Regulation and function of EC-SOD

描述（申请人提供）：细胞外超氧化物歧化酶（EC-SOD）是肺中最丰富的细胞外抗氧化酶，目前的研究表明，EC-SOD在氧化诱导的肺和血管损伤及其炎症的发病机制中起关键作用。我们和其他人已经证明，小鼠肺中EC-SOD的过表达可以保护肺免受高氧暴露、残油飞灰、流感肺炎、出血性肺损伤、放射性肺炎、博莱霉素诱导的肺纤维化等急性肺损伤，并在新生儿高氧模型中保护肺发育。在心血管疾病模型中，EC-SOD可以预防缺血再灌注损伤，减轻高血压，而特异性多态性会显著增加缺血性心脏病的风险。尽管有这项工作，EC-SOD在这些疾病过程中的保护作用的确切机制仍不清楚。最近，我们已经开始揭示调节EC-SOD组织和细胞特异性表达的重要因素。在这一竞争性更新应用中，我们将以我们最近的发现为基础，开始探索控制EC-SOD基因表达的分子途径。基于我们对人和小鼠EC-SOD基因的初步表征，我们现在假设EC-SOD的转录表达受一系列转录因子（Ets、MZF-1、Kruppel和Sp1/Sp3）的调控，这些转录因子与位于小鼠EC-SOD基因5'-非翻译区近端和远端启动子元件相互作用。进一步提出，这些元件的活性是由表观遗传过程，包括组蛋白乙酰化和甲基化调节。为了验证这些假设，我们提出了3个具体目标。目的1将检查顺式元件和反式激活因子在肺中调节基础和细胞特异性EC-SOD表达的贡献和鉴定。在目标2中，我们将识别和表征负责调节EC-SOD基因转录的转录因子元件。在Aim 3中，将使用一种新的体内生物发光成像系统，利用新发现的EC-SOD近端和远端启动子元件，在转基因小鼠中检测功能和空间基因表达谱。预计这项工作将为我们对EC-SOD基因表达调控的分子机制的理解提供新的见解。这可能会导致新的药理学策略，以增加肺部和其他组织中的内源性EC-SOD水平，这将减少细胞外氧化应激和减轻肺部疾病的进程。

DESCRIPTION (provided by applicant): Extracellular superoxide dismutase (EC-SOD) is the most abundant extracellular antioxidant enzyme in the lung and current studies indicates that EC-SOD plays a key role in the pathogenesis of oxidant-induced pulmonary and vascular injury and resulting inflammation. We and others have shown that EC-SOD overexpression in the lungs of mice protects the lungs against acute lung injury from hyperoxia exposure, residual oil fly ash, influenza pneumonia, hemorrhage induced lung injury, radiation pneumonitis, bleomycin-induced lung fibrosis and preserves lung development in a neonatal model of hyperoxia. In cardiovascular disease models, EC-SOD protects against ischemia-reperfusion injury, attenuates hypertension, and specific polymorphisms impart a significant increased risk for ischemic heart disease. Despite this work, the precise mechanism of EC-SOD's protective role in these disease processes remains unclear. Recently we have begun to unravel factors important in regulating EC-SOD tissue and cell-specific expression. In this competing renewal application, we will build on our most recent findings that have begun to explore molecular pathways that control EC-SOD gene expression. Based on our initial characterization of the human and mouse EC-SOD genes, we now hypothesize that EC-SOD transcriptional expression is regulated by a family of transcription factors (Ets, MZF-1, Kruppel, and Sp1/Sp3) interacting at a proximal and distal promoter element located in the 5'-untranslated region of the murine EC-SOD gene. It is further proposed that the activity of these elements is modulated by epigenetic processes including histone acetylation and methylation. To test these hypotheses, we propose 3 specific aims. Aim 1 will examine the contribution and identification of cis-elements and trans-activating factors regulating basal and cell specific EC-SOD expression in the lung. In Aim 2, we will identify and characterize transcription factor elements responsible for modulation of EC-SOD gene transcription. In Aim 3 will use a novel in vivo bioluminescence imaging system to examine the functional and spatial gene expression profile utilizing the newly discovered EC-SOD proximal and distal promoter elements in transgenic mice. It is anticipated that this work will provide new insights into our understanding of molecular mechanisms involved in the regulation of EC-SOD gene expression. This could lead to novel pharmacologic strategies for augmenting endogenous EC-SOD levels in the lungs and other tissues, which would be predicted to reduce extracellular oxidative stress and attenuate lung disease processes.