Uptake of dehydroepiandrosterone-3-sulfate by isolated trophoblasts from human term placenta, JEG-3, BeWo, Jar, BHK cells, and BHK cells transfected with human sterylsulfatase-cDNA
The human placenta lacks the enzyme 17α-hydroxylase/17-20-lyase, and is thus unable to convert cholesterol into estrogens. Therefore estrogen synthesis of trophoblast cells depends on the supply of precursors such as dehydroepiandrosterone-3-sulfate (DHEA-S) and 16α-hydroxy-dehydroepiandrosterone-3-...
Saved in:
Published in | The Journal of steroid biochemistry and molecular biology Vol. 71; no. 5; pp. 203 - 211 |
---|---|
Main Authors | , |
Format | Journal Article |
Language | English |
Published |
Oxford
Elsevier Ltd
31.12.1999
Elsevier Science |
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | The human placenta lacks the enzyme 17α-hydroxylase/17-20-lyase, and is thus unable to convert cholesterol into estrogens. Therefore estrogen synthesis of trophoblast cells depends on the supply of precursors such as dehydroepiandrosterone-3-sulfate (DHEA-S) and 16α-hydroxy-dehydroepiandrosterone-3-sulfate by maternal and fetal blood. To investigate the cellular internalisation of these anionic hydrophilic precursors, the uptake of [
3H]-/[
35S]-DHEA-S and [
3H]-taurocholate by isolated cytotrophoblasts, cells of choriocarcinoma cell lines (JEG-3, BeWo, Jar), BHK and BHK cells transfected with human sterylsulfatase-cDNA (BHK-STS cells) was studied. Furthermore, the activity of sterylsulfatase of these cells in suspension and in corresponding cell homogenate was measured.
During the first 5 min of incubation with [
3H]-DHEA-S or [
35S]-DHEA-S, radioactivity of cytotrophoblasts increased significantly, while radioactivity of JEG-3, Jar, BHK and BHK-STS cells did not increase. Radioactivity of BeWo cells increased slightly. For all cell types, there was no significant difference for uptake of either substrate. During incubation with [
3H]-taurocholate, radioactivity of cytotrophoblasts did not increase. Sterylsulfatase activity of cytotrophoblast homogenate was significantly lower than that of cytotrophoblast suspension. Sterylsulfatase activity of BHK-STS, JEG-3 or BeWo cell homogenate was significantly higher than that of the corresponding cell suspension. In BHK and Jar cells sterylsulfatase activity was not detectable.
Cytotrophoblasts take up DHEA-S without prior hydrolysis. BHK, BHK-STS, JEG-3, and Jar cells do not take up and BeWo cells slowly take up DHEA-S. In cytotrophoblasts extracellular DHEA-S rapidly gains access to intracellular sterylsulfatase, while in choriocarcinoma and BHK-STS cells access of DHEA-S to sterylsulfatase is limited. Our results indicate, that uptake by cytotrophoblasts is mediated by a carrier which is not expressed in choriocarcinoma or BHK cells and which is different from the known taurocholate-transporting organic anion transporting polypetides. |
---|---|
Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0960-0760 1879-1220 |
DOI: | 10.1016/S0960-0760(99)00138-7 |