The reduction of NLRX1 and its role in pulmonary aging

项目总结 肺系统的生物老化与结构变化有关，这些结构变化导致进行性 功能衰退，而“衰老肺”一词被用来描述处于这一衰退阶段的器官。使用 人口迅速老龄化，深入了解与生理性衰老相关的肺部变化 势在必行。我们最近证明了一种线粒体分子，核苷酸结合域和富含亮氨酸- 线粒体负性调节蛋白X1(NLRX1) 抗病毒信号分子(MAVS)在慢性阻塞性肺疾病发病机制中的作用 疾病(COPD)。由于衰老是慢性阻塞性肺疾病的常见风险因素，因此进行了研究以确定 NLRX1在“肺老化”中发挥着重要作用。我们的初步研究表明：(I)衰老本身导致了 NLRX1在小鼠肺组织中基因和蛋白水平的降低；(Ii)主要降低的部位是在 巨噬细胞；和(Iii)12月龄(Mo)NLRX1缺失突变(-/-)小鼠的肺表现出增强 具有“肺衰”的特点。在NLRX1-/-小鼠身上观察到的这些特征包括：(A)激活 炎症体，(B)增加p53信号及其靶分子早幼粒细胞白血病(PML；一种众所周知的 细胞衰老的标志)，(C)减少血管内皮生长因子(VEGF)的产生，这是一个关键 肺血管调节因子和细胞保护及(D)老年肺气肿样肺泡的增强 重塑，所有这些都在野生型(WT)对照组的肺中被适度观察到。此外，我们 发现NLRX1作为与PTEN诱导的激酶1相互作用的分子具有前所未有的功能 (PINK1)，线粒体质量控制的重要调节因子。NLRX1在衰老研究中的重要性是 在人类中很明显，显示NLRX1在外周血中的表达显著减少 老年人(65岁)的单个核细胞与年轻对照组(40岁)的比较。这 一系列的发现使我们假设，衰老导致的NLRX1的减少起着关键作用 在肺系统衰老中，至少通过线粒体功能障碍/分子失调来实现。至 验证这一假设，我们将利用NLRX1基因可以零突变或 分别以时间空间的方式诱导。由特定假设驱动的建议目标是：目标1。 明确NLRX1的变化及其在体内肺衰老中的作用(S)；目的#2.确定是否恢复 NLRX1在体内的表达可减轻肺系统中与衰老相关的改变；目标#3。 描述衰老时肺中线粒体功能障碍/分子失调的特征，并确定其作用 NLRX1在衰老相关线粒体功能障碍/分子失调中的作用据我们所知， NLRX1是一种天然免疫调节剂，在衰老的背景下从未被研究过。它的具体职能(S)在 巨噬细胞，尽管这种细胞类型对正常衰老的组织动态平衡很重要，但从未 也被定义了。拟议的AIMS将探讨这些前所未有的问题。

PROJECT SUMMARY Biological aging of the pulmonary system is associated with structural changes that lead to a progressive decline in function, and the term “aging lung” is used to describe the organ in this stage of decline. With population rapidly aging, a thorough understanding of physiologic aging-related changes in the lung is imperative. We recently demonstrated a mitochondrial molecule, nucleotide-binding domain and leucine-rich- repeat-containing protein X1 (NLRX1) which has been identified as a negative regulator of mitochondrial antiviral signaling molecule (MAVS), plays a critical role in the pathogenesis of chronic obstructive pulmonary disease (COPD). Because aging is a common risk factor for COPD, studies were undertaken to determine if NLRX1 is an important player in “aging lung.” Our preliminary studies revealed that (i) aging itself induced the reduction of NLRX1 at the level of gene and protein in murine lungs; (ii) the site of major reduction was in macrophages; and (iii) the lungs from 12-month-old (mo) NLRX1 null mutant (-/-) mice manifested enhanced characteristics of the “aging lung.” These features observed from NLRX1-/- mice included (a) activation of the inflammasome, (b) increased p53 signaling and its target molecule promyelocytic leukemia (PML; a well-known marker of cellular senescence), (c) decreased production of vascular endothelial growth factor (VEGF), a key regulator of pulmonary vasculature and cytoprotection and (d) enhancement of senile emphysema-like alveolar remodeling, all of which were modestly observed in lungs from wild type (WT) controls. In addition, we identified an unprecedented function of NLRX1 as an interacting molecule with PTEN-induced kinase 1 (PINK1), an essential regulator of mitochondrial quality control. The importance of NLRX1 in aging studies was evident in humans, revealing the expression of NLRX1 was significantly reduced in peripheral blood mononuclear cells from the elderly (age>65) compared to those from young controls (age<40). This constellation of findings led us to hypothesize that aging-induced reduction of NLRX1 plays a critical role in the aging of pulmonary system via, at least, mitochondrial dysfunction/molecular dysregulation. To test the hypothesis, we will utilize newly generated mice in which the NLRX1 gene can be null mutated or induced, respectively, in a temporospatial manner. Proposed aims driven by specific hypotheses are: Aim #1. Define the alteration of NLRX1 and its role(s) in pulmonary aging in vivo; Aim #2. Determine if restoring the expression of NLRX1 in vivo attenuates aging-related alterations in the pulmonary system; Aim #3. Characterize the mitochondrial dysfunction/molecular dysregulation in the lung with aging and define the role that NLRX1 plays in aging-related mitochondrial dysfunction/molecular dysregulation. To our best knowledge, NLRX1, an innate immune regulator, has never been studied in the context of aging. Its specific function(s) in macrophages, in spite of the importance of this cell type for tissue homeostasis with normal aging, have never been defined, either. The proposed aims will explore these unprecedented issues.