Network signature of low-flow endothelial dysfunction

项目概要/摘要 内皮细胞是血管稳态的重要调节者，内皮功能障碍是血管内皮疾病的一个标志。 心血管疾病。寻找新疗法的挑战是找到早期控制点来预防 向广泛的病理信号传导谱的转变并破坏内皮网络。采用新颖的成像和 通过分析方法，我们已经确定了沿着血管内膜的动态 Ca2 信号传导的离散模式 它是血管功能的基础，并指导主要血管反应的特异性、敏感性和强度。 这些模式由动态事件参数（频率、幅度、持续时间和空间）的配置文件定义 传播），沿着内皮网络形成独特的特征。内皮 Ca2 事件的复杂谱 （从孤立的短暂瞬变到广泛的多细胞波）是由之间的正反馈相互作用产生的 质膜 TRP 通道（Ca2 进入）和内质网 IP3R（Ca2 释放）。小号 电导 Ca2 激活的 K 通道 (KCa) 通过发挥 Ca2 依赖性，在此信号传导中发挥关键作用 超极化和放大 Ca2+ 通过 TRP 通道的流入（特别是流体剪切应力 (FSS)- 激活 TRPV4 通道）。在患有外周动脉疾病的患者的血流剥夺的远端动脉中， 内皮细胞表现出独特的截断 Ca2 特征，其特征是空间受限的小振幅 瞬变。这种异常的 Ca2 分布早期出现在低流量颈动脉结扎小鼠模型中，导致 内皮功能障碍和血管重塑。这些低流量适应涉及逐渐丧失 内皮 KCa2.3 通道并表明 KCa/TRPV4 协同作用的早期丧失。我们假设 在低 FSS 条件下 TRPV4-KCa2.3 信号传导的破坏会导致进行性、高度 限制内皮 Ca2 信号，促进内皮功能障碍和血管重塑。 目标 1 将描述 TRPV4-KCa2.3 信号传导在动脉生理 Ca2 信号中的作用 内皮细胞。我们将进行共焦成像（采用新颖的高内涵分析）并采用内皮细胞 特定敲除小鼠（ecKCa2.3-/- 和 ecTRPV4-/-）以及人类外周动脉以阐明合作 差分 FSS 下的通道影响。目标 2 将确定低/振荡 FSS 是否会导致截断 TRPV4-KCa2.3 依赖的内皮 Ca2 信号导致内皮功能障碍和血管 重塑。我们将采用部分结扎小鼠模型来评估 TRPV4-的强度和时间进程 KCa2.3 对 Ca2 信号传导、血管反应性和血管壁增厚的特异性影响。目标 3 将决定 保留内皮 TRPV4-KCa2.3 Ca2 信号传导是否可以改善功能性和功能性发育 慢性低流量导致的结构性血管变化。我们还将评估是否采取干预措施来保护 Ca2 信号直接减轻低流量的病理影响。

PROJECT SUMMARY/ABSTRACT The endothelium is a crucial regulator of vascular homeostasis and endothelial dysfunction is a hallmark of cardiovascular disease. The challenge in searching for new therapies is finding early control points that prevent the shift to broad pathologic signaling profiles and disrupt the endothelial network. Employing novel imaging and analysis approaches, we have identified discrete patterns of dynamic Ca2+ signalling along the vascular intima that underlie vascular function and direct the specificity, sensitivity and intensity of prevailing vascular responses. These patterns, defined by profiles of dynamic event parameters (frequency, amplitude, duration and spatial spread), form distinct signatures along the endothelial network. The complex spectrum of endothelial Ca2+ events (from isolated brief transients to broad multicellular waves) result from positive feedback interaction between plasma membrane TRP channels (Ca2+ entry) and endoplasmic reticulum IP3Rs (Ca2+ release). Small conductance Ca2+-activated K+ channels (KCa) play a key role in this signaling by exerting Ca2+-dependent hyperpolarization and amplifying Ca2+ influx through TRP channels (particularly fluid shear stress (FSS)- activated TRPV4 channels). In flow-deprived distal arteries from patients with peripheral artery disease, the endothelium exhibits a distinctive truncated Ca2+ signature characterized by spatially restricted small amplitude transients. This anomalous Ca2+ profile appears early in a low-flow carotid ligation mouse model, giving rise to endothelial dysfunction and vascular remodelling. These low-flow adaptations involve progressive loss of endothelial KCa2.3 channels and suggest an early loss of cooperative KCa/TRPV4 action. We hypothesize that disruption of TRPV4-KCa2.3 signaling under conditions of low FSS causes a progressive, highly restricted endothelial Ca2+ signature that promotes endothelial dysfunction and vascular remodeling. Aim 1 will characterize the role of TRPV4-KCa2.3 signaling in physiologic Ca2+ signatures along the arterial endothelium. We will conduct confocal imaging (with novel high-content analysis) and employ endothelium- specific knockout mice (ecKCa2.3-/- and ecTRPV4-/-) as well as human peripheral arteries to elucidate cooperative channel impacts under differential FSS. Aim 2 will determine whether low/oscillatory FSS causes truncation of the TRPV4-KCa2.3-dependent endothelial Ca2+ signature that leads to endothelial dysfunction and vascular remodeling. We will employ a partial ligation mouse model to assess the magnitude and time course of TRPV4- KCa2.3-specific impacts on Ca2+ signaling, vasoreactivity and vascular wall thickening. Aim 3 will determine whether preservation of endothelial TRPV4-KCa2.3 Ca2+ signaling ameliorates development of functional and structural vascular changes resulting from chronic low flow. We will also assess whether interventions to preserve the Ca2+ signature directly abate pathologic impacts of low flow.