81 MEMBRANE AND CYTOSOLIC CALCIUM PROTEINS, TRPV6, PMCA1, NCKX3, NCX1 AND CaBP-28k, APPEAR TO BE DISTINCTLY REGULATED IN HUMAN CHORIOCARCINOMA AND PLACENTAL CELLS

Abstract

Preeclampsia is a pregnancy-specific disease characterised by de novo development of concurrent hypertension, proteinuria and oxidative stress in the placenta. In the placenta, intervillous blood flow increases after 10 weeks of gestation and results in exposure of trophoblast cells to oxygen. Hypoxia occurs during the development of placenta in the first trimester and is implicated in trophoblast differentiation. Ca²⁺ is a universal intracellular second messenger involved in many processes such as signal transduction, hormone secretion and programmed cell death. Human placental primary cell cultures were established from first-trimester human placentas (at 7 to 12 weeks of gestation). In this study, calcium-related proteins (CRPs; TRPV6, PMCA1, NCKX3 and CaBP-28k) were investigated at normoxia (5% CO₂ in 95% air) or hypoxia (2% O₂/93% N₂/5%CO₂) for 12 h in human placental cell line (BeWo) and human placental primary cell (hPC). We confirmed mRNA expression by real-time PCR and protein expression by Western blot analysis. The data were 2 or 3 individual experiments with triplicate samples and analysed by one-way ANOVA using Tukey's multiple comparison test. In hypoxia, the level of TRPV6 mRNA and protein was not changed, however, calcium transporters' (NCKX3, CaBP-28k) mRNA and protein expressions were significantly increased in hypoxic BeWo cell compared with control (normoxia). In addition, expression of PMCA1 mRNA and protein was decreased in hypoxic BeWo cells. In hPC, CRPs (TRPV6, PMCA1, NCKX3 and CaBP-28k) mRNA and protein expressions were significantly induced by hypoxic stress compared with control. These results, taken together, indicate that alterations of calcium transporters in hypoxic stress may be involved in calcium transport in the placenta and protection of the placental trophoblasts from the oxidative stress during the pregnancy.