Peroxiredoxin 6 and Cataractogenesis

描述（由申请人提供）：最近的证据表明氧化应激在老年性白内障的病因中起作用，并且表明衰老的晶状体细胞由于抗氧化剂的表达减少而容易受到这种损伤。由于晶状体持续暴露于环境胁迫下，不断产生活性氧（ROS），如果不去除，细胞微环境中活性氧的形成和局部积累增加，通过启动广谱有害信号导致晶状体细胞损伤，如果这种情况持续下去，可能导致白内障发生。过氧化氧还蛋白6 （PRDX6）是一种同时具有GSH过氧化物酶和aiPLA2（酸性Ca2+独立磷脂酶A2）活性的“月光蛋白”，在晶状体中高度表达。我们的研究表明，随着年龄的增长，晶状体细胞中PRDX6的表达减少，细胞内ROS水平升高。通过在小鼠中靶向灭活Prdx6基因，我们发现Prdx6缺失的晶状体和/或晶状体上皮细胞（LECs）含有较高水平的ROS和生物活性tgf21；TGF21诱导基因如1- sm -肌动蛋白和2ig-h3的过度调节导致表型改变，这些基因与白内障发生的病理生理有关。我们设想了一个恶性前馈过程（ROS??）TGF 1 ? ?ROS =基因的过度调节)发生在老化的LECs或面临氧化应激的LECs的局部微环境中，因此，我们假设通过阻断ROS介导的有害信号，通过中断细胞微环境中局部高水平的ROS和激活的TGF21引发的恶性循环，可以减少白内障发生的进展。我们认为这些事件是因果相关的，即环境应激和年龄相关的晶状体组织中PRDX6的减少导致ros诱导的膜或胞质因子损伤，由于这种损伤，细胞稳态系统失效。因此，本课题的总体目标是揭示氧化应激在白内障形成的病理生理学中的作用，并通过三个具体目标显示PRDX6治疗/延缓白内障发生的能力：1)了解PRDX6的功能意义及其在氧化应激和衰老过程中的调节作用。2)利用TAT-HA- PRDX6在PRDX6 -/-缺失小鼠、百草枯诱导氧化应激小鼠和舒米亚白内障大鼠（SCR）中转运PRDX6蛋白，评估PRDX6在体外和体内对氧化应激细胞的保护作用，并评估PRDX6是否减缓白内障进展。3)研究PRDX6在氧化应激下正常、老化LECs和细胞中的调控机制，明确下游氧化还原信号在调控其基因转录中的作用。这些研究将为氧化应激在白内障形成中的作用提供新的见解，并将为合理使用基于抗氧化的治疗方法来治疗或预防/延迟白内障的发生提供基础。老年性白内障是一种常见的眼部疾病，是导致失明的主要原因之一。尽管有证据表明活性氧驱动的氧化应激在包括ARC在内的年龄相关退行性疾病的进展和病因学中发挥作用，但氧化应激诱导的有害信号传导机制（导致疾病状态的细胞损伤原因）尚不清楚。因此，抗氧化治疗或联合治疗的临床应用充其量是模棱两可的。利用晶状体作为年龄相关疾病的模型，我们将揭示氧化应激或衰老过程中组织/器官病理生理的潜在机制。建议的研究将为开发以抗氧化剂为基础的治疗或治疗组合提供可靠的科学基础，以预防白内障的发生和一般的年龄相关的退行性疾病。

DESCRIPTION (provided by applicant): Recent evidence implicates that the oxidative stress plays a role in the etiology of Age-Related Cataract, and suggests that aged lens cells are prone to this damage due to reduced expression of antioxidants. Because ocular lens is constantly exposed to environmental stress, it continuously generates reactive oxygen species (ROS), if not removed, increased formation and local accumulation of ROS in the cellular microenvironment causes lens cell damage-by initiating wide-spectrum of deleterious signaling and if this situation prolongs may lead to cataractogenesis. Peroxiredoxin 6 (PRDX6), a 'moonlighting protein' with both GSH peroxidase and aiPLA2 (acidic Ca2+independent phospholipase A2) activities, is highly expressed in lens. Our studies have shown diminution of PRDX6 expression and higher intracellular ROS levels in lens cells during aging. Using targeted inactivation of Prdx6 gene in mice, we found that Prdx6-depleted lenses and/or lens epithelial cells (LECs) contain elevated levels of ROS and bio-activeTGF21; exhibit phenotypic changes with overmodulation of TGF21 inducible genes such as 1-SM-actin and 2ig-h3, and these genes are implicated in pathophysiology of cataractogenesis. We envisage a vicious feed-forward-process (ROS?? TGF?1??ROS = overmodulation of genes??) taking place within the local microenvironment of aging LECs or LECs facing oxidative stress, and therefore, we hypothesized that by blocking ROS mediated deleterious signaling should reduce progression of cataractogenesis, by interrupting the vicious cycle initiated by locally high levels of ROS and activated TGF21 within cellular microenvironment. We believe that these events are causally related, i.e., that the environmental stress and age-related reduction in PRDX6 in lens tissues leads to ROS-induced damage of membrane or cytosolic factors, as a consequence of this damage, cell homeostatic system fails. The over all goal of this proposal, therefore, is to unveil the roles of oxidative stress in pathophisiology of cataract formation and to show PRDX6 ability in treating/delaying cataractogenesis through three specific aims: 1) Understand the functional significance of PRDX6 and its regulatory role during oxidative stress and aging. 2) Assess the antioxidant potential of PRDX6 in protecting cells facing oxidative stress in vitro and in vivo using TAT-HA- PRDX6 to cargoing PRDX6 protein in Prdx6-/- depleted mice and mice with Paraquat-induced oxidative stress as well as Shumiya cataract rat (SCR), and assess whether cataract progression is slowed by PRDX6. 3) Investigate the regulatory mechanisms of PRDX6 in normal and aging LECs and cells under oxidative stress and define role(s) of downstream redox signaling in controlling its gene transcription. These studies should provide novel insights into the role of oxidative stress in cataract formation and will provide a foundation for rational use of antioxidant based therapeutics for treating or preventing/delaying cataractogenesis. A common disorder of the eye, Age-Related Cataract (ARC) is among the leading causes of blindness. Although evidence suggests a role for reactive oxygen species-driven oxidative stress in the progression and etiology of age-related degenerative diseases including ARC, the mechanism of oxidative stress-induced deleterious signaling, a cause of cellular damage that leads to the disease state, is not clear. Thus clinical application of antioxidant therapy or combination of therapies has been at best equivocal. Using eye lens as a model for age-associated disorders, we will unveil the underlying mechanism involved in the pathophysiology of tissues/organs during oxidative stress or aging. The proposed studies will provide a sound scientific basis for developing an antioxidant-based therapy or combination of therapies for preventing cataractogenesis and age-associated degenerative diseases in general.