Endothelial biomechanics in vascular aging

内皮生物力学在多种内皮功能中起着关键作用。我们早先的研究发现 体外氧化脂质和体内血脂异常通过CD36清除剂诱导内皮细胞明显硬化 氧合甾醇的受体和掺入。最近，我们发现老化的大动脉内皮细胞硬化。 关键依赖于CD36和空泡蛋白Caveolin-1(Cav1)。我们的长期目标是阐明 增龄引起血管内皮细胞生物力学改变的机制及确定 这些机制对内皮功能障碍的贡献。在目前的提案中，我们解决了三个目标： 在目标1中，我们致力于阐明AGE诱导的内皮细胞僵硬的机制。首先(1A)，我们将确定 血管内皮细胞特异性CD36和/或Cav1的缺失是否能阻止中老年患者的血管内皮细胞硬化 (10-12月龄)和高龄(20-24月龄)小鼠以及是否表达/膜 这些蛋白质的定位会随着年龄的变化而改变。然后(1B)，我们将提供全面的脂质组学分析 动脉组织中脂质成分随年龄的变化，并识别积累的特定脂质种类 随着年龄的增长，并诱导内皮细胞硬化。在目标2中，我们重点研究与年龄相关的肌动蛋白重塑和破坏 内皮屏障的完整性。首先(目标2A)，我们将确定内皮细胞CD36和Cav1以及 CD36/Cav1介导的氧化脂质摄取在年龄相关肌动蛋白重塑、连接形态、 内皮对大分子的通透性，单核细胞的渗透。在目标(2B)的第二部分中， 我们将研究氧化类脂，特别是氧化类固醇诱导肌动蛋白的分子机制。 重塑，专注于一个新的假设，即氧固醇与RhoA竞争结合RhoA抑制物 蛋白质，GDI-1。在目标3中，这些研究被扩展到调查CD36/Cav1/Oxsterol- 依赖内皮细胞僵硬导致核形态扭曲、DNA损伤和核 机械敏感转录因子(3A)的移位和氧固醇诱导的假说 内皮僵硬通过破坏称为肌动蛋白帽的核周结构而导致核扭曲 (3B)。然后将这些研究扩展到比较分析的探索性子目标(3C 体内老化内皮细胞和氧化脂质暴露的内皮细胞转录水平的变化 诱导内皮细胞僵硬。这些目标是通过内皮特异性功能丧失(CD36和 Cav1)和功能获得(Cav1)遗传小鼠模型。原子力显微镜与脂类的结合 质谱学、机器学习算法分析的高分辨率共聚焦成像和其他状态- 最先进的实验方法。综上所述，这些研究有望提供重要的新的 我们对血管老化中内皮细胞硬化机制的理解 以及脂质诱导的内皮细胞硬化在年龄相关屏障破坏和核异常中的作用。

Endothelial biomechanics plays a key role in multiple endothelial functions. Our earlier studies discovered that oxidized lipids in vitro and dyslipidemia in vivo induce significant endothelial stiffening via CD36 scavenger receptor and incorporation of oxysterols. Most recently, we found that endothelial stiffening in aging aortas critically depends on CD36 and the caveolar protein, Caveolin-1 (Cav1). Our long term goal is to elucidate the mechanisms responsible for age-induced changes in endothelial biomechanics and to determine the contribution of these mechanisms to endothelial dysfunction. In the current proposal, we address three goals: In Aim 1, we focus on elucidating the mechanism of age-induced EC stiffening. First (1A), we will determine whether endothelial-specific deletions of CD36 and/or Cav1 prevent endothelial stiffening in moderately aged (10-12 months old) and advanced aged (20-24 months old) mice and whether expression/membrane localization of these proteins is altered by age. Then (1B), we will provide a comprehensive lipidomics analysis of changes in lipid composition in arterial tissues with age and identify specific lipid species that accumulate with age and induce endothelial stiffening. In Aim 2, we focus on age-related actin remodeling and disruption of endothelial barrier integrity. First (aim 2A), we will determine the roles of endothelial CD36 and Cav1 and CD36/Cav1-mediated uptake of oxidized lipids in age-related actin remodeling, junctional morphology, endothelial permeability to macromolecules, and infiltration of monocytes. In the second part of the aim (2B), we will investigate the molecular mechanisms by which oxidized lipids, particularly oxysterols, induce actin remodeling, focusing on a novel hypothesis that oxysterols compete with RhoA for binding to a RhoA inhibitory protein, GDI-1. In Aim 3, these studies are extended to investigate the impact of CD36/Cav1/oxysterol- dependent endothelial stiffening in inducing distortion of nuclear morphology, DNA damage and nuclear translocation of mechanosensitive transcription factors (3A) and explore the hypothesis that oxysterol-induced endothelial stiffening results in nuclei distortion by disruption of a peri-nuclear structure called the actin cap (3B). These studies are then extended to an exploratory sub-aim (3C) of comparative analysis of transcriptomic changes in aged endothelium in vivo and in endothelial cells exposed to oxidized lipids that induce endothelial stiffening. These goals are achieved using endothelial-specific loss of function (CD36 and Cav1) and gain of function (Cav1) genetic mouse models. A combination of Atomic Force Microscopy, lipid mass-spectrometry, high resolution confocal imaging analyzed by machine-learning algorithms and other state- of-the-art experimental approaches. Taken together, these studies are expected to provide significant new insights into our understanding of the mechanisms responsible for endothelial stiffening in aging vasculature and the role of lipid-induced endothelial stiffening in age-related barrier disruption and nuclei abnormalities.