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Journal of Cell Science, Vol 98, Issue 3 333-342, Copyright © 1991 by Company of Biologists
JOURNAL ARTICLES |
RS Tuan, CJ Moore, JW Brittingham, JJ Kirwin, RE Akins and M Wong
Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, PA 19107.
During human fetal development, placental syncytiotrophoblasts actively transport calcium from the maternal to the fetal circulation. Two functional components, a cytosolic Ca2(+)-binding protein (CaBP) and a Ca2(+)-ATPase have been identified in the syncytiotrophoblasts of the chorionic villi. We report here the calcium uptake properties of a human choriocarcinoma cell line, JEG-3, which was used as an in vitro model cell system for the syncytiotrophoblasts. In culture, JEG-3 proliferated as large syncytial aggregates expressing typical syncytiotrophoblast markers. 45Ca uptake by JEG-3 was a substrate- and temperature-dependent, membrane-mediated active process that exhibited linear kinetics for up to 7 min. Both the CaBP and the Ca2(+)-ATPase were expressed by JEG-3, on the basis of biochemical, histochemical, immunochemical and or mRNA assays. Immunohistochemistry and in situ hybridization revealed that JEG-3 cells were heterogeneous with respect to the expression of the CaBP. The Ca2(+)-ATPase activity of JEG-3 was similar to the placental enzyme in terms of sensitivity to specific inhibitors, and was detected histochemically along the cell membrane. Fura-2 Ca2+ imaging revealed that calcium uptake by JEG-3 was not accompanied by a concomitant increase in cytosolic [Ca2+], suggesting a specific Ca2+ sequestration mechanism. The involvement of calciotropic hormonal regulation was evaluated by studying the response of JEG-3 to 1,25-dihydroxy vitamin D3. Calcium uptake was significantly stimulated in a dose-dependent manner by a 24-h treatment of the cells with 1,25-dihydroxy vitamin D3 (optimal dose approximately 0.5 nM); the CaBP level doubled whereas steady-state CaBP mRNA did not, suggesting that CaBP expression was regulated by 1,25-dihydroxy vitamin D3. These observations strongly suggest that the JEG-3 human choriocarcinoma cells should serve as a convenient in vitro model system for studying the cellular mechanism and regulation of transplacental calcium transport.
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  K. N. Evans, J. N. Bulmer, M. D. Kilby, and M. Hewison Vitamin D and Placental-Decidual Function Reproductive Sciences, July 1, 2004; 11(5): 263 - 271. [Abstract] [PDF]
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 T. Hahn, S. Barth, U. Weiss, W. Mosgoeller, and G. Desoye Sustained hyperglycemia in vitro down-regulates the GLUT1 glucose transport system of cultured human term placental trophoblast: a mechanism to protect fetal development? FASEB J, September 1, 1998; 12(12): 1221 - 1231. [Abstract] [Full Text]
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 R. Akins and R. Tuan Transepithelial calcium transport in the chick chorioallantoic membrane. I. Isolation and characterization of chorionic ectoderm cells J. Cell Sci., January 6, 1993; 105(2): 369 - 379. [Abstract] [PDF]
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