Estrogen receptor alpha signaling in endothelial cells exacerbates arterial stiffening via upregulation of ENaC in insulin resistant females

项目概要/摘要 动脉硬化是衰老过程的一个标志。然而，过早硬化常见于 高血压、肥胖、胰岛素抵抗和 2 型糖尿病 (T2D)。男性和女性都会受到影响，但是 患有 T2D 的女性面临更大的风险。由于动脉僵硬度增加是一个独立的预测因子 心血管疾病（CVD）、胰岛素抵抗（IR）和肥胖女性对动脉的易感性增加 身体僵硬可能是其罹患 CVD 风险较高的原因。在健康女性中，雌激素信号通过雌激素受体传递 α (ERα) 可以防止肌肉僵硬，但当存在 ERα 时，这些作用在营养过剩和肥胖中会减弱。 ERα 的变化可能是有害的。内皮细胞 (EC) 上皮钠通道 (ENaC) 表达增加 肥胖和 IR 雌性小鼠。 EC ENaC 增加会导致动脉硬化和 EC 功能障碍，部分原因是 降低一氧化氮（NO）的生物利用度。醛固酮是主要的 ENaC 刺激物，但其他类固醇激素， 特别是雌激素，还促进 ENaC 在各种组织中的表达/功能。 ENaC 活性受以下因素调节 血清糖皮质激素诱导激酶 1 (SGK-1) 途径。醛固酮升高，NO 降低 生物利用度是肥胖、IR 和 T2D 女性的特征。根据我们之前的工作和最近的工作 根据初步数据，我们的假设是雌激素通过 EC ERα 的作用上调 EC ENaC 表达 SGK-1 的活性会加剧肥胖、IR 绝经前女性的内皮和动脉硬化。 这一假设的推论是 ENaC 抑制将对肥胖者的动脉僵硬度产生更大的影响， 绝经前 IR 女性高于肥胖 IR 绝经后女性或年龄匹配的肥胖 IR 男性。 因此，ENaC 抑制将对绝经前肥胖、IR 的动脉僵硬度产生更大影响 女性多于肥胖、IR 男性。我们将测量 IR 和肥胖 EC 特异性 ERα 中的动脉/EC 硬度，以及 ENaC KO 小鼠；在孤立的 EC 中；在一组肥胖、IR 女性（绝经前和绝经后）和年龄- 匹配的男性，以实现以下目标：1) 确定 EC ERα 是否对 EC ENaC 进行调节，通过 SGK-1，在 IR 女性加速内皮和动脉硬化的发生中起重要作用 小鼠和 2) 确定 ENaC 抑制剂阿米洛利治疗是否可以改善内皮功能 一项随机安慰剂对照试验中肥胖 IR 受试者的动脉硬化。迄今为止，具体作用 EC ERα 对 ENaC 表达/激活的调节，导致动脉僵硬度的性别相关差异 肥胖和胰岛素抵抗的关系尚未得到探索。该提案旨在填补这一空白并表明目标 ENaC 激活在逆转内皮功能障碍和动脉僵化方面具有非凡的前景 肥胖和胰岛素抵抗，最终预防心血管疾病，尤其是女性。

Project Summary/Abstract Arterial stiffening is a hallmark of the aging process. However, premature stiffening is often seen in hypertension, obesity, insulin resistance, and type 2 diabetes (T2D). Both men and women are affected, but women with T2D are at greater risk. As augmented arterial stiffness is an independent predictor of cardiovascular disease (CVD), the increased susceptibility of insulin-resistant (IR) and obese women to arterial stiffening may explain their higher risk for CVD. In healthy women, estrogen signaling via estrogen receptor alpha (ERα) prevents stiffening, but these effects are blunted in over-nutrition and obesity when the presence of the ER may be deleterious. Endothelial cell (EC) epithelial sodium channel (ENaC) expression increases in obese and IR female mice. Increased EC ENaC contributes to arterial stiffening and EC dysfunction, in part by lowering nitric oxide (NO) bioavailability. Aldosterone is a major ENaC stimulus, but other steroid hormones, specifically estrogen, also promote ENaC expression/function in various tissues. ENaC activity is regulated by the serum glucocorticoid inducible-kinase 1 (SGK-1) pathway. Elevated aldosterone and decreased NO bioavailability are characteristics of obese, IR and T2D women. Based on our prior work and most recent preliminary data, our hypothesis is that estrogen action through the EC ERα upregulates EC ENaC expression and activity, via SGK-1, exacerbating endothelial and arterial stiffening in obese, IR premenopausal females. The corollary to this hypothesis is that ENaC inhibition will have a greater impact on arterial stiffness in obese, premenopausal IR women than in obese IR postmenopausal women or age-matched obese, IR men. Consequently, ENaC inhibition will have a greater impact on arterial stiffness in premenopausal obese, IR women than in obese, IR men. We will measure arterial/EC stiffness in IR and obese EC-specific ERα and ENaC KO mice; in isolated ECs; and in a cohort of obese, IR women (pre and post-menopausal) and age- matched men, to accomplish the following Aims: 1) To determine whether EC ERα regulation of EC ENaC, via SGK-1, plays an important role in the genesis of accelerated endothelial and arterial stiffening in IR female mice and 2) to determine whether treatment with the ENaC inhibitor, amiloride, improves endothelial function and arterial stiffness in obese IR subjects in a randomized placebo-controlled trial. To date, the specific role of EC ERα regulation of ENaC expression/activation, in ensuing sex-related differences in arterial stiffness in obesity and insulin resistance, remains unexplored. This proposal aims to fill that gap and show that targeting ENaC activation holds extraordinary promise in reversing endothelial dysfunction and arterial stiffness in obesity and insulin resistance, and ultimately preventing cardiovascular disease, especially in women.