Adducin, actin cytoskeleton and cognitive impairments

项目摘要/摘要 高血压是脑血管疾病和认知障碍的主要危险因素之一，尤其是 随着年龄的增长。尽管老年高血压患者表现出肌源性反应(MR)和自身调节功能受损 脑血流量、相关基因和机制及其在高血压中的作用 痴呆症还没有完全阐明。此提案是我的R21申请(AG050049)资助的直接扩展 在NIA ASG中，我们开发了动物模型来研究Add3在调节认知方面的作用 随着年龄的增长而出现的损伤。我们的遗传分析涉及社区神经认知中的动脉粥样硬化风险 研究表明，伽马-内收蛋白(ADD3)的变异与痴呆症有关。在动物研究中，我们 对FHH大鼠的Add3基因突变进行了基因定位，该突变会损害大脑MR和自我调节。在.期间 在R21期，我们产生并鉴定了ADD3转基因大鼠，并证实减少了 ADD3的表达是脑血流动力学受损的驱动力，从而导致血脑 屏障(BBB)渗漏、炎症，最终导致海马神经元和认知功能的丧失 衰老和高血压。我们新的初步数据表明，下调Add3会损害肌动蛋白 细胞骨架结构，降低肌动蛋白的稳定性，并增加初级大脑中超氧化物的产生 从FHH大鼠分离VSMCs。在ADD3处理的神经胶质细胞中也观察到同样的结构变化 DsiRNA。此外，FHH大鼠脑内Aβ蛋白的表达早在8周龄时就开始增加。 高血压FHH大鼠脑内毛细血管渗漏周围存在线粒体损伤。线粒体 在用Add3 DsiRNA处理的神经胶质细胞中，呼吸和ATP的产生受到影响。基于这一证据， 我们假设ADD3的表达减少，解偶联与膜上锚定的F-肌动蛋白，并增强 肌动蛋白聚合异常，损害脑血流量自动调节，促进认知发育 老年性高血压通过减轻脑血管细胞收缩、降低胶质Aβ清除而受损 并加重脑血管线粒体功能障碍。我们将ADD3基因KO大鼠用于正常SD 确定肌动蛋白聚合增强是否改变MR的遗传背景和药物干预 这可以解释脑血流自动调节功能受损、血脑屏障渗漏、神经变性以及 痴呆症。我们还将确定是否存在Aβ清除减少和脑血管线粒体 ADD3KO大鼠的功能障碍。这项拟议研究的结果将证实，老年高血压 促进受损的CBF自动调节，导致认知缺陷。未被发现的机制将 解决关键的知识差距，以更好地了解ADD3下调是否是 与年龄和高血压相关的痴呆的发展。这将为小说的发现奠定基础 恢复脑血流量自动调节以预防和减缓痴呆发病和进展的生物标志物和药物 在老年高血压患者中。

PROJECT SUMMARY/ABSTRACT Hypertension is one of the leading risk factors for cerebrovascular disease and cognitive impairments, especially with aging. Although older hypertensive adults display impaired myogenic response (MR) and autoregulation of cerebral blood flow (CBF), the genes and mechanisms involved and their contribution to hypertension-related dementia are not fully elucidated. This proposal is a direct extension of my R21 application (AG050049) funded by NIA ASG in which we developed animal models to investigate the role of Add3 in mediating cognitive impairments with aging. Our genetic analysis involving the Atherosclerosis Risk in Communities Neurocognitive Study revealed that variants of gamma-adducin (ADD3) are associated with dementia. In animal studies, we genetically mapped a mutation in the Add3 gene in FHH rats that impairs cerebral MR and autoregulation. During the funded R21 period, we generated and characterized Add3 transgenic rats and confirmed that decreased Add3 expression is a driving force for impaired cerebral hemodynamics, which consequently leads to blood-brain barrier (BBB) leakage, inflammation, and ultimately loss of hippocampal neurons and cognitive function upon aging and hypertension. Our new preliminary data demonstrate that downregulation of Add3 damages actin cytoskeletal structure, reduces actin stabilization, and elevates superoxide production in primary cerebral VSMCs isolated from FHH rats. The same structural changes are also observed in glial cells treated with Add3 DsiRNA. In addition, Aβ protein expression in the brain of FHH rats starts to increase as early as 8 weeks of age. There is mitochondrial damage in the brain surrounding leaky capillaries in hypertensive FHH rats. Mitochondrial respiration and ATP production are compromised in glial cells treated with Add3 DsiRNA. Based on this evidence, we HYPOTHESIZE that reduced Add3 expression uncouples F-actin anchoring to the membrane and enhances aberrant actin polymerization, which impairs CBF autoregulation and promotes development of cognitive impairments in aging-hypertension by attenuating cerebrovascular cell constriction, reducing glial Aβ clearance, and exacerbating cerebral vascular mitochondrial dysfunction. We will use Add3 gene KO rat on normal SD genetic background and pharmaceutical interventions to determine if enhanced actin polymerization alters MR of cerebral arteries, which could explain impaired CBF autoregulation, BBB leakage, neurodegeneration, and dementia. We will also determine if there is diminished Aβ clearance and cerebral vascular mitochondrial dysfunction in Add3 KO rats. The results from the proposed studies will establish that aging-hypertension promotes impaired CBF autoregulation, contributing to cognitive deficits. The uncovered mechanisms will address a critical knowledge gap to better understand whether downregulation of ADD3 is a risk factor for development of age- and hypertension-related dementia. This will lay the foundation for discovery of novel biomarkers and drugs that restore CBF autoregulation to prevent the onset and slow the progression of dementia in elderly hypertensive individuals.