Functional implications of fluid shear stress-induced mitochondrial remodeling

 描述(申请人提供)：增强血管系统中线粒体的结构和功能完整性的概念已经成为血管功能障碍的一种新的保护机制。然而，关于导致血管线粒体重塑的确切分子事件，有一个关键的知识缺口。我们的初步数据提供了令人信服的证据，证明血管保护性单向层流(h-flow)刺激线粒体的生物发生、融合/分裂动力学、线粒体DNA质量控制机制，并保护内皮免受氧化损伤、细胞衰老和炎症激活。在这个方案中，我们扩展了这一概念，并建议确定剪切敏感性线粒体重塑的关键分子介体(S)。抑癌基因P53通过定位于线粒体来调节线粒体功能，增强线粒体蛋白的线粒体DNA转录调控。在这一应用中，我们提出的数据表明，P53的线粒体定位对于切应力反应和线粒体DNA完整性特别重要。长期目标是确定h-flow维持血管壁线粒体动平衡的分子机制及其在预防内皮功能障碍和高血压血管功能障碍中的功能后果。因此，这项拟议的研究的目的是确定剪切力反应和线粒体生物发生调节内皮功能的分子机制，并检验对线粒体功能障碍的抵抗力增强将改善高血压发展的工作假说。我们的中心假设是，剪切力反应的诱导和由此产生的线粒体重塑将调节内皮氧化剂调节和对血管功能障碍的抵抗。为了验证这一假说，我们提出了以下具体目标：目的1.研究切应力诱导的线粒体重塑预防内皮功能障碍和高血压的机制。1A：验证P53在h-flow诱导的内皮线粒体重塑中所必需的假说。1B：确定内源性P53在体内血流依赖性线粒体重塑中的作用。目的2.确定将P53定向到线粒体内的细胞机制和治疗潜力。抑制线粒体DNA突变。目的：研究靶向差异定位P53基因对线粒体DNA稳定性和线粒体生物发生的影响。我们将建立针对线粒体(I)外膜、(II)内膜或(III)基质的线粒体靶向P53的模型，并量化线粒体的生物发生和线粒体DNA的完整性。2B：探讨线粒体P53蛋白的增加在线粒体DNA完整性、抵抗血管内皮细胞功能障碍和血管紧张素Ⅱ诱导的高血压中的作用。他提出的研究具有创新性，因为该项目的完成将为血流动力学切应力在内皮线粒体网络中的作用增加一个全新的维度，并提供线粒体、氧化应激和血管生物学之间的接口。

 DESCRIPTION (provided by applicant): The concept of enhancing structural and functional integrity of mitochondria in the vasculature has emerged as a novel protective mechanism for vascular dysfunction. However, there is a key knowledge gap with respect to the precise molecular events that are responsible for the vascular mitochondrial remodeling. Our preliminary data provide compelling evidence that vasoprotective unidirectional laminar flow (h-flow) stimulates mitochondrial biogenesis, fusion/fission dynamics, mitochondrial DNA quality control mechanisms and protects the endothelium from oxidative damages, cell senescence and inflammatory activation. In this proposal, we extend this concept and propose to determine the key molecular mediator(s) of the shear sensitive mitochondrial remodeling. The tumor suppressor p53 modulates mitochondrial function by localizing to mitochondria, enhancing mtDNA transcriptional regulation of mitochondrial proteins In this application, we present data that mitochondrial localization of p53 is particularly important for shear stress response and mtDNA integrity. The long-term goal is to determine molecular mechanisms by which h-flow maintains mitochondrial homeostasis in the blood vessel wall and its functional consequence in preventing endothelial dysfunction and hypertensive vascular dysfunction. The objective of this proposed study, therefore, is to determine the molecular mechanisms whereby shear stress response and mitochondrial biogenesis modulate endothelial function and test the working hypothesis that improved resistance to mitochondrial dysfunction will ameliorate the development of hypertension. Our central hypothesis is that induction of the shear stress response and resultant mitochondrial remodeling will modulate endothelial oxidant regulation and resistance to vascular dysfunction. To test this hypothesis we propose the following specific aims: AIM 1. Investigate the mechanism whereby shear stress-induced mitochondrial remodeling prevents endothelial dysfunction and hypertension. 1A: To test the hypothesis that p53 is required for h-flow-induced endothelial mitochondrial remodeling. 1B: To determine the role of endogenous p53 in flow-dependent mitochondrial remodeling in vivo. AIM 2. Determine cellular mechanisms and therapeutic potential of directing p53 to mitochondrial compartments. and suppressing mtDNA mutagenesis. 2A: To determine the effect of differentially targeted mitochondrial localization of p53 on mtDNA stability and mitochondrial biogenesis. We will model mitochondrial targeted p53 directing to mitochondrial (i) outer membrane, (ii) inner membrane or (iii) matrix and quantify mitochondrial biogenesis and mtDNA integrity. 2B: To investigate the role of increased mitochondrial p53 on mtDNA integrity and resistance to endothelial dysfunction and hypertension induced by AngII. T his proposed study is innovative because the completion of this project will add an entirely new dimension to the role of hemodynamic shear stress in the endothelial mitochondrial network and provide an interface between mitochondria, oxidant stress and vascular biology.