Nrf2 signaling and oxidative stress in Age-related macular degeneration

描述（由申请人提供）：在美国，年龄相关性黄斑变性（AMD）是获得性失明的主要原因。早期疾病患者的预防和治疗选择有限且无效。为了解决这一缺陷，本建议侧重于早期疾病的机制。吸烟是与AMD最强的流行病学联系，但我们还不完全了解其在该病病理生理中的作用。香烟烟雾是一种强大的化学氧化剂，也是补体激活的有效诱导剂。这两个因素都被认为是AMD发展的重要因素。AMD的一个关键早期事件是视网膜色素上皮细胞（RPE）的凋亡，部分原因是氧化应激不充分。核因子-红细胞2相关因子2 （Nrf2）是一种碱性亮氨酸拉链氧化还原敏感转录因子，通过结合被称为抗氧化反应元件的顺式作用增强子序列来调节抗氧化和细胞保护基因的诱导表达。正常情况下，Nrf2水平较低，但在氧化刺激下，Nrf2从其细胞质抑制剂Keap1中释放出来后，核积累增加，并激活其下游抗氧化酶的协调转录。Nrf2信号的减少在衰老和疾病中可见，导致适应性应激反应不足。有趣的是，Nrf2活性的下降可以通过合成齐墩果酸的三萜衍生物来逆转，齐墩果酸代表了一种有前途的新型细胞氧化损伤保护剂。在本研究中，我们假设慢性吸烟诱导眼底持续氧化应激，并且随着AMD的发病，局部Nrf2信号变得不足。最近，我们发现慢性香烟烟雾可引起小鼠RPE的氧化和超微结构损伤，并最终导致细胞凋亡。我们将利用这一系统利用转基因小鼠来验证我们的假设，目的如下：1)验证Nrf2信号可以防止香烟引起的眼底氧化应激和细胞凋亡的假设。2)探讨Nrf2信号对补体激活的调控是否决定了吸烟对眼底的损伤和凋亡。3)确定Nrf2的药理激活剂是否能保护眼底免受氧化损伤和补体激活。

DESCRIPTION (provided by applicant): Age-related macular degeneration (AMD) is the leading cause of acquired blindness in the United States. Patients with early disease suffer from limited and ineffective options for prevention and treatment. To address this shortcoming, this proposal focuses on the mechanisms underlying early disease. Cigarette smoking is the strongest epidemiological link with AMD, yet we do not fully understand its role in the pathophysiology of this disease. Cigarette smoke is a powerful chemical oxidant, and a potent inducer of complement activation. Both of these factors are thought to be important in AMD development. A key early event in AMD is apoptosis of the retinal pigmented epithelium (RPE), in part through inadequately neutralized oxidative stress. Nuclear factor- erythroid 2-related factor 2 (Nrf2), a basic leucine zipper redox-sensitive transcription factor, regulates the inducible expression of antioxidant and cytoprotective genes by binding to the cis-acting enhancer sequence known as the antioxidant response element. Normally, Nrf2 levels are low, but with an oxidative stimulus, nuclear accumulation of Nrf2 increases after it is released from its cytoplasmic inhibitor Keap1, and activates the coordinated transcription of its downstream antioxidant enzymes. Decreased Nrf2 signaling is seen in aging and disease, resulting in an inadequate adaptive stress response. Intriguingly, the decreased Nrf2 activity can be reversed by the synthetic triterpenoid derivatives of oleonolic acid, which represent a promising new class of agents for cytoprotection from oxidative injury. In this proposal, we hypothesize that chronic cigarette smoking induces persistent oxidative stress in the fundus, and that local Nrf2 signaling becomes inadequate with the onset of AMD. Recently, we showed that chronic cigarette smoke induces oxidative and ultrastructural damage, and eventually apoptosis to the RPE of mice. We will exploit this system using genetically modified mice to address our hypothesis with the following aims: 1) To test the hypothesis that Nrf2 signaling protects against cigarette smoke-induced oxidative stress and apoptosis in the fundus. 2) To investigate the hypothesis that regulation by Nrf2 signaling on complement activation determines the damage and apoptosis to the fundus that is induced by cigarette smoke. 3) To determine if a pharmacological activator of Nrf2 protects the fundus from oxidative damage and complement activation. PUBLIC HEALTH RELEVANCE: Age-related macular degeneration is now the most common cause of blindness among the elderly in the United States, yet our understanding of how early disease develops is limited. Cigarette smoking is the strongest risk factor associated with AMD yet we do not understand how it causes disease onset or progression. This proposal will study how cigarette smoking triggers the onset of macular degeneration. Experiments will explore if Nuclear factor-erythroid 2-related factor 2 (Nrf2), a transcription factor that activates antioxidant and cytoprotective enzymes, protects against cigarette smoke induced oxidative stress and complement activation. This proposal will also explore whether triterpenoids, or small molecules that can activate Nrf2, will prevent the development of AMD in mouse models.