Involvement of VCAM1 in the bovine conceptus adhesion to the uterine endometrium

• DOI: 10.1530/rep-13-0655
• Publication Date: 2014-05-07T02:10:37Z
• Authors: Rulan Bai; Hanako Bai; Mariko Kuse; Atsushi Ideta; Yoshito Aoyagi; Hiroshi Fujiwara; Kiyoshi Okuda; Kazuhiko Imakawa; Toshihiro Sakurai
• Keywords: 0301 basic medicine; Reverse Transcriptase Polymerase Chain Reaction; Integrin alpha4; Blotting, Western; Uterus; Gene Expression Regulation, Developmental; Cell Communication; Real-Time Polymerase Chain Reaction; Coculture Techniques; Epithelium; Trophoblasts; Immunoenzyme Techniques; Endometrium; 03 medical and health sciences; Blastocyst; Cell Adhesion; Animals; Cattle; Female; Embryo Implantation; RNA, Messenger; Cells, Cultured

Following bidirectional communication, the conceptus and the uterine epithelium must establish a proper cell–cell interaction, resulting in the progression of implantation processes. To clarify the mechanism of conceptus attachment to the uterine endometrium, we studied whether vascular cell adhesion molecule (VCAM1) was expressed in bovine conceptuses or endometrium during the peri-attachment period. UterineVCAM1expression was minimal in day 17 (day 0=day of estrus) cyclic and pregnant animals, but increased between days 20 and 22 of pregnancy. In the intercaruncular regions, VCAM1 protein was localized to the luminal and glandular epithelia, whereas in the caruncular regions, VCAM1 protein was detected in the stroma and endothelia of the uterine endometrium. In cultured endometrial epithelial cells (EECs),VCAM1expression was up-regulated when treated with uterine flushings or growth factor and further increased when EECs were cocultured with bovine trophoblast CT1 cells.VCAM1expression in CT1 cells was also up-regulated with the use of uterine flushings, and further increased when these cells were cocultured with EECs. Expression of VCAM1 receptor, integrin α 4 (ITGA4) mRNA, increased significantly in day 22 conceptuses. In day 22 pregnant uteri, VCAM1 protein was found in both EECs and conceptuses, but ITGA4 was localized only to trophoblasts. These observations indicate that cell–cell interactions between conceptuses and uterine epithelial cells are required for sufficient VCAM1 and ITGA4 expression in the bovine species and suggest that uterine VCAM1 and conceptus ITGA4 play a role in the establishment of conceptus adhesion to the uterine endometrium.