Role of SIRT1 in vasoprotection

描述(由申请人提供)：氧化应激在衰老过程中的血管损伤中起着关键作用。本提案的目标是确定新的机制，作为血管氧化还原动态平衡的调节者，从而抑制氧化应激诱导的衰老炎症过程。先前的研究表明，卡路里限制(CR)可以减缓与年龄相关的氧化应激增加，并延长寿命。重要的是，CR的年龄相关效应似乎依赖于NAD+依赖的蛋白去乙酰基酶SIRT1。SIRT1在血管系统中表达，调节多方面的血管保护途径。在拟议的研究中，我们假设由CR或该酶的药理激活剂诱导的SIRT1依赖通路在衰老过程中传递血管保护作用。核因子-E2相关因子2(NRF2)是一种转录因子，调节多种ROS解毒和抗氧化基因的表达。我们最近证明，限制热量摄入对小鼠肿瘤的发生具有保护作用，这是通过上调Nrf2来实现的。我们的初步数据表明，Nrf2在CR在衰老过程中的血管保护中起着类似的作用。Nrf2/ARE途径的一个主要下游效应因子是依赖NAD(P)H：Quone氧化还原酶(NQO1)的跨质膜抗氧化剂氧化还原系统。尽管NQO1被CR上调，但其对内皮细胞氧化应激的保护作用是完全未知的。该项目的总体目标是验证这样的假设，即热量限制通过激活SIRT1和诱导Nrf2调节的ROS解毒系统(包括NQO1)来保护血管系统免受与衰老相关的氧化应激的有害影响。我们假设，在内皮细胞中这一通路的药理激活模拟了热量限制的效果，这对衰老期间的血管保护具有重要的干预策略。1/a：确定热量限制是否通过激活SIRT1，通过减轻线粒体氧化应激和抑制血管炎症，对衰老动物起到血管保护作用。1/b：确定SIRT1的药理激活剂对年龄相关性血管损伤的治疗效果。2/a：确定Nrf2/ARE通路的诱导是否介导了卡路里限制在衰老中的血管保护作用。2/b：确定NQO1依赖的跨质膜抗氧化剂氧化还原系统的上调是否在衰老过程中提供血管保护。拟议的研究将首次对热量限制有助于防止与年龄相关的血管功能下降的影响和潜在机制进行全面分析。这些实验将为SIRT1和Nrf2/ARE通路在生物衰老过程中的作用提供新的和明确的信息，并将解决与抗氧化系统在心血管功能的发生和调节以及与年龄相关的病理学中的作用相关的重大争议。

DESCRIPTION (provided by applicant): Oxidative stress plays a key role in vascular impairment during aging. The goal of the present proposal is to identify novel mechanisms that act as regulators of vascular redox homeostasis and thus suppress oxidative stress-induced inflammatory processes in aging. Previous studies indicate that caloric restriction (CR) attenuates the age- related increase in oxidative stress and increases lifespan. Importantly, the age-related effects of CR appear to be dependent on the NAD+ dependent protein deacetylase SIRT1. SIRT1 is expressed in the vasculature and regulates multifaceted vasoprotective pathways. In the proposed studies, we hypothesize that induction of SIRT1- dependent pathways by CR or by pharmacological activators of the enzyme conveys vasoprotective effects in aging. NF-E2-related factor 2 (Nrf2) is a transcription factor, that regulates the expression of numerous ROS detoxifying and antioxidant genes. We have recently demonstrated that caloric restriction exhibits a protective action against tumorigenesis in mice by upregulation of Nrf2. Our preliminary data suggest that Nrf2 plays a similar role in vasoprotection by CR in aging. A major downstream effector of the Nrf2/ARE pathway is the NAD(P)H:quinone oxidoreductase (NQO1) -dependent trans-plasma membrane antioxidant redox system. Although NQO1 is up-regulated by CR, its protection against oxidative stress in endothelial cells is completely unknown. The overall goal of the proposed project is to test the hypothesis that caloric restriction protects the vasculature from the deleterious effects of oxidative stress associated with aging, via activation of SIRT1 and induction of the Nrf2- regulated ROS detoxification systems (including NQO1). We posit that pharmacological activation of this pathway in endothelial cells mimics the effects of caloric restriction, which contributes significantly to an intervention strategy for vasoprotection during aging. The following aims are proposed: 1/a: Determine whether caloric restriction, via activating SIRT1, exerts vasoprotective effects in aging animals by attenuating mitochondrial oxidative stress and inhibiting vascular inflammation. 1/b: Define the efficacy of treatment with pharmacological activators of SIRT1 on age-related vascular impairment. 2/a: Determine whether induction of the Nrf2/ARE pathway mediates the vasoprotective effects of caloric restriction in aging. 2/b: Determine whether up-regulation of the NQO1-dependent trans-plasma membrane antioxidant redox system confers vasoprotection in aging. The proposed studies will provide the first comprehensive analysis on the effects and potential mechanisms through which caloric restriction contributes to preventing the age-related decline in vascular function. These experiments will provide novel and definitive information on the actions of SIRT1 and the Nrf2/ARE pathway during biological aging and will resolve significant controversies related to the effects of antioxidant systems on the genesis and modulation of cardiovascular function and age- related pathology.