Pinin modulates expression of an intestinal homeobox gene, Cdx2, and plays an essential role for small intestinal morphogenesis

• Published in: Developmental biology 2010-09, Vol.345 (2), p.191-203
• Main Authors: Joo, Jeong-Hoon, Taxter, Timothy J., Munguba, Gustavo C., Kim, Yong H., Dhaduvai, Kanthi, Dunn, Nicholas W., Degan, William J., Oh, S. Paul, Sugrue, Stephen P.
• Format: Article
• Language: English
• Subjects: Animals; beta Catenin - genetics; beta Catenin - metabolism; Cdx2; CDX2 Transcription Factor; Cell Adhesion Molecules - genetics; Cell Adhesion Molecules - metabolism; Embryo, Mammalian - metabolism; Genes, Homeobox; Homeodomain Proteins - genetics; Homeodomain Proteins - metabolism; Intestine, Small - growth & development; Mice; Morphogenesis - genetics; Nuclear Proteins - genetics; Nuclear Proteins - metabolism; Pinin; Signal Transduction; Small intestine; TCF Transcription Factors - genetics; TCF Transcription Factors - metabolism; Transcription Factors - genetics; Transcription Factors - metabolism; Up-Regulation; Villi; Wnt Proteins - genetics; Wnt Proteins - metabolism; Wnt signaling; β-catenin
• ISSN: 0012-1606; 1095-564X
• DOI: 10.1016/j.ydbio.2010.07.009

Pinin (Pnn), a nuclear speckle-associated protein, has been shown to function in maintenance of epithelial integrity through altering expression of several key adhesion molecules. Here we demonstrate that Pnn plays a crucial role in small intestinal development by influencing expression of an intestinal homeobox gene, Cdx2. Conditional inactivation of Pnn within intestinal epithelia resulted in significant downregulation of a caudal type homeobox gene, Cdx2, leading to obvious villus dysmorphogenesis and severely disrupted epithelial differentiation. Additionally, in Pnn-deficient small intestine, we observed upregulated Tcf/Lef reporter activity, as well as misregulated expression/distribution of β-catenin and Tcf4. Since regulation of Cdx gene expression has been closely linked to Wnt/β-catenin signaling activity, we explored the possibility of Pnn's interaction with β-catenin, a major effector of the canonical Wnt signaling pathway. Co-immunoprecipitation assays revealed that Pnn, together with its interaction partner CtBP2, a transcriptional co-repressor, was in a complex with β-catenin. Moreover, both of these proteins were found to be recruited to the proximal promoter area of Cdx2. Taken together, our results suggest that Pnn is essential for tight regulation of Wnt signaling and Cdx2 expression during small intestinal development.