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A New Luciferase-Based Quantitative Assay for the Evaluation of Human Trophoblast Fusion

Abstract

The syncytiotrophoblast is a multinuclear cell layer maintained through fusion events with cytotrophoblasts and plays a key role in the properties of the placenta. Monitoring fusion in this cell layer is important in studies aimed at understanding its function. We herein propose a new fusion assay based on the transactivating potential of the human immunodeficiency virus type 1 (HIV-1) Tat protein on its promoter present in the long terminal repeat (LTR) region. We used 2 BeWo cell populations, one stably transfected with the HIV-1 LTR positioned upstream of the luciferase gene and the other stably transfected with a Tat expression vector. Both stable cell lines were responsive to Tat-mediated LTR transactivation and demonstrated normal fusion and human chorionic gonadotropin (hCG) secretion upon stimulation. When both BeWo cell lines were cocultured, forskolin-mediated induction of fusion led to an increase in luciferase activity, which was sensitive to anti-syncytin 1 and -2 antibodies and syncytin 2 small interfering RNAs (siRNAs). Similar results were obtained in primary trophoblasts. Our results highlight the effectiveness and accuracy of this new quantification assay for trophoblast fusion.

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Correspondence to Benoit Barbeau PhD.

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Vargas, A., Larocque, É., Toufaily, C. et al. A New Luciferase-Based Quantitative Assay for the Evaluation of Human Trophoblast Fusion. Reprod. Sci. 19, 374–382 (2012). https://doi.org/10.1177/1933719111424437

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Keywords

  • cell fusion
  • human trophoblasts
  • syncytin 1
  • syncytin 2
  • luciferase
  • HIV-1 Tat