Regulation of beta-catenin mRNA and protein levels in human villous cytotrophoblasts undergoing aggregation and fusion in vitro: correlation with E-cadherin expression

Abstract

The cellular mechanisms underlying the formation and organization of the human placenta remain poorly understood. Recent studies have demonstrated that E-cadherin, in association with the cytoplasmic protein known as beta-catenin, plays an integral role in the differentiation of the trophectoderm in the murine and bovine embryo. Although E-cadherin expression is regulated during the aggregation and fusion of human villous cytotrophoblasts, the expression of beta-catenin during the terminal differentiation of these primary cell cultures has not been determined. In this study, beta-catenin mRNA concentrations and protein expression were examined in primary cultures of human villous cytotrophoblasts using northern and western blot analysis. beta-catenin mRNA concentrations and protein expression were high in freshly isolated mononucleate cytotrophoblasts but decreased as these cells underwent aggregation and fusion to form syncytium. A similar pattern of expression was observed for the E-cadherin mRNA transcript and protein species present in these cell cultures. Immunoprecipitation studies demonstrated that the beta-catenin and E-cadherin protein species present in the mononucleate cytotrophoblasts were capable of forming intracellular complexes. In contrast, beta-catenin and E-cadherin mRNA and protein expression in JEG-3 choriocarcinoma cells remained constant over time in culture. beta-catenin and E-cadherin expression was subsequently immunolocalized to the aggregates of mononucleate cells present in both of these trophoblastic cell cultures and the villous cytotrophoblasts of the human first trimester and term placenta. Taken together, these observations indicate that the E-cadherin-beta-catenin complex plays a central role in the terminal differentiation of human trophoblasts in vitro and in vivo.

Targeting and crossing of the human maternofetal barrier byListeria monocytogenes: Role of internalin interaction with trophoblast E-cadherin

“…2A). This finding was consistent with previously reported analyses (16)(17)(18), but was inconsistent with the hypothesis that blood-borne L. monocytogenes would interact with E-cadherin at the apical surface of syncytiotrophoblasts. However, our previous work on intestinal tissue had established that immunofluorescent labeling of E-cadherin with HECD-1 of fresh cryosections yielded a specific and far more intense signal than with immunoenzymatic labeling of formalin fixed, paraffinembedded tissue (10).…”

E-cadherin in the assessment of aberrant placental cytotrophoblast turnover in pregnancies complicated by pre-eclampsia

“…The expression of E-cadherin by villus cytotrophoblasts has previously been documented (Coutifaris et al 1991;MacCalman et al 1996;Getsios et al 2000). In BeWo cells and primary cultured cytotrophoblasts, Ecadherin, which is constitutively expressed at points of cell-cell contact, declines upon the fusion and differentiation that accompanies syncytiotrophoblast formation (Coutifaris et al 1991).…”

“…It promotes cell-cell interactions between epithelial cells; it has a role in maintaining differentiation; and is down-regulated during cell motility and invasion (Wheelock and Johnson 2003). Presently, the role of E-cadherin in trophoblast turnover is undefined, although it is down-regulated following the terminal differentiation of trophoblast cells in vitro (Getsios et al 2000).…”

Placental Expression of Secreted Frizzled Related Protein-4 in the Rat and the Impact of Glucocorticoid-Induced Fetal and Placental Growth Restriction

“…Collectively, these data indicate that the subcellular localization of SFRP4 may determine its The effects of WNT pathway inhibition by frizzled related proteins, including SFRP4, are likely to be mediated via effects on CTNNB1 localization [21,22]. Thus, the canonical WNT pathway promotes proliferation via the nuclear accumulation of CTNNB1 and subsequent activation of the TCF/LEF family of transcription factors [13,14] and has been implicated specifically in trophoblast differentiation [17,19] and survival [18]. The present study shows that increased expression of SFRP4 in basal zone trophoblasts is accompanied by reduced CTNNB1 nuclear localization, consistent with inhibition of the WNT pathway by SFRP4.…”

“…Moreover, Fzd5 knockout mice display defects in placental vascularization, implicating a role for WNT5A and WNT10B, the physiological ligands of FZD5, in placental development [10]. A role for CTNNB1, the key mediator of WNT signaling, has also been implicated in trophoblast adhesion [17], survival [18], and differentiation [19].…”