Activity and expression of Na(+)-K(+)-ATPase in human placental cytotrophoblast cells in culture.
1. To determine whether there is a change during differentiation, the activity and expression of Na(+)-K(+)-ATPase were studied in mononucleate cytotrophoblast cells (18 h culture) and syncytiotrophoblast-like cells (66 h culture). A choriocarcinoma-derived cell line (JAr) which, unlike the cytotrophoblast cells, divides in culture, was also studied for comparison. 2. Na(+)-K(+)-ATPase activity was assessed by measurement of ouabain-sensitive 86Rb+ uptake. Na(+)-K(+)-ATPase expression was determined by (i) measurement of [3H]ouabain binding and (ii) Northern hybridization to measure expression of alpha-1 and beta 1-subunit mRNA. 3. There was no significant difference in either activity or expression of Na(+)-K(+)-ATPase during differentiation of cytotrophoblast cells. However, expression of alpha 1- and beta 1-subunit mRNA was significantly lower in 66 vs. 18 h cultured cytotrophoblast cells. 4. Both Na(+)-K(+)-ATPase activity and [3H]ouabain binding was significantly greater in JAr cells than either cytotrophoblast cell groups, although expression of alpha 1- and beta 1-subunit mRNA was the same as cytotrophoblast cells cultured for 18 h. 5. It is concluded that N(+)-K(+)-ATPase activity and protein expression does not change during differentiation of cytotrophoblast cells but that there are changes in expression at the transcriptional or post-transcriptional level.
Clarson
L H
LH
Department of Child Health and School of Biological Sciences, University of Manchester, St Mary's Hospital, UK. lclarson@fs1.mci.man.ac.uk
Glazier
J D
JD
Greenwood
S L
SL
Jones
C J
CJ
Sides
M K
MK
Sibley
C P
CP
D015152:Blotting, Northern; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000378:metabolism; D006801:Humans; D008854:Microscopy, Electron; D010042:Ouabain / Q000378:metabolism; D010920:Placenta / Q000166:cytology* / Q000201:enzymology; D012333:RNA, Messenger / Q000378:metabolism; D012413:Rubidium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics / Q000378:metabolism*; D014327:Trophoblasts / Q000201:enzymology*
D006063:Chorionic Gonadotropin; D012333:RNA, Messenger; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium