Involvement of connexin 43 in human trophoblast cell fusion and differentiation

• DOI: 10.1242/jcs.00648
• Publication Date: 2003-07-08T00:22:33Z
• Authors: Jean-Louis Frendo; Laurent Cronier; Gwladys Bertin; Jean Guibourdenche; Michel Vidaud; Danièle Evain-Brion; André Malassiné
• Keywords: 0301 basic medicine; MESH: Cytoskeletal Proteins; MESH: Gap Jun; Placenta; Cell Communication; Chorionic Gonadotropin; Cell Fusion; 03 medical and health sciences; MESH: Desmoplakins; MESH: Chorionic Gonadotropin; MESH: Cell Communication; Humans; Chorionic Gonadotropin, beta Subunit, Human; Cells, Cultured; Endogenous Retroviruses; Gap Junctions; [SDV.BDLR]Life Sciences [q-bio]/Reproductive Biology; Oligonucleotides, Antisense; Immunohistochemistry; MESH: Connexin 43; Trophoblasts; Cytoskeletal Proteins; Desmoplakins; MESH: Cell Fusion; Connexin 43; MESH: Chorionic Gonadotropin, beta Subunit, Human; Female; MESH: Female; MESH: Fluorescence Recovery After Photobleaching; MESH: Endogenous Retroviruses; MESH: Cells, Cultured; Fluorescence Recovery After Photobleaching

The syncytiotrophoblast is the principal component of the human placenta involved in feto-maternal exchanges and hormone secretion. The syncytiotrophoblast arises from the fusion of villous cytotrophoblasts. We recently showed that functional gap junctional intercellular communication(GJIC) is an important prerequisite for syncytiotrophoblast formation and that connexin 43 (Cx43) is present in cytotrophoblasts and in the syncytiotrophoblast. To determine whether Cx43 is directly involved in trophoblast fusion, we used an antisense strategy in primary cultures of human villous cytotrophoblasts that spontaneously differentiate into the syncytiotrophoblast by cell fusion. We assessed the morphological and functional differentiation of trophoblasts by desmoplakin immunostaining, by quantifying hCG (human chorionic gonadotropin) production and by measuring the expression of specific trophoblast genes (hCG and HERV-W). Furthermore, we used the gap-FRAP (fluorescence recovery after photobleaching) method to investigate functional GJIC. Cytotrophoblasts treated with Cx43 antisense aggregated and fused poorly. Furthermore, less HERV-W env mRNA, hCGβ mRNA and hCG secretion were detected in Cx43 antisense-treated cytotrophoblasts than in cells treated with scrambled antisense. Treatment with Cx43 antisense dramatically reduced the percentage of coupled trophoblast cells. Taken together, these results suggest that Cx43 is directly involved in human trophoblast cell-cell communication, fusion and differentiation.