Progesterone Regulates Endothelin Receptor-A Expression

Objective: Endothelin-A receptor (Ednra) is expressed in cephalic and cardiac neural crest cells during embryonic development. This gene is also associated with different pathological conditions such as high blood pressure, pulmonary hypertension, cancer, periodontal disease, eclamptic pregnancy and premature delivery. Despite the important roles of the receptor, the mechanisms regulating its expression are unknown. Previously, we have shown that progesterone is a potential regulator of Ednra expression and identified a conserved region (-5.7kb to -4.2kb) responding to progesterone. In this study, we investigate how progesterone regulates Ednra expression. Method: The conserved sequence was analyzed using the MatInspector and TESS programs to identify progesterone response elements (PRE) and other regulatory elements. Binding of the liganded progesterone receptor B (PRB) to these sites was confirmed by ChIP assay and the functional analyses of these PRE was done by site-directed mutagenesis and luciferase assays. Result: The conserved sequence analyses revealed the presence of 6 classical PRE (PRE1 to 6). Our ChIP assay results revealed that PRB in presence of progesterone can bind all these elements with the exception of PRE2, confirming that progesterone is needed to activate Ednra expression.  The mutation analyses revealed that PRE1 (-5572 to -5567) and particularly PRE6 (-4658 to -4653) were important but these mutations could not completely abolish Ednra expression. The other sites had no or little effects on Ednra expression. We uncovered that progesterone was also controlling Ednra expression through a non-classical mechanism using a GATA2 site that when mutated along with PRE6, abolished Ednra expression. Conclusion: Progesterone regulates Ednra expression through classical and non-classical mechanisms. These results suggest that while Ednra may be part of the molecular mechanisms linking problematic pregnancy and periodontitis associated with pregnancy, mechanisms controlling its expression are complex. Supported by NIH/ NIDCR U24DE16472 (LBR) and T32-DE018380 (YZ).