Regulation of taurine transport at the blood-placental barrier by calcium ion, PKC activator and oxidative stress conditions

Na-Young Lee,Young-Sook Kang

doi:10.1186/1423-0127-17-s1-s37

Abstract

BackgroundIn the present study, we investigated the changes of uptake and efflux transport of taurine under various stress conditions using rat conditionally immortalized syncytiotrophoblast cell line (TR-TBT cells), as in vitro blood-placental barrier (BPB) model.MethodsThe transport of taurine in TR-TBT cells were characterized by cellular uptake study using radiolabeled taurine. The efflux of taurine was measured from the amount of radiolabeled taurine remaining in the cells after the uptake of radiolabeled taurine for 60 min.ResultsTaurine uptake was significantly decreased by phosphorylation of protein kinase C (PKC) activator in TR-TBT cells. Also, calcium ion (Ca2+) was involved in taurine transport in TR-TBT cells. Taurine uptake was inhibited and efflux was enhanced under calcium free conditions in the cells. In addition, oxidative stress induced the change of taurine transport in TR-TBT cells, but the changes were different depending on the types of oxidative stress inducing agents. Tumor necrosis factor-α (TNF-α), lipopolysaccharide (LPS) and diethyl maleate (DEM) significantly increased taurine uptake, but H2O2 and nitric oxide (NO) donor decreased taurine uptake in the cells. Taurine efflux was down-regulated by TNF-α in TR-TBT cells.ConclusionTaurine transport in TR-TBT cells were regulated diversely at extracellular Ca2+ level, PKC activator and oxidative stress conditions. It suggested that variable stresses affected the taurine supplies from maternal blood to fetus and taurine level of fetus.

Highlights

Taurine, one of the essential nutrients, exists in high concentration in most tissues, where it shows various physiological functions such as including conjugation with bile acids, anti-oxidation, detoxification, osmoregulation, membrane stabilization and modulation of intracellular calcium level [1,2,3,4]
Effect of protein kinase C (PKC) on the taurine uptake in TR-TBT cells Taurine transport was regulated by phosphorylation of PKC in TR-TBT cells
Effect of Ca2+ and calcium channel blockers on the taurine transport in TR-TBT cells We investigated the effect of Ca2+ on taurine transport in TR-TBT cells by removal of Ca2+ from extracellular fluid (ECF) buffer or addition of various calcium channel blockers in ECF buffer

Summary

Introduction

One of the essential nutrients, exists in high concentration in most tissues, where it shows various physiological functions such as including conjugation with bile acids, anti-oxidation, detoxification, osmoregulation, membrane stabilization and modulation of intracellular calcium level [1,2,3,4]. Taurine plays an important role in fetal development because taurine deficiency during pregnancy is associated with growth retardation, retinal degeneration and dysfunction of the central nervous system (CNS) [5,6]. It showed that the level of taurine in the fetus at intrauterine growth restriction (IUGR) was low [10], NO level was high in IUGR pregnancies [11] It suggests a mutual relation between oxidative stress and taurine transport. We investigated the changes of uptake and efflux transport of taurine under various stress conditions using rat conditionally immortalized syncytiotrophoblast cell line (TR-TBT cells), as in vitro blood-placental barrier (BPB) model

Methods

Results

Discussion

Conclusion