Epithelial Src homology region 2 domain-containing phosphatase-1 restrains intestinal growth, secretory cell differentiation, and tumorigenesis.

Shp-1 (Src homology region 2 domain-containing protein tyrosine phosphatase-1) is a phosphatase that is highly expressed in hematopoietic and epithelial cells. Whereas its function is largely characterized in hematopoietic cells, its role in epithelial cells, such as intestinal epithelial cells (IECs), is not well known. Here, we generated mice with an IEC-specific knockout of Shp-1 (Srchomology region 2 domain-containing phosphatase-1; Shp-1(IEC-KO)). We showed that the loss of epithelial Shp-1 leads to an intestinalomegaly that is associated with an increase in epithelial cell proliferation and size. Histologic analysis demonstrates significant perturbation of the crypt-villus architecture with an apparent increase in the number of goblet and Paneth cells and increased expression of their respective markers {Muc2 (mucin 2), alpha Def, and Sox9 [SRY (sex determining region Y)-box 9]}. Expansion of intermediate cells-common progenitors of goblet and Paneth cell lineages-is also observed in Shp-1(IEC-KO) mice. Although sustained activation of Wnt/beta-catenin and PI3K/Akt/mammalian target of rapamycin signaling is observed, Shp-1(IEC-KO) mice fail to develop any intestinal tumors after 15 mo; however, the loss of Shp-1 in IECs markedly enhances tumor load Apc(Min/+) mice. These findings show a novel role for Shp-1 in the regulation of IEC growth and secretory lineage allocation, possibly via modulation of PI3K/Akt-dependent signaling pathways. Finally, Shp-1 does not function as a classic tumor suppressor gene in the intestinal epithelium.