Steagall Rebecca J, Yao Fanrong, Shaikh Saame Raza, Abdel-Rahman Abdel A
Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA.
Department of Biochemistry and Molecular Biology, East Carolina Diabetes & Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA.
Life Sci. 2017 Aug 1;182:41-49. doi: 10.1016/j.lfs.2017.06.005. Epub 2017 Jun 6.
Little is known about the role of subcellular trafficking of estrogen receptor (ER) subtypes in the acute estrogen (E)-mediated alleviation of oxidative stress. We tested the hypothesis that ERα migration to the cardiac myocyte membrane mediates the acute E-dependent improvement of cellular redox status.
Myocardial distribution of subcellular ERα, ERβ and G-protein coupled estrogen receptor (GPER) was determined in proestrus sham-operated (SO) and in ovariectomized (OVX) rats, acutely treated with E (1μg/kg) or a selective ERα (PPT), ERβ (DPN) or GPER (G1) agonist (10μg/kg), by immunofluorescence and Western blot. We measured ROS and malondialdehyde (MDA) levels, and catalase and superoxide dismutase (SOD) activities to evaluate myocardial antioxidant/redox status.
Compared with SO, OVX rats exhibited higher myocardial ROS and MDA levels, reduced catalase and SOD activities, along with diminished ERα, and enhanced ERβ and GPER, localization at cardiomyocyte membrane. Acute E or an ERα (PPT), but not ERβ (DPN) or GPER (G1), agonist reversed these responses in OVX rats and resulted in higher ERα/ERβ and ERα/GPER ratios at the cardiomyocytes membrane. PPT or DPN enhanced myocardial Akt phosphorylation. We present the first evidence that preferential aggregation of ERα at the cardiomyocytes plasma membrane is ERα-dependent, and underlies E-mediated reduction in oxidative stress, at least partly, via the enhancements of myocardial catalase and SOD activities in OVX rats.
The findings highlight ERα agonists as potential therapeutics for restoring the myocardial redox status following E depletion in postmenopausal women.
关于雌激素受体（ER）亚型的亚细胞转运在急性雌激素（E）介导的氧化应激缓解中的作用，目前所知甚少。我们检验了以下假设：ERα向心肌细胞膜的迁移介导了急性E依赖性的细胞氧化还原状态改善。
通过免疫荧光和蛋白质印迹法，测定动情前期假手术（SO）和卵巢切除（OVX）大鼠心肌中亚细胞ERα、ERβ和G蛋白偶联雌激素受体（GPER）的分布，这些大鼠分别接受E（1μg/kg）或选择性ERα激动剂（PPT）、ERβ激动剂（DPN）或GPER激动剂（G1）（10μg/kg）的急性处理。我们测量了活性氧（ROS）和丙二醛（MDA）水平，以及过氧化氢酶和超氧化物歧化酶（SOD）活性，以评估心肌抗氧化/氧化还原状态。
与SO大鼠相比，OVX大鼠心肌ROS和MDA水平更高，过氧化氢酶和SOD活性降低，同时ERα在心肌细胞膜的定位减少，而ERβ和GPER增加。急性E或ERα激动剂（PPT），而非ERβ激动剂（DPN）或GPER激动剂（G1），可逆转OVX大鼠的这些反应，并导致心肌细胞膜上ERα/ERβ和ERα/GPER比值升高。PPT或DPN可增强心肌Akt磷酸化。我们首次证明，ERα在心肌细胞质膜上的优先聚集是依赖于ERα的，并且至少部分地通过增强OVX大鼠心肌过氧化氢酶和SOD活性，成为E介导的氧化应激降低的基础。
这些发现突出了ERα激动剂作为绝经后女性E缺乏后恢复心肌氧化还原状态的潜在治疗药物。
