The homeodomain transcription factors Cdx1 and Cdx2 induce E-cadherin adhesion activity by reducing β- and p120-catenin tyrosine phosphorylation

Abstract

The homeodomain transcription factors Cdx1 and Cdx2 are regulators of intestine-specific gene expression. They also regulate intestinal cell differentiation and proliferation; however, these effects are poorly understood. Previously, we have shown that expression of Cdx1 or Cdx2 in human Colo 205 cells induces a mature colonocyte morphology characterized by the induction of a polarized, columnar shape with apical microvilli and strong cell-cell adhesion. To elucidate the mechanism underlying this phenomenon, we investigated the adherens junction complex. Cdx1 or Cdx2 expression reduced Colo 205 cell migration and invasion in vitro, suggesting a physiologically significant change in cadherin function. However, Cdx expression did not significantly effect E-cadherin, alpha-, beta-, or gamma-catenin, or p120-catenin protein levels. Additionally, no alteration in their intracellular distribution was observed. Cdx expression did not alter the coprecipitation of beta-catenin with E-cadherin; however, it did reduce p120-catenin-E-cadherin coprecipitation. Tyrosine phosphorylation of beta- and p120-catenin is known to disrupt E-cadherin-mediated cell adhesion and is associated with robust p120-catenin/E-cadherin interactions. We specifically investigated beta- and p120-catenin for tyrosine phosphorylation and found that it was significantly diminished by Cdx1 or Cdx2 expression. We restored beta- and p120-catenin tyrosine phosphorylation in Cdx2-expressing cells by knocking down the expression of protein tyrosine phosphatase 1B and noted a significant decline in cell-cell adhesion. We conclude that Cdx expression in Colo 205 cells induces E-cadherin-dependent cell-cell adhesion by reducing beta- and p120-catenin tyrosine phosphorylation. Ascertaining the mechanism for this novel Cdx effect may improve our understanding of the regulation of cell-cell adhesion in the colonic epithelium.

Repression of the Desmocollin 2 Gene Expression in Human Colon Cancer Cells Is Relieved by the Homeodomain Transcription Factors Cdx1 and Cdx2

“…1A). The induction of desmosomes by Cdx has been noted by us and others in the past (17,20,21). However, the mechanism by which this occurs remains unknown.…”

“…We noted a profound change in their appearance when Cdx1 or Cdx2 was expressed. Cdx expression induced tight cell clustering and enhanced cell-cell adhesion (17,18). At the ultrastructural level, this is associated with the induction of a polarized, columnar morphology and the development of advanced cell-cell junctions, including adherens, tight, and desmosomal junctions (Fig.…”

“…In the present study, we showed that the intestine-specific transcription factors Cdx1 and Cdx2 directly regulate DSC2 gene expression. Enhanced DSC2 protein levels may contribute to the increased desmosome formation observed after the expression of Cdx1 or Cdx2 in some cell lines (17,18,20,21).…”

“…Cells were all maintained as recommended by the American Type Culture Collection. MIGR1-infected, MIGR-Cdx1 -infected, and MIGR-Cdx2 -infected Colo 205 cells and MIGR-Flag-Cdx2 Colo 205 cells were generated from Colo 205 cells as described (17,18).…”

“…They modulate these diverse processes largely by enhancing the expression of several target genes, including sucrase isomaltase, haephestin, LI-cadherin, claudin2, Bcl2, and KLF4 (11-16). We and others have shown that Cdx1 and Cdx2 can modulate adherens and tight junction activity in intestinal epithelial cells (11,(17)(18)(19); however, regulation of desmosome formation by Cdx remains unexplored.…”