Uterine Endometrial Reprogramming during Early Pregnancy is Accompanied by Distinct Spatiotemporal Expression Patterns of Basement Membrane Components

Uterine endometrium undergoes decidualization, a tissue reprogramming process, in response to blastocyst implantation in mice. During this process, stromal cells acquire epithelial‐like behaviors including expressing basement membrane (BM), a specialized form of extracellular matrix that influences epithelial cell identity and behaviors. The assembly and function of BM during decidualization is unknown. In this study, we investigated uterine expression and compartmentalized localization of BM components: classical components collagen IV and laminin, recently identified component peroxidasin, and a putative component Good pasture antigen‐binding protein (GPBP), in the mouse uterus during early pregnancy. Electron microscopic investigation revealed: 1) a smooth continuous layer of BM in between the epithelial and stromal layers of the preimplantation endometrium; and 2) interrupted, uneven, and thickened BM within the pericellular space of the post implantation decidua. Quantification of mRNA levels by qPCR showed changed in expression levels that were complemented by immunofluorescence localization of collagen IV, laminin, peroxidasin, and GPBP. Novel observations of BM‐associated and distinct expression patterns of the four components suggest collective pericellular functions as well as individual functions of the components in the peri implantation uterus and decidua.Support or Funding InformationThis work was supported by National Institutes of Health Grants F31 CA165787‐03 (to C.R.J.), R25 DK096999 (to B.G.H. for S.P. and T.B.), R01 HD044741 (to B.C.P.), and R01 DK018381 (to B.G.H). This study was also supported by RT2014‐2415‐1 / Prometeo II ‐2014‐048 (to J.S).