82 EXPRESSION OF CELL MEMBRANE Mg²⁺ INORGANIC PHOSPHATE CHANNELS IN THE HUMAN PLACENTA DERIVED FROM PREGNANT WOMEN AND HUMAN PLACENTAL CELL LINES (BeWo, JEG3, hPC)

Abstract

Preeclampsia is a pregnancy-specific disease characterised by de novo development of concurrent hypertension and oxidative stress in the placenta. The human placenta is a highly vascularized organ whose major function is to allow maternal–fetal exchange of solutes such as Ca²⁺ and oxygen. The transient receptor potential cation channel subfamily is known to contain channels activated by such various stimuli as intracellular Ca²⁺ membrane potential, cold and pH. However, signalling mechanisms mediating hormonal regulation of Mg²⁺ inorganic phosphate channels during the placenta duration of pregnancy are incompletely understood. We examined the expression of cell membrane Mg²⁺ inorganic channels in 3 sections (fetal-, central-, maternal-) of preeclamptic placenta (PEP) and from placental cell lines, BeWo, JEG3 and hPC (isolated during the first trimester) by real-time PCR and Western blot analysis. Placental tissues (∼3 cm) from women (n = 75) between the ages of 28 to 45 years undergoing normal or Caesarean delivery were dissected into 1-cm sections. Data were analysed by one-way ANOVA, followed by Tukey's multiple comparison test. P < 0.05 was considered to be statistically significant. During preterm labour, human placental expression of Mg²⁺ inorganic channel mRNA and protein fluctuated in the 3 sections of PEP compared with normal placenta. In hPC, the expression of Mg²⁺ inorganic channel (TRPM6/7, MagT1, NIPA2, SLC41A1 to 3 and SLC34A1 to 3) mRNA and protein were decreased in placental cell lines by hypoxic stress (2% O₂/93% N₂/5% CO₂) compared with normoxia (20% O₂/75% N₂/5% CO₂). The levels of Mg²⁺ inorganic channel mRNA and protein were distinctly expressed between BeWo and JEG3 cells. These results indicate that placental Mg²⁺ inorganic channels play potential roles in differential sections of placenta between normal and PEP, suggesting that induced Mg²⁺ inorganic channels of PEP may be involved in preeclamptic stress in human placenta and placental cell lines, which are a determinant factor affecting calcium transfer.