G protein-coupled estrogen receptor 1 (GPER) mediates relaxation of coronary arteries via cAMP/PKA-dependent activation of MLCP


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


  • American Journal of Physiology Endocrinology and Metabolism


  • Am J Physiol Endocrinol Metab 307 (4): E398-E407


  • Activation of GPER exerts a protective effect in hypertension and ischemia-reperfusion models. 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 {mu}M), was associated with increased cAMP production in a concentration-dependent manner. Furthermore, inhibition of adenylyl cyclase (AC) with SQ-22538 (100 {mu}M) or inhibition of PKA activity with either Rp-8-CPT-cAMPS (5 {mu}M ) or PKI (5 μM) attenuated G-1-induced relaxation of coronary arteries preconstricted with PGF2{alpha} 1 {mu}M. G-1 also increased PKA activity in cultured coronary artery smooth muscle cells (SMC). We measured RhoA activity in cultured human and porcine coronary (SMC) and myosin light chain phosphatase (MLCP) activity in these artery rings by immunoblot analysis of phosphorylation of myosin-targeting subunit protein-1 (pMYPT-1, the MLCP regulatory subunit). G-1 decreased PGF2α induced pMYPT-1, while Rp-8-CPT-cAMPS prevented this inhibitory effect of G-1. Similarly, G-1 inhibited PGF2{alpha}-induced phosphorylation of MLC in coronary SMC, and this inhibitory effect was also reversed by Rp-8-CPT-cAMPS. RhoA activity was down regulated by G-1, whereas G36 (GPER antagonist) restored RhoA activity. Lastly, (100 {mu}M) FMP-API-1, an inhibitor of the interaction between PKA and A kinase anchoring protein (AKAP), attenuated the effect of G-1 on coronary artery relaxation and pMYPT-1. These findings demonstrate that localized cAMP/PKA signaling is involved in GPER-mediated coronary vasodilation by activating MLCP via inhibition of RhoA pathway.