Endometrial epithelial cells undergo dramatic remodeling during the peri-implantation period. Such changes include alterations in cell-cell adhesions, in cell-matrix interactions, modified apical-basal polarity, and, in some species, cell-cell fusion. We have documented the expression of an mRNA encoding a transmembrane protein rbMDC9, a member of the ADAMs gene family with potential cell binding, cell-matrix interactions and fusogenic properties. RbMDC9 expression is up-regulated in rabbit endometrium during hormonal preparation for implantation, and expression is further augmented by blastocysts. Preliminary evidence suggests a similar up-regulation in mouse and human uteri. We will test the hypothesis that MDC9 in rabbits serve as an integrin-binding adhesion molecule between epithelial cells and, in doing so, also functions in the redistribution of junction and cytoskeletal proteins. Furthermore, we hypothesize that ADAMs family proteins participate in cell-matrix interactions and in the fusions between adjacent epithelial cells and between trophoblast and epithelial cells during implantation, and in the ectopic attachment and invasion of endometrial tissue during endometriosis.
Aim of the project will be 1) to determine if domain specific-targeting and post-translational processing regulate the function of epithelial cell rbMDC9 in peri-implantation-stage endometrium, 2) to determine if rbMDC9 ligand interactions are required for uterine epithelial junction or cytoskeletal protein modifications during implantation, 3) to define the function of rbMDC9 in implantation-specific cell-cell adhesion and/or fusion processes, and determine whether its expression of processing are regulated by blastocysts in vitro, and 4) to determine if MDC9 is expressed in a cycle-specific pattern in endometrium of women with and without endometriosis, and to analyze its regulation and potential roles in the adhesion and invasion of ectopic endometrium in an experimental model of endometriosis.
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