Reactive Oxygen Species and Telomeres in Cardiovascular Disease

描述(申请人提供)：动脉粥样硬化和由此导致的心血管疾病(CVD)是美利坚合众国死亡的主要原因，每三例死亡中就有一例可归因于CVD。风险因素，如老龄化、肥胖、吸烟和高血压已被确定，但动脉粥样硬化的原因仍不清楚。活性氧簇(ROS)的产生增加和端粒功能障碍与动脉粥样硬化的发展有关。ROS被认为是心血管疾病的重要因素，动脉粥样硬化斑块中端粒缩短的发生率增加。此外，白细胞中端粒的缩短与心血管疾病的易感性增加有关。最近发表的报告确认ROS是TERT的调节者，TERT是端粒酶的催化亚单位，它利用其酶活性来维持端粒长度。新发现的ROS和TERT之间的关系表明，它们在心血管疾病中的作用是相互关联的。然而，ROS与CVD进展中端粒维持之间的关系尚不清楚，目前尚不清楚这种关系是因果关系还是相关关系。我推测ROS促进动脉粥样硬化的作用部分是ROS作用于端粒功能的结果。在这里，我建议进行一系列研究，以确定氧化应激增加对端粒维持的影响。在这项建议中，我将利用从单倍体缺陷超氧化物歧化酶2(SOD2)小鼠分离的主动脉平滑肌细胞(SMCs)，这是一种用于研究ROS对动脉粥样硬化的作用的已建立的模型。SOD2小鼠的这种创新使用使我能够直接评估动脉粥样硬化模型中的端粒和端粒酶状态。对于目标1，我将确定ROS对端粒酶活性的影响以及ROS调节端粒酶的机制。初步数据显示，与野生型(WT)SMC相比，SOD2 SMC的端粒酶活性约低50%，证实了氧化应激增加会降低端粒酶活性。在目标2中，我将通过测量端粒长度和端粒完整性来确定ROS对端粒的影响。在目标3中，我将确定抗动脉粥样硬化剂雌激素和维生素E是否能逆转端粒维持中依赖ROS的缺陷。这些研究的结果将为理解体内ROS对TERT的调控(Aim 1)提供基础，提供ROS对端粒影响的直接评估(Aim 2)，并确定端粒维持是否是抗动脉粥样硬化剂(Aim3)的靶点。总之，这项研究的完成将阐明ROS与CVD机制中端粒维持之间的直接联系，从而进一步推动我们对动脉粥样硬化的分子基础形成准确和完整的了解。增加对心血管疾病分子机制的了解将改进治疗、预防和诊断心血管疾病的策略。

DESCRIPTION (provided by applicant): Atherosclerosis and the resulting cardiovascular disease (CVD) are the leading cause of mortality in the United States of America where one in every three deaths is attributed to CVD. Risk factors such as ageing, obesity, smoking and hypertension have been identified but the cause of the atherosclerosis is still unknown. Increased production of reactive oxygen species (ROS) and telomere dysfunction has been implicated in the development of atherosclerosis. ROS is considered a significant contributor to CVD and there is increased occurrence of shorten telomeres in atherosclerotic plaques. Additionally, shortened telomeres in leucocytes are associated with increased pre-disposition of CVD. Recently published reports have identified ROS as a regulator of TERT, the catalytic subunit of telomerase, which uses its enzymatic activity to maintain telomere length. The newly discovered relationship between ROS and TERT suggests that their roles in CVD are interconnected. However, the relationship between ROS and telomere maintenance in CVD progression is poorly understood, and it is not clear whether the relationship is causative or correlative. I hypothesize that the pro-atherosclerotic effects of ROS are in part the result of ROS action on telomere function. Here, I propose a series of studies to determine the effects of increased oxidative stress on telomere maintenance. For this proposal, I will utilize the aortic smooth muscle cells (SMCs) isolated from haplodeficient superoxide dismutase 2 (SOD2 ) mice, an established model used to study ROS contribution to atherosclerosis. This innovative use of SOD2 mouse allows me to directly assess telomere and telomerase status in an atherosclerotic model. For Aim 1, I will determine ROS effect on telomerase activity and the mechanisms of ROS regulation of telomerase. Preliminary data shows that telomerase activity is approximately 50% less in SOD2 SMCs compared to wild type (WT) SMCs confirming that increased oxidative stress decreases telomerase activity. In Aim 2, I will determine the effects of ROS on telomeres by measuring telomere lengths and telomere integrity. In Aim 3, I will determine if the anti-atherosclerotic agents estrogen and vitamin E reverse ROS-dependent deficits in telomere maintenance. The results from these studies will provide the basis for understanding ROS regulation of TERT in vivo (Aim 1), provide a direct assessment of the effects of ROS on telomeres (Aim 2) and determine if telomere maintenance is a target of anti-atherosclerotic agents (Aim3). Overall, the completion of the proposed research will elucidate a direct connection between ROS and telomere maintenance in CVD mechanism furthering our goal to form an accurate and complete understanding of the molecular basis of atherosclerosis. Increased understanding of CVD molecular mechanisms will improve strategies towards the treatment, prevention and diagnosis of CVD.