Estrogen receptor-dependent attenuation of hypoxia-induced changes in the lung genome of pulmonary hypertension rats

17β-estradiol (E2) exerts complex and context-dependent effects in pulmonary hypertension. In hypoxia-induced pulmonary hypertension (HPH), E2 attenuates lung vascular remodeling through estrogen receptor (ER)-dependent effects; however, ER target genes in the hypoxic lung remain unknown. In order to identify the genome regulated by the E2-ER axis in the hypoxic lung, we performed a microarray analysis in lungs from HPH rats treated with E2 (75 mcg/kg/d) ± ER-antagonist ICI182,780 (3 mg/kg/d). Untreated HPH rats and normoxic rats served as controls. Using a false discovery rate of 10%, we identified a significantly differentially regulated genome in E2-treated vs. untreated hypoxia rats. Genes most up-regulated by E2 encoded matrix metalloproteinase 8, S100 calcium binding protein A8, and IgA Fc receptor; genes most down-regulated by E2 encoded olfactory receptor 63, secreted frizzled-related protein 2, and thrombospondin 2. Several genes affected by E2 changed in the opposite direction after ICI182,780 co-treatment, indicating an ER-regulated genome in HPH lungs. The bone morphogenetic protein antagonist Grem1 (gremlin 1) was up-regulated by hypoxia, but found to be among the most down-regulated genes after E2 treatment. Gremlin 1 protein was reduced in E2-treated vs. untreated hypoxic animals, and ER-blockade abolished the inhibitory effect of E2 on Grem1 mRNA and protein. In conclusion, E2 ER-dependently regulates several genes involved in proliferative and inflammatory processes during hypoxia. Gremlin 1 is a novel target of the E2-ER axis in HPH. Understanding the mechanisms of E2 gene regulation in HPH may allow for selectively harnessing beneficial transcriptional activities of E2 for therapeutic purposes.17β-雌二醇（17β-estradiol，E2）在肺动脉高压中发挥复杂且依赖于微环境的调控作用。在缺氧性肺动脉高压（hypoxia-induced pulmonary hypertension，HPH）模型中，E2可通过雌激素受体（estrogen receptor，ER）依赖的途径改善肺血管重构，但缺氧肺组织中的ER靶基因仍未明确。为鉴定缺氧肺组织中受E2-ER轴调控的差异基因集，我们对经E2（75 mcg/kg/d）联合或不联合雌激素受体拮抗剂ICI182,780（3 mg/kg/d）处理的HPH大鼠肺组织进行了基因芯片分析。以未处理的HPH大鼠及常氧大鼠作为对照。我们以10%的错误发现率（false discovery rate）作为筛选阈值，在E2处理组与未处理的缺氧大鼠肺组织中鉴定出显著差异表达的基因集。E2上调最为显著的基因包括基质金属蛋白酶8（matrix metalloproteinase 8）、S100钙结合蛋白A8（S100 calcium binding protein A8）及IgA Fc受体（IgA Fc receptor）；E2下调最为显著的基因则包括嗅觉受体63（olfactory receptor 63）、分泌型卷曲相关蛋白2（secreted frizzled-related protein 2）及血小板反应蛋白2（thrombospondin 2）。部分受E2调控的基因在联合ICI182,780处理后表达趋势发生逆转，这表明HPH肺组织中存在受ER调控的基因集。骨形态发生蛋白拮抗剂Grem1（gremlin 1）在缺氧环境下被上调，但经E2处理后成为下调最显著的基因之一。与未处理的缺氧动物相比，E2处理组的Grem1蛋白水平显著降低，而阻断ER可抵消E2对Grem1 mRNA及蛋白的抑制作用。综上，E2可通过ER依赖的方式调控缺氧过程中参与细胞增殖与炎症反应的多个基因。Grem1是HPH中E2-ER轴的新型靶标。阐明E2在HPH中的基因调控机制，或可实现针对性利用E2的有益转录活性以用于治疗目的。