Knockdown of the tetraspan protein epithelial membrane protein-2 inhibits implantation in the mouse

Abstract

The establishment of pregnancy requires a successful molecular interaction between the trophectoderm cells of the blastocyst stage embryo and the endometrial cells of the uterus. These interactions are complex and require synchronous development and coordinated endocrine, paracrine, and autocrine communication. In this study, we demonstrate that the tetraspan protein epithelial membrane protein-2 (EMP2) is involved in these molecular interactions during implantation. EMP2, which is highly expressed in the uterus, translocates from an intracellular location to the apical surface of the endometrial epithelium during the window of implantation and is expressed in decidualized stromal cells. We developed plasmid constructs that utilized either ribozyme-mediated or short hairpin RNA-mediated mechanisms to target endometrial EMP2 mRNA for destruction. These constructs were transfected into the mouse uterus on day 1 of pregnancy using the technique of in vivo reproductive tract gene transfer. Reduction in EMP2 expression by either method resulted in a significant decrease in the number of implantation sites in the treated uterine horns as compared to control horns. These studies indicate a previously unknown function of tetraspan proteins in implantation and could provide a molecular framework for the development of therapeutic modalities for both contraception and fertility.

Regulation of FAK Activity by Tetraspan Proteins: Potential Clinical Implications in Cancer

“…Both in vitro and in vivo studies suggest that EMP2 translocates from an intracellular location to the apical surface of the endometrial epithelium during the window of implantation in the mouse. 57 In line with EMP2 involvement of blastocyst implantation, FAK undergoes dynamic distributional changes during the same time frame. FAK is localized at the site of cell-to-cell contact on day one of pregnancy and expression of FAK is increased in the apical region of the rat uterine luminal epithelium and rat blastocysts, suggesting that FAK facilitates implantation.…”

“…In the uterus, EMP2 increases the surface expression of αvβ3 integrin in the glandular and luminal uterine epithelium, and acute knockdown experiments suggest that EMP2 is required for an efficient endometrialblastocyst interaction. 57,58 In the retinal pigment epithelium, EMP2 was shown to directly bind to FAK as well, leading to FAK activation through increasing FAK phosphorylation at Y397, Y407, Y861, and Y925. 54,59 While the binding sites between EMP2 and FAK have not yet been determined, the FAK N-terminal FERM domain binds to another membrane-associated tetraspan protein, TM4SF5, 60 suggesting that the FERM domain plays a prominent role in regulation of FAK activity with other membrane-associated proteins.…”

Review of the GAS3 Family of Proteins and their Relevance to Cancer

“…67 It has been proposed that its expression is critical for successful implantation as knockdown of EMP2 within the uterus resulted in a significant decrease in the number of implantation sites within the uterine horns. 68 …”

“…68–72 In this way, EMP2 appears to help stabilize select integrins, modulating adhesion onto various extracellular matrices. 70,73 …”

Epithelial membrane protein 2 modulates infectivity of Chlamydia muridarum (MoPn)

“…Specifically, endometrial cell expression of EMP2 is required for endometrial display and function of avb3 integrin involved in blastocyst interaction. [17,18]. Thus, expression of EMP2 in epithelial cells can play an important role in the trafficking and organization of multipartite protein complexes that are critical for cellecell interaction.…”