Regulation of Antioxidant Genes and Oxidative Stress

说明(申请人提供)：铁是一种必需元素，因为它是参与多种细胞功能的重要细胞蛋白的组成部分；然而，过量的铁是有害的，因为它催化形成活性氧物种(ROS)。铁缺乏或铁负荷过多引起的铁稳态紊乱与神经退行性疾病、癌症和衰老等多种人类健康问题有关。因此，微调细胞内的铁水平对于维持正常的细胞功能和生理代谢平衡是必不可少的。铁蛋白是真核细胞中主要的铁储存蛋白，它通过解毒和以无毒但可生物利用的形式储存细胞内多余的铁，在调节铁代谢方面发挥着至关重要的作用。铁蛋白的合成在转录和翻译水平上都受到调控。铁对铁蛋白的翻译调控机制已经得到了广泛的研究和很好的描述。相比之下，在细胞需要限制铁供应的情况下，铁蛋白基因的铁非依赖性转录调控仍然不完全清楚。特别是，氧化应激条件下通过染色质重塑机制对铁蛋白的转录调控知之甚少。铁蛋白和一系列抗氧化基因的转录受一个保守的增强子调控，该增强子被称为ARE(抗氧化反应元件)。我们推测，我们最近在人类铁蛋白上确定的染色质重塑和相关因子可以作为调节铁蛋白转录和铁稳态的关键蛋白。拟议的实验将集中于这些新的ARE相互作用蛋白的特征及其在染色质修饰中的作用，这些染色质修饰邻近ARE调节的铁蛋白和抗氧化基因。这项研究的科学影响将是广泛和重大的，因为它不仅将通过对转录因子和染色质重塑因子的协调调节，为一组抗氧化基因的基本转录机制提供新的见解，而且还将定义新的调控蛋白，负责细胞抗氧化反应和与各种与铁和ROS相关的人类疾病相关的氧化应激条件下的铁稳态。

DESCRIPTION (provided by applicant): Iron is an essential element by serving as a constituent of vital cellular proteins involved in a variety of cellular functions; however, excess iron is detrimental because it catalyzes formation of reactive oxygen species (ROS). Disorder of iron homeostasis involving iron deficiency or overload is associated with various human health problems such as neurodegenerative disease, cancer and aging. Fine-tuning of intracellular iron levels is therefore essential for maintaining normal cellular function and physiological metabolic balance. Ferritin is the major iron-storage protein in eukaryotic cells and it plays a crucial role in regulation of iron metabolism by detoxifying and storing intracellular excess iron in a non-toxic but bioavailable form. Ferritin synthesis is regulated at both transcriptional and translational levels. Translational regulatory mechanism of ferritin by iron has been extensively studied and well characterized. In contrast, iron-independent transcriptional regulation of the ferritin gene under such conditions as cells need to limit iron availability remains incompletely understood. In particular, little is known about ferritin transcriptional regulation through chromatin remodeling mechanism under oxidative stress conditions. Transcription of ferritin and a battery of antioxidant genes are regulated by a conserved enhancer, termed the ARE (antioxidant responsive element). We hypothesize that chromatin remodeling and associated factors we have recently identified on the human ferritin ARE can serve as crucial proteins that regulate ferritin transcription and iron homeostasis. The proposed experiments will focus on characterization of these new ARE-interacting proteins and their roles in chromatin modifications adjacent to ARE-regulated ferritin and antioxidant genes. The scientific impact of this research will be broad and significant because it will not only provide new insight into the basic transcriptional mechanism of a group of antioxidant genes via coordinated regulation of transcription factors and chromatin-remodeling factors, but also define new regulatory proteins responsible for cellular antioxidant response and iron homeostasis under oxidative stress conditions that are associated with various iron- and ROS-involving human diseases.