Inhibition of amino acid transport system A by interleukin-1β in trophoblasts

Boonrit Thongsong, Radhika K. Subramanian, Vadivel Ganapathy, Puttur D Prasad

Research output: Contribution to journalArticle

31 Scopus citations

Abstract

OBJECTIVE: The current study sought to investigate the influence of interleukin-1β (IL-1β) on the function of the amino acid transport system A in trophoblasts. METHODS: BeWo choriocarcinoma cells were exposed to recombinant human IL-1β in serum-free medium. Cells incubated with serum-free medium in the absence of IL-1β were used as control. System A activity was determined in control and treated cells by measuring the uptake of α-(methylamino)isobutyric acid. The results obtained were confirmed by measuring system A activity in placental brush border membrane vesicles isolated from pregnant rats injected with IL-1β. RESULTS: Treatment of BeWo cells with IL-1β resulted in a time- and dose- dependent inhibition of system A. Treatment with IL-1β also inhibited the uptake of arginine, and glutamate but had no significant effect on the uptake of leucine, tryptophan, and ascorbate. The inhibition of system A activity by IL-1β was abolished in the presence of IL-1β receptor antagonist. The inhibitory effect was associated with a decrease in the maximal velocity of the transport system with no effect on the substrate affinity. Steady-state levels of both SNAT1 and SNAT2 mRNA were reduced by IL-1β treatment as evidenced by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. In rat placental brush border membrane vesicles isolated from IL-1β-treated pregnant rats, system A activity was found to be decreased by approximately 40% compared to activity in control membrane vesicles. CONCLUSIONS: IL-1β decreases SNAT1 and SNAT2 mRNA levels in trophoblasts, which is associated with a decrease in system A-mediated transport activity at the functional level. These findings may have important consequences under both physiologic conditions and pathologic conditions during pregnancy that are associated with elevated levels of IL-1β.

Original languageEnglish (US)
Pages (from-to)495-503
Number of pages9
JournalJournal of the Society for Gynecologic Investigation
Volume12
Issue number7
DOIs
StatePublished - Oct 1 2005

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Keywords

  • Amino acid transporter
  • Interleukins
  • Pregnancy
  • Regulation
  • Trophoblast

ASJC Scopus subject areas

  • Obstetrics and Gynecology

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