connexin; extravillous trophoblast; gap junction; placenta; villous trophoblast
Abstract :
[en] 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(R) 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.
Al-Lamki, R.S.A.I., Skepper, J.N. and Burton, G.J. (1999) Are human placental bed giant cells merely aggregates of small mononuclear trophoblast cells? An ultrastructural and immunocytochemical study. Hum. Reprod., 14, 496-504.
Aplin, J., Haigh, T., Lacey, H. et al. (2000) Tissue interaction in the control of trophoblast invasion. J. Reprod. Fertil., 55, 57-64.
Benirschke, K. and Kaufmann, P. (eds) (2000) Pathology of the Human Placenta, 4th edn. Springer Verlag, New York.
Boyd, J.D. and Hamilton, W.J. (1970) The Human Placenta. W.Heffer, Cambridge.
Bruzzone, R., White, T.W. and Paul, D.L. (1996) Connections with connexins: the molecular basis of a direct intercellular signaling. Eur. J. Biochem., 238, 1-27.
Burrows, T.D., King, A. and Loke, Y.W. (1993) Expression of integrins by human trophoblast and differential adhesion to laminin or fibronectin. Hum. Reprod., 8, 475-488.
Cottrell, G.T. and Burt, J.M. (2001) Heterotypic gap junction channel formation between heteromeric and homomeric Cx40 and Cx43 connexons. Am. J. Physiol., 281, C1559-C1567.
Cronier, L., Alsat, E., Hervé, J.C. et al. (1994a) Inhibition of gap junctional communication, trophoblast differentiation and hCS expression by heptanol in human trophoblast in culture. Placenta, 15, A10.
Cronier, L., Bastide, B., Hervé, J.C. et al. (1994b) Gap junctional communication during human trophoblast differentiation: influence of human chorionic gonadotropin. Endocrinology, 135, 402-408.
Cronier, L., Hervé, J.C., Délèze, J. and Malassiné, A. (1997) Regulation of gap junctional communication during human trophoblast differentiation. Microsc. Res. Tech., 38, 21-28.
Cronier, L., Bastide, B., Defamie, N. et al. (2001) Involvement of gap junctional communication and connexin expression in trophoblast differentiation of the human placenta. Histol. Histopathol., 16, 285-295.
Dale, B., Santella, L. and Tosti, E. (1991) Gap-junctional permeability in early and cleavage-arrested ascidian embryos. Development, 112, 153-160.
Damsky, C.H., Librach, C., Lim, K.H. et al. (1994) Integrin switching regulates normal trophoblast invasion. Development, 120, 3657-3666.
Dodeur, M., Malassiné, A., Bellet, D. et al. (1990) Characterization and differentiation of human first trimester placenta trophoblastic cells in culture. Rep. Nutr. Dev., 30, 183-192.
Enders, A.C., Blankenship, T.N., Fazleabas, A.T. et al. (2001) Structure of anchoring villi and the trophoblastic shell in the human, baboon and macaque placenta. Placenta, 22, 284-303.
Furger, C., Cronier, L., Poirot, C. et al. (1996) Human granulosa cells in culture exhibit functional cyclic AMP-regulated gap junctions. Mol. Hum. Reprod., 2, 541-548.
Gabriel, H.D., Jung, D., Bützler, C. et al. (1998) Transplacental uptake of glucose is decreased in embryonic lethal connexin26 deficient mice. J. Cell Biol., 140, 1453-1461.
Gros, D., Jarry-Guichard, T., Ten Velde, I. et al. (1994) Restricted distribution of connexin40, a gap junctional protein, in mammalian heart. Circ. Res., 74, 839-851.
Hellmann, P., Winterhager, E. and Spray, D.C. (1996) Properties of connexin40 gap junction channels endogenously expressed and exogenously overexpressed in human choriocarcinoma cell lines. Eur. J. Physiol., 432, 501-509.
Kaufmann, P. and Castellucci, M. (1997) Extravillous trophoblast in the human placenta. A review. Trophoblast Res., 10, 21-65.
