miR-222 Represses Expression of Zipcode Binding Protein-1 and Phospholipase C-γ1 in Intestinal Epithelial Cells.

Both zipcode binding protein-1 (ZBP1) and phospholipase C-γ1 (PLC-γ1) are intimately involved in many aspects of early intestinal mucosal repair after acute injury, but the exact mechanisms that control their cellular abundances remain largely unknown. The present study shows that microRNA 222 (miR-222) interacts with the mRNAs encoding ZBP1 and PLC-γ1 and thus regulates ZBP1 and PLC-γ1 expression in intestinal epithelial cells (IECs). The biotinylated miR-222 specifically bound to the ZBP1 and PLC-γ1 mRNAs in IECs. Ectopically expressed miR-222 precursor destabilized the ZBP1 and PLC-γ1 mRNAs and consequently lowered the levels of cellular ZBP1 and PLC-γ1 proteins. Conversely, decreasing the levels of cellular miR-222 by transfection with its antagonism increased the stability of the ZBP1 and PLC-γ1 mRNAs and increased the levels of ZBP1 and PLC-γ1 proteins. Overexpression of miR-222 also inhibited cell migration over the wounded area, which was partially abolished by overexpressing ZBP1 and PLC-γ1. Furthermore, prevention of the increased levels of ZBP1 and PLC-γ1 in the miR-222-silenced cells by transfection with specific small interfering RNAs (siRNAs) targeting ZBP1 and PLC-γ1 mRNAs inhibited cell migration after wounding. These findings indicate that induced miR-222 represses expression of ZBP1 and PLC-γ1 at the posttranscription level, thus inhibiting IEC migration during intestinal epithelial restitution after wounding.