The Role of Extracellular Matrix Metalloproteinase Inducer (EMMPRIN) in the Regulation of Bovine Endometrial Cell Functions1

Abstract

Extracellular matrix metalloproteinase inducer (EMMPRIN) is a cell surface glycoprotein that stimulates the production of several matrix metalloproteinases (MMPs) for tissue remodeling. Previously, we detected EMMPRIN in the bovine endometrium, and it is mainly expressed in the luminal and glandular epithelium whereas MMPs are expressed in the underlying stroma. From this expression pattern, we hypothesized that EMMPRIN may regulate stromal MMPs in endometrial cell functions. To test this hypothesis, a coculture of epithelial and stromal cells was performed using a transwell system. In the coculture, epithelial cells were cultured on the insert membrane and stromal cell on the surface of well plates. Expression of stromal MMP-2 and MMP-14 was significantly higher in coculture with epithelial cell. Further, with the addition of anti-EMMPRIN antibody into the epithelial cell compartment, the expression of stromal EMMPRIN and MMP-2 and MMP-14 was decreased. To identify the active site of EMMPRIN for the augmentation of MMPs, EMMPRIN synthetic peptides that correspond to the extracellular loop domain-I (EM1, EM2, EM3, and EM4) were added into the epithelial cell compartment, and only EM2 at a higher dose interfered with EMMPRIN-mediated expression of MMP-14. Next, we examined the effects of progesterone and/or estrogen on the expression of EMMPRIN, MMP-2, and MMP-14. Progesterone (300 nM) significantly stimulated the expression of EMMPRIN but had no effects on any of the MMPs. These results suggest that EMMPRIN derived from epithelial cells regulates MMPs in the endometrium under progesterone-rich conditions and may thereby modulate bovine endometrial cell functions during gestation.