Expression of calcium channels along the differentiation of cultured trophoblast cells from human term placenta.
Placental transfer of maternal calcium (Ca2+) is carried out in vivo by the syncytiotrophoblast layer. Although this process is crucial for fetal development, it remains poorly understood. Cytotrophoblasts isolated from human term placenta undergo spontaneous syncytiotrophoblast-like morphological and biochemical differentiation in vitro and are thought to reflect in vivo syncytiotrophoblast. In the present study, we characterized the Ca2+ uptake potential and the expression of several Ca2+ channels by human trophoblasts during differentiation in vitro for up to 6 days. Secretion of hCG (specific differentiation marker) and uptake of Ca2+ by trophoblasts increased gradually as a function of days in culture. Both hCG secretion and Ca2+ uptake were maximal on Day 4 and declined on Days 5-6. Expression of the Ca2+ transporter proteins CaT1 and CaT2 was revealed by reverse transcription-polymerase chain reaction in cytotrophoblasts freshly isolated from human term placenta. In addition, messengers for two L-type Ca2+ channel isoforms (alpha(1C) and alpha(1D)) were also detected. Levels of CaT1, CaT2, and L-type Ca2+ channel mRNA increased gradually during culture, reaching a maximum between Days 2 and 3. In contrast to CaT1 and CaT2 expression that declined thereafter to levels observed on Day 1, L-type channel expression decreased by 50% but remained above the expression level of Day 1. Our results indicate that the pattern of CaT1 and CaT2 expression correlates with the Ca2+ uptake potential along the differentiation of cultured human trophoblasts isolated from term placenta. This correlation provides circumstantial evidence for a role of this family of channels in basal Ca2+ uptake by the syncytiotrophoblast.
Moreau
Robert
R
Laboratoire de Physiologie materno-foetale, Département des Sciences Biologiques, Université du Québec à Montréal, Montréal, Québec, Canada H3C 3P8.
Hamel
Annie
A
Daoud
Georges
G
Simoneau
Lucie
L
Lafond
Julie
J
D026923:Amino Acid Transport Systems, Basic; D002118:Calcium / Q000378:metabolism / Q000493:pharmacokinetics; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology*; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D010920:Placenta / Q000166:cytology*; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D012333:RNA, Messenger / Q000378:metabolism; D050916:TRPV Cation Channels; D014327:Trophoblasts / Q000166:cytology / Q000378:metabolism*
D026923:Amino Acid Transport Systems, Basic; D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D006063:Chorionic Gonadotropin; D012333:RNA, Messenger; C414177:SLC7A2 protein, human; D050916:TRPV Cation Channels; C120776:TRPV6 channel; D002118:Calcium