MicroRNA-7 Modulates CD98 Expression during Intestinal Epithelial Cell Differentiation

Hang Thi Thu Nguyen,Guillaume Dalmasso,Yutao Yan,Hamed Laroui,Stephanie Dahan,Lloyd Mayer,Shanthi V Sitaraman,Didier Merlin

doi:10.1074/jbc.m109.057141

Hang Thi Thu Nguyen, Guillaume Dalmasso + Show 6 more

Open Access

https://doi.org/10.1074/jbc.m109.057141

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Abstract

The transmembrane glycoprotein CD98 regulates multiple cellular functions, including extracellular signaling, epithelial cell adhesion/polarity, amino acid transport, and cell-cell interactions. MicroRNAs post-transcriptionally regulate gene expression, thereby functioning as modulators of numerous cellular processes, such as cell differentiation, proliferation, and apoptosis. Here, we investigated if microRNAs regulate CD98 expression during intestinal epithelial cell differentiation and inflammation. We found that microRNA-7 repressed CD98 expression in Caco2-BBE cells by directly targeting the 3'-untranslated region of human CD98 mRNA. Expression of CD98 was decreased, whereas that of microRNA-7 was increased in well-differentiated Caco2-BBE cells compared with undifferentiated cells. Undifferentiated crypt cells isolated from mouse jejunum showed higher CD98 levels and lower levels of mmu-microRNA-706, a murine original microRNA candidate for CD98, than well-differentiated villus cells. Importantly, microRNA-7 decreased Caco2-BBE cell attachment on laminin-1, and CD98 overexpression recovered this inhibition, suggesting that microRNA-7 modulates epithelial cell adhesion to extracellular matrix, which in turn could affect proliferation and differentiation during the migration of enterocytes across the crypt-villus axis, by regulating CD98 expression. In a pathological context, the pro-inflammatory cytokine interleukin 1-beta increased CD98 expression in Caco2-BBE cells by decreasing microRNA-7 levels. Consistent with the in vitro findings, microRNA-7 levels were decreased in actively inflamed Crohn disease colonic tissues, where CD98 expression was up-regulated, compared with normal tissues. Together, these results reveal a novel mechanism underlying regulation of CD98 expression during patho-physiological states. This study raises microRNAs as a promising target for therapeutic modulations of CD98 expression in intestinal inflammatory disorders.

Highlights

Expression of CD98 Is Decreased during the Differentiation of Intestinal Epithelial Cells— CD98 has been shown to be located in the basolateral membrane of well-differentiated IEC [1], its expression during IEC differentiation is not yet investigated
We first assessed the expression of human CD98 in intestinal epithelial Caco2-BBE cells at different time points post-plating
Caco2-BBE cell differentiation during the conventional culture period was evaluated by measuring the trans-epithelial resistance (TER) of the cells in real-time using the electric cell-substrate impedance sensing (ECIS) technique

Summary

Introduction

Real-time RT-PCR and Western blot analyses showed higher levels of mouse (m) CD98 expression in undifferentiated crypt cells compared with well-differentiated villus cells (Fig. 1, E and F). Expression levels of hsa-miR-626, used as a control miRNA, in undifferentiated and well-differentiated Caco2-BBE cells were not significantly different (Fig. 2B).

Results

Conclusion