Inhibition of amino acid transport system a by interleukin-1beta in trophoblasts.

  • Thongsong B
  • Subramanian R
  • Ganapathy V
 et al. 
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OBJECTIVE: The current study sought to investigate the influence of interleukin-1beta (IL-1beta) on the function of the amino acid transport system A in trophoblasts.

METHODS: BeWo choriocarcinoma cells were exposed to recombinant human IL-1beta in serum-free medium. Cells incubated with serum-free medium in the absence of IL-1beta were used as control. System A activity was determined in control and treated cells by measuring the uptake of alpha-(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-1beta.

RESULTS: Treatment of BeWo cells with IL-1beta resulted in a time- and dose- dependent inhibition of system A. Treatment with IL-1beta 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-1beta was abolished in the presence of IL-1beta 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-1beta treatment as evidenced by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. In rat placental brush border membrane vesicles isolated from IL-1beta-treated pregnant rats, system A activity was found to be decreased by approximately 40% compared to activity in control membrane vesicles.

CONCLUSIONS: IL-1beta 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-1beta.

Author-supplied keywords

  • Amino Acid Transport System A
  • Amino Acid Transport System A: physiology
  • Amino Acid Transport System ASC
  • Amino Acid Transport System ASC: physiology
  • Cultured
  • Cultured: pathology
  • Developmental
  • Female
  • Gene Expression Regulation
  • Humans
  • Interleukin-1
  • Interleukin-1: physiology
  • Messenger
  • Messenger: analysis
  • Pregnancy
  • Pregnancy: physiology
  • RNA
  • Trophoblasts
  • Trophoblasts: physiology
  • Tumor Cells
  • Uterine Neoplasms
  • Uterine Neoplasms: pathology

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  • Boonrit Thongsong

  • Radhika K Subramanian

  • Vadivel Ganapathy

  • Puttur D Prasad

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