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

项目总结/摘要 动脉硬化是衰老过程的标志。然而，过早硬化经常出现在 高血压、肥胖、胰岛素抵抗和2型糖尿病（T2 D）。男性和女性都受到影响，但 患有T2 D的女性风险更大。由于动脉僵硬度增加是 心血管疾病（CVD），胰岛素抵抗（IR）和肥胖女性对动脉粥样硬化的易感性增加， 硬化可以解释他们患心血管疾病的高风险。在健康女性中，通过雌激素受体的雌激素信号 α（ERα）防止僵硬，但这些作用在营养过剩和肥胖时， 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增加有助于动脉硬化和EC功能障碍，部分原因是 降低一氧化氮（NO）的生物利用度。醛固酮是一种主要的ENaC刺激，但其他类固醇激素， 特别是雌激素，也促进各种组织中ENaC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）通路。醛固酮升高，NO降低 生物利用度是肥胖、IR和T2 D女性的特征。根据我们之前的工作和最近的 根据初步数据，我们假设雌激素通过EC ERα上调EC ENaC表达 和活性，通过SGK-1，加重肥胖，IR绝经前女性的内皮和动脉硬化。 这一假设的推论是，ENaC抑制对肥胖者的动脉硬度有更大的影响， 绝经前IR女性肥胖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患者的动脉僵硬度产生更大的影响。 女性比肥胖、IR男性更易患病。我们将测量IR和肥胖EC特异性ERα的动脉/EC硬度， ENaC KO小鼠;在分离的EC中;以及在肥胖、IR女性（绝经前和绝经后）和年龄- 1）确定是否EC ERα调节EC ENaC，通过 SGK-1在女性IR中加速内皮和动脉硬化的发生中起重要作用 2）确定用ENaC抑制剂阿米洛利治疗是否改善内皮功能 和动脉僵硬度在肥胖IR受试者中的作用。迄今为止， EC ERα对ENaC表达/活化的调节，在随后的性别相关动脉僵硬度差异中， 肥胖和胰岛素抵抗，仍然没有被探索。这项提案旨在填补这一空白，并表明， ENaC激活在逆转血管内皮功能障碍和动脉硬化方面具有非凡的前景， 肥胖和胰岛素抵抗，并最终预防心血管疾病，特别是女性。

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.