Abstract 1636: Adverse Effect of Estrogen on Bone Morphogenetic Protein Receptor Signal Pathway in Pulmonary Arterial Endothelial Cells

Abstract

Gender differences in the development of Pulmonary Artery Hypertension (PAH) have been documented in both human and animal studies. In human, idiopathic PAH is predominantly a disease of young women in their child-bearing years, which suggests a role of female sex hormones in the pathogenesis of PAH. However, the effect of sex hormones on pulmonary vasculatures and the development of PAH has not been fully understood. Recent researches have revealed genetic predisposition such as BMPR (Bone Morphogenetic Protein Receptor). The aim of the present study is to investigate the effect of β-estradiol (E2) and oxygen concentration upon BMPR signal pathway in pulmonary arterial endothelial cells (PAEC) in vitro. Human and rat PAEC were cultured and we examined the expression of BMPR2, BMP-regulated Smads, and Id1 under 21% or 1% O 2 with BMP2 stimulation. Then, we investigate changes in the expression of these molecules in the presence of E2 with or without estrogen receptor antagonist (ICI 182.780.). First, we confirmed that estrogen receptor α and β were expressed in both PAECs. Second, we demonstrated that the expression of mRNA transcripts for BMPR2 and Id1 in PAEC was reduced after exposure to 24 hours’ hypoxia. In addition, E2 decreased the expression of phosphorylated Smad (p-Smad)1/5/8 in a dose-dependent manner (10 −10 M-10 −7 M) and p-Smad1/5/8 expression were decreased about 80% by 10 −7 M of E2. These attenuation of p-Smad1/5/8 expression were rescued by ICI182.780. Third, under normoxic condition with cobalt chloride or deferoxamine to prevent the degradation of HIF (hypoxia-inducible factor)-1α, the presence of E2 decreased the expression of p-Smad1/5/8 like under hypoxia. Conversely, administration of HIF-1α inhibitor (YC-1) canceled the reduced expression of p-Smad1/5/8 like under normoxia. Under hypoxia, the presence of E2 attenuates the BMPR signal pathway in PAEC in vitro. Our data indicated that the advance effect of E2 on BMPR signal pathway was associated with HIF-1α and estrogen receptor. Our observations provide the first evidence that female sex hormone affects on BMPR signal pathway, which can offer new strategies for the treatment of PAH.