Endometrial connexin expression in the mare and pig: Evidence for the suppression of cell-cell communication in uterine luminal epithelium

Abstract

This investigation examines the relationship between implantation strategy and gap junction protein expression in uterine endometrium. The pattern of gap junction and connexin protein expression was analyzed in porcine and equine endometrium from cycling and pregnant animals using electron microscopy and immunocytochemistry. Functional analysis of cellcell communication was also monitored by laser cytometry in primary cultures of endometrial epithelial cells. Gap junctions were detected in endometrial stroma of cycling and pregnant animals, which was correlated with immunoreactive Cx43 within stromal fibroblasts and vascular elements. No Cx26, Cx32, or Cx43 immunostaining was detected in luminal endometrial epithelium in either the mare or the pig at any stage of the estrous cycle or pregnancy. In contrast, endometrial glands of the mare exhibited a spatiotemporal pattern of Cx43 expression in the apicolateral plasma membrane which, when present, colocalized with the tight junction-associated protein, ZO-1. Uterine glandular Cx43 expression in mares was present from day 3 postovulation through day 14 of diestrus and until day 23 of pregnancy, whereas Cx43 was absent within uterine glands during seasonal anestrus, estrus, and after day 30 of pregnancy. Primary cultures of equine endometrial epithelial cells expressed both immunoreactive Cx43 and significant gap junction-mediated intercellular communication (GJIC) which was rapidly upregulated by 1.0 mM 8-bromo-cAMP or blocked with 1.0 mM octanol. No GJIC or connexin protein was detected in cultured porcine epithelial cells despite incubation with a variety of agents, including 8-bromo-cAMP, steroid hormones, retinoic acid, and/or prolactin.

Establishment of a new method for isolation and culture of equine endometrial epithelial and stromal cells

“…Isolation and culture of equine endometrial epithelial and/or stromal cells has previously been described only by a handful of authors (Watson et al 1992, Brady et al 1992, 1993, Burghardt et al 1995, Day et al 1998, Buschatz 2007. The morphology of EEC and ESC cultured in this study reveal matchable results compared to the findings in other species (women and animals) (Satyaswaroop et al 1979, Ricketts et al 1983, Zhang et al 1991) and the mare (Watson et al 1992, Buschatz 2007 without the prejudice of the usage of a serum-reduced culture medium.…”

“…However, little was done to isolate and culture equine epithelial glandular cells and stromal cells (Watson et al 1992, Brady et al 1992, 1993, Day et al 1998, Buschatz 2007.…”

Morpho-functional characterization of equine endometrial epithelial cells in vitro – preliminary results

“…Schlüsselwörter: Immunhistologie, Zellkultur, Endometrium, Epithelzellen, Pferd (1992) and Buschatz (2007). Brady et al (1992Brady et al ( , 1993, Burghardt et al (1995) and Day et al (1998) cultivated only equine EEC. All of these studies concerning the EEC generally describe primary cultures.…”

Retinoic acid regulates gap junction intercellular communication in human endometrial stromal cells through modulation of the phosphorylation status of connexin 43

“…Retinoic acid (RA) and other retinoids have been shown to upregulate GJIC and Cx43 expression levels in a variety of cell types through both transcriptional and translational mechanisms of action (Stahl and Sies, 1998; Carystinos et al, 2001). However, only a few studies describe the effects of RA on the female reproductive system (Day et al, 1998). Our previous work suggested that RA‐mediated dephosphorylation of Cx43 may play a role in the ability of this retinoid to increase GJIC in human ESCs (Tanmahasamut and Sidell, 2005).…”