Kliman, H.J., Nestler, J.E., Sermasi, E. et al. (1986) Purification, characterization, and in vitro differentiation of cytotrophoblasts from human term placentae. Endocrinology, 118, 1567-1582.
Krutovskikh, V. and Yamasaki, H. (1997) The role of gap junctional intercellular communication (GJIC) disorders in experimental and human carcinogenesis. Histol. Histopathol., 12, 761-768.
Kumar, N.M. and Gilula, N.B. (1996) The gap junction communication channel. Cell, 84, 381-388.
Lo, C.W. (1999) Genes, gene knockouts, and mutations in the analysis of gap junctions. Dev. Genet., 24, 1-4.
Malassiné, A. and Leiser, R. (1984) Morphogenesis and fine structure of the near-term placenta of talpa europaea: I. Endotheliochorial labyrinth. Placenta, 5, 145-158.
Plum, A., Winterhager, E., Pesch, J. et al. (2001) Connexin31-deficiency in mice causes transient placental dysmorphogenesis but does not impair hearing and skin differentiation. Dev. Biol., 231, 334-347.
Reuss, B., Hellmann, P., Dahl, E. et al. (1996) Connexins and E cadherin are differentially expressed during trophoblast invasion and placental differentiation. Dev. Dynam., 205, 172-182.
Rossant, J. and Cross, J.C. (2001) Placental development: lessons from mouse mutants. Nature Rev. Genet., 2, 538-548.
Schmon, B., Hartmann, M., Jones, C.J. and Desoye, G. (1991) Insulin and glucose do not affect the glycogen content in isolated and cultured trophoblast cells of human term placenta. J. Clin. Endocrinol., 73, 888-893.
Sibony, M., Commo, F., Callard, P. and Gasc, J.M. (1995) Enhancement of mRNA in situ hybridization signal by microwave heating. Lab. Invest., 73, 586-591.
Tabb, T., Thilander, G., Grover, A. et al. (1992) An immunocytologic study of the increase in myometrial gap junctions (and connexin43) in rats and humans during pregnancy. Am. J. Obstet. Gynecol., 167, 559-587.
Takata, K. and Hirano, H. (1997) Mechanism of glucose transport across the human and rat placental barrier: a review. Microsc. Res. Tech., 38, 145-152.
Tanaka, T., Yamasaki, H. and Mesnil, M. (2001) Induction of a bystander effect in HeLa cells by using a bigenic vector carrying viral thymidine kinase and connexin32 genes. Mol. Carcinogen., 30, 176-180.
Tarrade, A., Lai Kuen, R., Malassiné, A. et al. (2001) Characterization of human villous and extravillous trophoblast isolated from first trimester placenta. Lab. Invest., 81, 1199-1211.
Valiunas, V., Gemel, J., Brink, P.R. and Beyer, E.C. (2001) Gap junction channels formed by coexpressed connexin40 and connexin43. Am. J. Physiol., 281, H1675-H1689.
Vicovac, L. and Aplin, J.D. (1996) Epithelial-mesenchymal transition during trophoblast differentiation. Acta Anat., 156, 202-216.
Wade, M.H., Trosko, J.E. and Schindler, M. (1986) A fluorescence photobleaching assay of gap junction-mediated communication between human cells. Science, 232, 525-528.
Warner, A. (1988) The gap junction. J. Cell Sci., 89, 1-7.
Willecke, K., Hennemann, H., Dahl, E. et al. (1991) The diversity of connexin genes encoding gap junctional proteins. Eur. J. Cell Biol., 6, 459-470.
Winterhager, E., von Ostau, C., Gerke, M. et al. (1999) Connexin expression patterns in human trophoblast cells during placental development. Placenta, 20, 627-638.
Winterhager, E., Kaufmann, P. and Gruemmer, R. (2000) Cell-cell -communication during placental development and possible implications for trophoblast proliferation and differentiation. Placenta, 21, S61-S68.
