Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Berghold, V.
Characterization of Phospholipid Scramblase 1 (PLSCR1) in the villous trophoblast of the human placenta
PhD-Studium (Doctor of Philosophy); Humanmedizin; [ Dissertation ] Medical University of Graz; 2014. pp. 95
[OPEN ACCESS]
FullText
- Autor*innen der Med Uni Graz:
- Berghold Veronika Marlies
- Betreuer*innen:
- Frank Sasa
- Gauster Martin
- Heinemann Akos
- Huppertz Berthold
- Altmetrics:
- Abstract:
- The outermost layer of the human placenta facing maternal blood is called syncytiotrophoblast, a multinucleated epithelial layer. This syncytiotrophoblast develops and grows by fusion with underlying mononucleated cytotrophoblasts. During the complex process of villous trophoblast fusion the cell membrane’s phospholipid asymmetry is abolished leading to phosphatidylserine exposure on the cell surface. Maintenance and transient abrogation of this membrane architecture is accomplished by different types of phospholipid transporters (flippases, floppases and scramblases). Initial microarray studies revealed phospholipid scramblase 1 (PLSCR1) to have the highest expression among possible candidates. Therefore, the aims of this study were to analyze the spatio-temporal expression of PLSCR1 in the human placenta and to further elucidate its putative role in trophoblast syncytialization. In first trimester and term placenta PLSCR1 was abundantly expressed in syncytiotrophoblast, macrophages and endothelial cells, while it was only slightly detected in cytotrophoblasts. For functional studies, BeWo cells, the generally accepted trophoblast-fusion model, primary trophoblasts isolated from term placentas and first trimester placental explant cultures were used. In BeWo cells PLSCR1 mRNA and protein expression remained constant even after stimulation with forskolin to form multinucleated syncytia. However, when primary trophoblasts were stimulated with Br-cAMP, a decrease in PLSCR1 mRNA and protein expression was detected. Two approaches with RNA interference and a scramblase inhibitor, R5421 (ethaninidothioic acid) were used to define the functional role of PLSCR1 in trophoblast fusion. No changes in fusion efficiency were observed in PLSCR1 siRNA down-regulated cells. On the contrary when PLSCR1 activity was inhibited with R5421 in BeWo cells increased GCM-1 mRNA expression, beta-subunit of human chorionic gonadotropin (beta-hCG) protein secretion and cell fusion rates were observed. R5421 treatment in primary trophoblasts and villous explant cultures had no effect on trophoblast fusion. In this study we focused on PLSCR1 localization and expression in the human placenta. The obtained results suggest a possible involvement of PLSCR1 in negatively regulating trophoblast fusion.