Purchase this article with an account.
S.P. Sugrue, R. Alpatov, P. Caton; Role of Pinin in the Regulation of E-Cadherin Promoter Activity . Invest. Ophthalmol. Vis. Sci. 2003;44(13):925.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine the means and regulation of cell-cell adhesion of the corneal epithelium, we have focused our investigations on the epithelial cell adhesion-related protein, pinin (Pnn). Previously, we have shown that Pnn, a 140 kDa nuclear and cell adhesion-related phosphoprotein, is involved in the regulation of cell adhesion and may function in epithelial tumor suppression. Upregulation of Pnn resulted in increased levels of E-cadherin and enhanced cell-cell adhesion of epithelial cells. We suggest that the expression of pinin is a key event in the establishment and maintenance of epithelial cell-cell adhesion. Here, we explore the mechanism by which pnn may exert it’s influence on cadherin expression. Methods: Activity E-cadherin promoter in response to Pnn overexpression was measured after co-transfection of pGLA-3-E-cadherin –427+53 and pcDNA3.1-hPnn-myc/His. pCIneo-hPNNGFP construct, hPnn truncation mutant pCIneo-1-421hPnn-GFP which lacks CtBP interaction domain and pcDNA3.1-CtBP-FLag expression vector. To assay Pnn’s ability to repress transcription while tethered to a promoter site, GAL4-SV40-luc pBIND-hPnn-Gal4 and CtBP-Flag-pcDNA3.1 expression vectors were employed. Results: Transient transfections of E-cadherin immediate promoter-luciferase constructs and Pnn expression vectors revealed dose-dependent increase in activity with wt-Pnn constructs. Expression of Pnn-GAL4 constructs resulted in downregulation of reporter activity indicating that when tethered to a promoter site Pnn is capable of transcription. One possible mechanism of Pnn‘s regulation of E-cadherin may be the sequestration of the transcription co-repressor CtBP. CtBP, which binds to Pnn via a conserved PEDLS, is known to be involved in the regulation of E-cadherin promoter activity by interacting with transcriptional repressors. Transfection of cells with Pnn constructs lacking the CtBP interaction domain does not upregulate cadherin. Finally, Pnn overexpression also relieves the ectopic CtBP-mediated repression of E-cadherin promoter. Conclusions: One possible mechanism of Pnn‘s regulation of E-cadherin may be the sequestration of the transcription co-repressor CtBP. CtBP, which binds to Pnn via a conserved PEDLS, is known to be involved in the regulation of E-cadherin promoter activity by interacting with transcriptional repressors. These data lend support to the proposal that pinin plays a pivotal role in epithelial cell–cell adhesion and epitheliogenesis. (Supported by NIH grant EY07883 )
This PDF is available to Subscribers Only