcian blue (AB) and periodic acid–Schiff (PAS) staining of the ileum and colon from transgenic mice Atoh1^GFP/GFP indicates that endogenous ATOH1 is expressed in goblet and Paneth cells. Scale bars: 100 μm. (B) Immunofluorescent analysis of ileum and colon from Atoh1^GFP/GFP mice indicates that endogenous ATOH1 is expressed in all secretory lineages. Goblet cells were labeled by mucin 2 (MUC2). Paneth cells were labeled by lysozyme 1 (LYZ1). Enteroendocrine cells were labeled by chromogranin A (CHGA). (C) Immunofluorescence analysis indicates the expression level of ATOH1 is lower in enteroendocrine (EE) cells compared with goblet and Paneth cells in Atoh1^GFP/GFP mice. (D) Conditional deletion of ATOH1 in the intestinal epithelium was achieved by using Atoh1^lox/lox;VilCre^ERT2 mice. After tamoxifen injection for 3 consecutive days, Alcian blue staining showed that the secretory lineages were nearly absent in both the ileum and colon compared with wild-type control Atoh1^lox/WT;VilCre^ERT2 mice. Scale bars: 100 μm. DAPI, 4′,6-diamidino-2-phenylindole; KO, knockout; WT, wild type.