Connexin expression and gap junctional intercellular communication in human first trimester trophoblast

Abstract

Connexin (Cx) expression and gap junctional intercellular communication (GJIC) are involved in development and differentiation processes, and recently mutation of connexin genes has been implicated in pathologies. In the human placenta, two distinct differentiation pathways of cytotrophoblastic cells coexist and lead to a fusion phenotype (villous trophoblast) and a proliferative/invasive phenotype (extravillous trophoblast). Here we characterized in situ and in vitro the expression of Cx transcripts and proteins in the villous and extravillous trophoblast of first trimester placenta. In addition, the GJIC functionality was investigated using the gap-fluorescence recovery after photobleaching (gap-FRAP) method. We demonstrated in the villous trophoblast the presence of Cx43 mRNA and of Cx43 protein localized between cytotrophoblastic cells and between cytotrophoblastic cells and syncytiotrophoblast. In vitro, a transient functional gap junctional intertrophoblastic communication was demonstrated during the trophoblast fusion leading to the multinucleated syncytiotrophoblast. During the proliferative process of the extravillous trophoblast, Cx40 is expressed in the proximal part of the cell columns. When cytotrophoblastic cells were cultured on Matrigel for 2 days, alpha5beta1 integrin expression was observed concomitant with the presence of Cx40 mRNA and of Cx40 protein between the cells. No evidence for a GJIC was detected in this induced extravillous phenotype. In addition, Cx32 was detected between some aggregated cells after 72 h of culture. Our data show that the presence of Cx43 allows an inter-trophoblastic GJIC and is associated with the fusion process leading to the villous syncytiotrophoblast and that the presence of Cx40 does not allow GJIC and is associated with the extravillous phenotype.

Endothelin‐1 inhibits human osteoblastic cell differentiation: Influence of connexin‐43 expression level

“…Coupled cells were characterized by an exponential time course of fluorescence recovery from neighboring cells into a photobleached test cell (Fig. 1F) as previously described [Cronier et al, 2002]. A functional communication was measured between hFOB cells in both conditions and the percentages of coupled cells were 44.5% (n ¼ 77) and 58.1% (n ¼ 93) at 33.58C and 398C, respectively (Fig.…”

A PKA-ezrin-connexin 43 signaling complex controls gap junction communication and thereby trophoblast cell fusion

“…Human cytotrophoblasts that are able to fuse and differentiate to syncytiotrophoblasts express Cx43 as their only gap junction protein (Cronier et al, 2002;Cronier et al, 2003;Dunk et al, 2012;Frendo et al, 2003a). Cx43 phosphorylation by PKA, MAP kinase and PKC is speculated to differentially regulate gap junction assembly, communication and recycling (Solan and Lampe, 2009).…”

Human Placental Development Is Impaired by Abnormal Human Chorionic Gonadotropin Signaling in Trisomy 21 Pregnancies

“…After sequential trypsin/DNase I digestion followed by Percoll gradient centrifugation, the cells were further purified by negative selection to obtain a trophoblast preparation not contaminated by other cells, using monoclonal antihuman leukocytic antigen A, B, and C antibodies (W6-32HL; Sera Lab, Crawley Down, UK) according to a published method (36,37). This antibody reacts with most cell types (e.g.…”