Abstract 19226: 2-Methoxyestradiol Down-regulates Angiotensin Type 1 Receptor Through G protein Coupled Receptor 30 Dependent Epidermal Growth Factor Receptor Phosphorylation at Tyrosine 1148
The estrogen metabolite 2-methoxyestradiol (2ME2) elicits its pharmacological effects through G protein-coupled receptor 30 (GPR30), and has therapeutic potential in a number of cardiovascular disorders including hypertension. However, the exact mechanism of action remains unknown. Inhibiting angiotensin type 1 receptor (AT1R) has been shown to be critical for controlling hypertension and associated disorders. In this study, we have determined 2ME2 mediated AT1R and signaling pathways in primary aortic vascular smooth muscle cells. Cells exposed to 2ME2 for 24 h showed down-regulation of [3H] angiotensin II specific binding without any significance change in receptor affinity which was inhibited by losartan an AT1R specific antagonist. Upon 2ME2 treatment cells exhibited significant phosphorylation and nuclear translocation of extracellular-signal regulated kinase 1 and 2 (ERK1/2) and down-regulation of AT1R. In the absence of AG1478, an epidermal growth factor receptor (EGFR) selective inhibitor, 2ME2 increased EGFR phosphorylation at tyrosine 1148 a docking site for Src homology protein SHP1 necessary for ERK1/2 activation. The results indicate paracrine signaling of EGF participated in the regulation of AT1R down-regulation. In addition, Marimastat, a matrix metalloproteinase-9 (MMP9) specific inhibitor attenuated 2ME2 induced activation of EGFR and ERK1/2, and impeded AT1R down-regulation. In the presence of 2ME2 protein kinase C delta (PKCδ) translocated to the plasma membrane. When inhibited PKCδ with rottlerin 2ME2 mediated AT1R down-regulation was abrogated. Furthermore, we showed that activation of Src kinase was closely involved in this process. Finally, under similar conditions stimulation of GPR30 with the selective agonist G1 elicited related signaling pathway and down-regulated the AT1R expression which was reversible by GPR30 antagonist G15. Taken together, the study provides critical insights into the newly discovered role and signaling pathways of 2ME2 in the regulation of AT1R in vascular smooth muscle cells.
Author Disclosures: B. Ogola: None. Y. Zhang: None. T. Thekkumkara: None.
- © 2016 by American Heart Association, Inc.