Connexins and E‐cadherin are differentially expressed during trophoblast invasion and placenta differentiation in the rat

Abstract

We have characterized the spatial and temporal expression pattern of six different connexin genes and E-cadherin during trophectoderm development in the rat. During the initial phase of trophoblast invasion at 6 days postcoitum (dpc), the trophoblast expressed E-cadherin but no connexin expression could be observed. With progressing invasion of the polar trophoblast into the maternal decidua, from 7 dpc onwards E-cadherin expression in the ectoplacental cone cells was lost and was now restricted to the extraembryonic ectoderm. In the ectoplacental cone and extraembryonic ectoderm instead connexin31 mRNA and protein could be found. This pattern was maintained up to day 10 postcoitum. The start of labyrinthine trophoblast differentiation from day 11 postcoitum onwards was characterized by persisting expression of E-cadherin in the extraembryonic ectoderm and its derivative, the chorionic plate. In addition to E-cadherin, from 10 dpc onwards, connexin26 started to be expressed in the chorionic plate, and both molecules remained coexpressed in the labyrinthine trophoblast of the mature placenta. During this differentiation process connexin31 remained expressed mainly in the proliferating spongiotrophoblast. From day 14 postcoitum onwards, the expression of connexin31 in the spongiotrophoblastic cells decreased, and in parallel they started to express connexin43. The trophoblastic giant cells, first characterized by connexin31, lost all of the investigated connexins during midgestation on day 12 postcoitum but started to express connexin43 from day 18 postcoitum onwards. Our studies suggest that loss of E-cadherin and induction of connexin31 expression is correlated with the proliferative and invasive stages of the ectoplacental cone, whereas appearance of connexin26, E-cadherin and connexin43 reflects the switch to the differentiated phenotypes of the mature placenta.

Trophoblast differentiation in vitro: establishment and characterisation of a serum-free culture model for murine secondary trophoblast giant cells

“…Our study demonstrated that E-cadherin protein expression was extremely low or undetectable in secondary trophoblast outgrowth in vitro. Similar results were shown in other mammalian embryos where downregulation of E-cadherin was coincident with the differentiation of TGCs in the rat (Reuss et al 1996), and with the differentiation of non-invasive cytotrophoblast into invasive trophoblast in the human (Coutifaris et al 1991, Floridon et al 2000.…”

“…Moreover, trophectoderm and TGCs express a 7 integrins (laminin receptors) in the early postimplantation mouse embryo which may facilitate their invasion into the uterine stroma (Sutherland et al 1993, Klaffky et al 2001. On the other hand, E-cadherin, a member of the cadherin family of adhesion molecules, is expressed by embryonic ectoderm, trophectoderm and labyrinthine trophoblast cells, but is absent on TGCs in the rat (Reuss et al 1996).…”

Origin and characteristics of glycogen cells in the developing murine placenta

“…its derivatives Reuss et al, 1996). This expression persists and Cx31 is found in the Jz followed by a coexpression of Cx43 at early midgestation (Kibschull et al, 2005).…”

Responsiveness of endometrial genes Connexin26, Connexin43, C3 and clusterin to primary estrogen, selective estrogen receptor modulators, phyto- and xenoestrogens

“…Exposure to Kodak XAR-5 films took place at 80 C with intensifying screens. After exposure, each blot was re-hybridized with a rat actin-specific cDNA probe (Reuss et al 1996) using the same conditions of hybridization.…”