Notch Enhances Shear-mediated Arteriogenesis in Cerebral Vessels

Notch 增强脑血管中剪切介导的动脉生成

• 批准号: 8622212
• 负责人: Tyson Nam Kim
• 金额: $ 2.71万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-03-01 至 2014-06-13
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8622212
• 关键词: Ablation; Adult; American; Anatomy; Animals; Arterial Occlusive Diseases; Arteries; Biological; Biological Models; Blood; Blood Vessels; Blood flow; Brain; Canis familiaris; Carotid Arteries; Cerebrum; Development; Disease; Endothelial Cells; Endothelium; Enhancers; Environment; Fluorescence; Fluorescence Microscopy; Genetic; Glass; Goals; Growth; Human; Image; Immunofluorescence Immunologic; Implant; Injury; Knowledge; Ligands; Ligation; Liquid substance; Measurement; Measures; Mediating; Methods; Microscopy; Middle Cerebral Artery Occlusion; Molecular; Morbidity - disease rate; Morphology; Mus; Myocardial Infarction; Notch Signaling Pathway; Optics; Outcome; Pathway interactions; Phase; Physiology; Process; Reporter; Research; Research Design; Role; Scanning; Signal Transduction; Societies; Stroke; Surface; Surgical Models; Testing; Time; Tissues; Transgenic Organisms; analytical method; arteriole; artery occlusion; base; cerebrovascular; cranium; embryonic stem cell; experience; femoral artery; hemodynamics; improved; in vivo; interest; loss of function; middle cerebral artery; mortality; notch protein; programs; public health relevance; rapid growth; response; shear stress; therapeutic development; transcription factor; two-photon

DESCRIPTION (provided by applicant): Occlusive arterial disease remains the leading cause of mortality and morbidity in Americans and constitutes a tremendous financial burden to society. Arterial occlusion results in arteriogenesis, a process by which small collateral arterioles remodel into larger conduit arteries that reroute blood and improve flow to the ischemic tissue. The capacity of pre-existing collaterals and their growth following occlusion is strongly modulated by genetic background in both humans and mice, resulting in a wide range of outcomes. Increased hemodynamic shear stress in these collateral vessels promotes arteriogenesis but the molecular pathways and mechano-responses mediating this growth are not well understood. Notch receptor and ligand loss-of-function studies demonstrate that the Notch signaling pathway is necessary for arteriogenesis of pre- existing vessels. The goal of our study is to elucidate the mechanism by which endothelial Notch signaling is regulated after arterial occlusion and to establish a role for Notch signaling in enhancing arteriogenesis of cerebral collaterals after occlusive injury. We observe decreased cerebral arteriogenesis after arterial occlusion in mice with genetic ablation of Notch signaling in endothelial cells (ECs). Conversely, we observe impressive enlargement of cerebral collaterals following arterial occlusion in mice with expression of constitutively active Notch4 (Notch4*) in ECs. Our preliminary results suggest that arteriogenesis of cerebral collaterals occurs specifically in vessel segments that deliver increased flow to the region of injury. We hypothesize that increased hemodynamic shear stress activates endothelial Notch signaling, and that Notch is a necessary and potent enhancer of shear-induced arteriogenesis. In aim 1, we develop methods to dynamically study cerebral collateral enlargement and blood flow in the same animals over time by combining a surgical model for middle cerebral artery (MCA) ligation and intravital two-photon excited fluorescence microscopy. We generate new analytical methods to quantify hemodynamics and WSS with high accuracy and improvement over current approximations. In aim 2, we will determine if Notch signaling in ECs is activated by shear stress. We will use an in vivo reporter of canonical Notch signaling and immunofluorescence to determine when Notch is activated in endothelium after MCA ligation. We will determine whether Notch activation is limited to vessels with increased WSS, which we have observed is correlated with arteriogenesis. In aim 3, we will determine whether Notch signaling in ECs controls cerebral arteriogenesis through a shear-responsive program. Specifically, we will determine whether Notch signaling in ECs is critical for arteriogenesis after MCA ligation. We will also determine whether Notch4* in ECs is sufficient to enhance arteriogenesis after MCA ligation and if elevated WSS is also required. Upon completion of this project, we will have advanced the mechanistic understanding of Notch-mediated arteriogenesis. Knowledge gained from this study will help therapeutic development for disease associated with cerebral arterial occlusion. PUBLIC HEALTH RELEVANCE: Occlusive arterial disease, including stroke and heart attack, is the leading cause of mortality and morbidity in Americans. There is significant interest in developing molecular therapy to stimulate blood vessel growth and return blood flow to dying tissue. Our research may elucidate an important biological mechanism that controls artery growth, helping in the development of molecular treatments for occlusive arterial disease.

描述(申请人提供)：闭塞性动脉疾病仍然是美国人死亡和发病的主要原因，并对社会构成巨大的经济负担。动脉闭塞导致动脉生成，这是一个过程，通过这个过程，小的侧枝小动脉重新形成更大的管道动脉，从而改变血液的路线，改善对缺血组织的流动。在人类和小鼠中，预先存在的侧支的能力和它们在闭塞后的生长都受到遗传背景的强烈调节，导致了广泛的结果。这些侧支血管中血流动力学剪应力的增加促进了动脉的形成，但调节这种生长的分子途径和机械反应还不是很清楚。Notch受体和配体功能丧失的研究表明，Notch信号通路对于预先存在的血管的动脉形成是必要的。本研究的目的是阐明动脉闭塞后内皮细胞Notch信号的调控机制，并确定Notch信号在促进闭塞损伤后脑侧支动脉生成中的作用。我们通过基因消融内皮细胞(ECs)中的Notch信号，观察到动脉闭塞后小鼠脑动脉生成减少。相反，我们观察到动脉闭塞后血管内皮细胞表达固有活性Notch4(Notch4*)的小鼠大脑侧支显著扩张。我们的初步结果表明，脑侧支的动脉生成特别发生在向损伤区域输送更多血流的血管节段。我们假设血流动力学切应力的增加激活了内皮细胞的Notch信号，并且Notch是切变诱导的动脉形成的必要和有效的增强剂。在目标1中，我们发展了一种方法，通过结合大脑中动脉(MCA)结扎手术模型和活体双光子激发荧光显微镜，动态研究同一动物随时间的脑侧支扩大和血流量。我们产生了新的分析方法来量化血流动力学和WSS，具有高精度并改进了现有的近似方法。在目标2中，我们将确定内皮细胞中的Notch信号是否被剪应力激活。我们将使用规范的Notch信号和免疫荧光的体内报告来确定MCA结扎后内皮细胞Notch何时被激活。我们将确定Notch的激活是否仅限于WSS增加的血管，我们已经观察到这与动脉形成相关。在目标3中，我们将确定内皮细胞中的Notch信号是否通过剪切反应程序控制脑动脉的形成。具体地说，我们将确定内皮细胞中的Notch信号是否在MCA结扎后的动脉形成中起关键作用。我们还将确定内皮细胞中的Notch4*是否足以促进MCA结扎后的动脉生成，以及是否也需要增加WSS。这个项目完成后，我们将对Notch介导的动脉形成的机制有了更深入的了解。从这项研究中获得的知识将有助于脑动脉闭塞相关疾病的治疗发展。 公共卫生相关性：包括中风和心脏病发作在内的闭塞性动脉疾病是美国人死亡和发病的主要原因。人们对开发分子疗法以刺激血管生长并使血液回流到死亡组织有很大的兴趣。我们的研究可能会阐明控制动脉生长的重要生物学机制，有助于开发闭塞性动脉疾病的分子治疗方法。