Claudin 7 is reduced in uterine epithelial cells during early pregnancy in the rat

• Published in: Histochemistry and cell biology 2013-04, Vol.139 (4), p.583-593
• Main Authors: Poon, Connie E., Madawala, Romanthi J., Day, Margot L., Murphy, Christopher R.
• Format: Article
• Language: English
• Subjects: Animal reproduction; Animals; Biochemistry; Biomedical and Life Sciences; Biomedicine; Blastocyst; Cell Biology; Cellular biology; Claudins - metabolism; Developmental Biology; Embryo Implantation; Endometrium - cytology; Endometrium - metabolism; Epithelial Cells - metabolism; Epithelium - metabolism; Estrogens; Estrogens - metabolism; Female; Hormones; Original Paper; Ovary - metabolism; Pregnancy; Rats; Rats, Wistar; Rodents; Uterus - metabolism
• ISSN: 0948-6143; 1432-119X
• DOI: 10.1007/s00418-012-1052-y

The non-receptive uterine luminal epithelium forms an intact polarised epithelial barrier that is refractory to blastocyst invasion. During implantation, organised dismantling of this barrier leads to a receptive state promoting blastocyst attachment. Claudins are tight junction proteins that increase in the uterine epithelium at the time of implantation. Claudin 7 is a member of this family but demonstrates a basolateral localisation pattern that is distinct from other claudins. The present study investigated the localisation, abundance and hormonal regulation of claudin 7 to elucidate a role for the protein during implantation. The results showed that claudin 7 demonstrates a distinct basal and lateral localisation in the uterine luminal and glandular epithelium throughout early pregnancy. On day 1, claudin 7 is abundantly present in response to ovarian estrogen. At the time of implantation, claudin 7 decreases in abundance. This decrease is not dependent on blastocyst presence, as shown by results in pseudopregnant animals. We propose that claudin 7 mediates intercellular adhesions in the uterine epithelium and also may be responsible for stabilising adhesion proteins at the basolateral cell surface. Thus, claudin 7 may function under the maintenance of the uterine luminal epithelial barrier, in the non-receptive state preventing implantation from occurring.