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Membrane-bound progesterone receptor expression in human aortic endothelial cells
Brenda H Welter1, Elizabeth L Hansen, Karla J Saner
1Department of Microbiology and Molecular Medicine, Clemson University, Clemson, South Carolina, USA.
Summary
Researchers identified a novel membrane-bound progesterone receptor in human aortic endothelial cells. This receptor
Area of Science:
- Endocrinology
- Vascular Biology
- Cell Biology
Background:
- Estradiol and progesterone influence vasoreactivity.
- Progesterone exhibits non-genomic effects on vascular smooth muscle cells, inhibiting calcium influx.
- The specific receptors mediating these rapid vascular effects remain largely uncharacterized.
Purpose of the Study:
- To investigate the presence and localization of novel membrane-bound progesterone receptors in human aortic endothelial cells.
- To correlate the expression of these receptors with the cell cycle stage.
- To explore the potential role of these receptors in the non-genomic actions of progesterone.
Main Methods:
- Western blotting using antibodies against classic progesterone receptor domains.
- Differential centrifugation to isolate cellular membrane fractions.
- Immunofluorescence microscopy and ligand-binding assays for receptor visualization.
- Fluorescent activated cell sorting (FACS) to analyze receptor expression and cell cycle correlation.
Main Results:
- Novel progesterone receptor bands (100 and 60 kD) were detected in the membrane fraction of human aortic endothelial cells.
- These differed in molecular weight from classic nuclear progesterone receptors (B and A).
- Approximately 8% of cells expressed the plasma membrane progesterone receptor, with higher prevalence in the G2/M cell cycle phase.
Conclusions:
- A novel plasma membrane-bound progesterone receptor exists in human aortic endothelial cells.
- This receptor may mediate the rapid, non-genomic vascular effects of progesterone.
- Receptor expression is linked to the cell cycle, suggesting dynamic regulation.