G protein-coupled estrogen receptor 1 mediates relaxation of coronary arteries via cAMP/PKA-dependent activation of MLCP. Academic Article uri icon

abstract

  • Activation of GPER exerts a protective effect in hypertension and ischemia-reperfusion models and relaxes arteries in vitro. However, our understanding of the mechanisms of GPER-mediated vascular regulation is far from complete. In the current study, we tested the hypothesis that GPER-induced relaxation of porcine coronary arteries is mediated via cAMP/PKA signaling. Our findings revealed that vascular relaxation to the selective GPER agonist G-1 (0.3-3 M) was associated with increased cAMP production in a concentration-dependent manner. Furthermore, inhibition of adenylyl cyclase (AC) with SQ-22536 (100 M) or of PKA activity with either Rp-8-CPT-cAMPS (5 M) or PKI (5 M) attenuated G-1-induced relaxation of coronary arteries preconstricted with PGF2 (1 M). G-1 also increased PKA activity in cultured coronary artery smooth muscle cells (SMCs). To determine downstream signals of the cAMP/PKA cascade, we measured RhoA activity in cultured human and porcine coronary SMCs and myosin-light chain phosphatase (MLCP) activity in these artery rings by immunoblot analysis of phosphorylation of myosin-targeting subunit protein-1 (p-MYPT-1; the MLCP regulatory subunit). G-1 decreased PGF2-induced p-MYPT-1, whereas Rp-8-CPT-cAMPS prevented this inhibitory effect of G-1. Similarly, G-1 inhibited PGF2-induced phosphorylation of MLC in coronary SMCs, and this inhibitory effect was also reversed by Rp-8-CPT-cAMPS. RhoA activity was downregulated by G-1, whereas G36 (GPER antagonist) restored RhoA activity. Finally, FMP-API-1 (100 M), an inhibitor of the interaction between PKA and A-kinase anchoring proteins (AKAPs), attenuated the effect of G-1 on coronary artery relaxation and p-MYPT-1. These findings demonstrate that localized cAMP/PKA signaling is involved in GPER-mediated coronary vasodilation by activating MLCP via inhibition of RhoA pathway.

published proceedings

  • Am J Physiol Endocrinol Metab

author list (cited authors)

  • Yu, X., Li, F., Klussmann, E., Stallone, J. N., & Han, G.

complete list of authors

  • Yu, Xuan||Li, Fen||Klussmann, Enno||Stallone, John N||Han, Guichun

publication date

  • January 1, 2014 11:11 AM