The Role and Biology of Fra-1 in Lung Injury and Repair

描述(申请人提供)：转录“激活物”和“抑制物”之间的平衡行为似乎在维持组织动态平衡方面起着关键作用。然而，将平衡转向激活或抑制功能可能会破坏转录(基因表达的最初步骤)，最终导致一种病理状态。事实上，新出现的数据将参与损伤和修复的基因的异常表达与各种环境侮辱联系在一起，这些环境侮辱要么导致或增加了对各种病理状态的易感性，包括急性和慢性肺部疾病。这一竞争性的更新应用专注于扩大我们正在进行的Fra1转录在肺损伤和修复中的新角色的研究。FRA1是AP1(Jun/Fos)的二聚体，AP1受环境胁迫激活，调节正常和病理过程中的基因表达。在上一个资助阶段，我们已经证明了上游启动子元件和血清反应元件之间的相互作用驱动了Fra1的诱导。我们已经证明，异位Fra1在体外促进了肺细胞的运动和侵袭，但它需要其他激活的原癌基因(S)来传递其体内的致癌潜力。尽管新的数据已经明确地证明了Fra1在癌细胞进展和侵袭中的致病作用，但Fra1在非恶性肺部疾病中的确切作用仍不清楚。有趣的是，我们发现，与对照组小鼠相比，Fra1基因的缺失增强了对促氧化剂诱导的肺损伤的保护。我们还发现，FRA1缺乏的细胞比FRA1充足的细胞对促氧化剂诱导的细胞死亡具有更强的抵抗力。在报告分析中，异位的Fra1表达降低了肺上皮细胞中AP1依赖和非依赖的转录反应。基于这些新的初步观察，我们假设Fra1作为“转录抑制因子”发挥作用，从而在促进细胞损伤和肺部发病中发挥关键作用。为了验证我们的假设并进一步分析Fra1启动子的调控，我们提出了以下具体目标：1)利用基因靶向的小鼠和急性肺损伤的实验模型，确定Fra1缺乏对氧化剂暴露的保护作用；2)分析在体外调节基础水平和可诱导的Fra1表达的关键因素；以及3)利用基于tdTomato的非侵入性光学成像技术，在体内和体外检测Fra1在肺部疾病和损伤修复过程中的诱导模式。所提出的研究不仅在阐明FRA1的生物学和功能方面具有新颖性，而且还将为研究促氧化剂诱导的细胞应激和非恶性肺发病的机制基础提供重要的见解。由于细胞应激是许多肺部疾病和恶性肿瘤不可或缺的一部分，这些结果使我们能够将FRA1或专门调节FRA1的步骤作为新的治疗药物(S)。公共卫生相关性：了解Fra1在急性肺损伤中的作用，并描绘Fra1诱导的潜在机制，以及体内基于非侵入性红色荧光的人Fra1启动子激活的光学成像的发展，将有助于我们监控和跟踪宿主对辅助剂和毒物随时间的转录反应，这些细胞正在经历损伤和修复，或与病理/疾病状态相关。本研究的结果将对我们理解MAP激酶/AP1-Fra1信号对应激反应的调控机制，如氧化应激、DNA损伤、炎症等具有重要意义。

DESCRIPTION (provided by applicant): A balancing act between transcriptional "activators" and "repressors" appears to play a key role in maintaining tissue homeostasis. However, shifting the balance in favor of activator or repressor functions can deregulate transcription (the initial step in gene expression), ultimately leading to a pathologic state. Indeed, emerging data have causally linked abnormal expression of genes involved in injury and repair to a wide variety of environmental insults, which either cause or enhance susceptibility to a variety of pathologic states, including acute and chronic lung diseases. This competing renewal application is focused on expanding our ongoing studies of the novel roles of Fra1 transcription in lung injury and repair. Fra1 is a dimeric partner of AP1 (Jun/Fos), which is activated by environmental insults and regulates gene expression that is involved in both normal and pathologic processes. During the last funding period, we have shown that interplay between the upstream promoter elements and the serum response element drives the Fra1 induction. We have shown that ectopic Fra1 promotes lung cell motility and invasion in vitro, but it requires other activated protooncogene(s) to impart its oncogenic potential in vivo. Although emerging data have unequivocally demonstrated a causative role for Fra1 in cancer cell progression and invasion, the exact role of Fra1 in non-malignant lung diseases remains unclear. Intriguingly, we have found that deletion of Fra1 confers increased protection against prooxidant-induced lung injury, when compared to results in control mice. We have also found that Fra1-deficient cells are remarkably more resistant than Fra1-sufficient cells to prooxidant-induced cell death. In reporter assays, ectopic Fra1 expression decreased both AP1-dependent and -independent transcriptional responses in lung epithelial cells. Based on these novel preliminary observations, we hypothesize that Fra1 functions as a "transcriptional repressor," thereby playing a key role in promoting cellular injury and lung pathogenesis. To test our hypothesis and to further to dissect Fra1 promoter regulation, we propose the following specific aims: 1) To determine the mechanisms involved in protection against prooxidant exposure by Fra1 deficiency using gene-targeted mice and experimental models of acute lung injury, 2) to dissect the critical factors that regulate basal-level and inducible Fra1 expression in vitro; and 3) to examine the patterns of Fra1 induction in lung disease and during injury and repair by using tdTomato-based noninvasive optical imaging in vivo and ex vivo. The proposed studies are not only novel in terms of elucidating the biology and functions of Fra1 but will also provide critical insights into the mechanistic basis underlying prooxidant-induced cellular stress and non-malignant lung pathogenesis. Because cellular stress is an integral part of many lung diseases and malignancy, these results could enable us to target Fra1, or steps that specifically regulate Fra1, as novel therapeutic agent(s). PUBLIC HEALTH RELEVANCE: Understanding the role of Fra1 in acute lung injury and delineating the mechanisms underlying FRA1 induction and the development of noninvasive red florescence-based optical imaging of human FRA1 promoter activation in vivo will be helpful in allowing us to monitor and track the host transcriptional response to proxidants and toxicants over time in cells that are undergoing injury and repair or are associated with a pathological/disease state. The results obtained from this study will be of great significance for our understanding of disease mechanisms such as oxidative stress, DNA damage, and inflammation regulated by MAP kinase/AP1-Fra1 signaling in response to stressful stimuli.