The reduction of NLRX1 and its role in pulmonary aging

项目摘要 肺系统的生物老化与导致进行性肺损伤的结构变化有关。 功能衰退，术语“老化肺”用于描述处于此衰退阶段的器官。与 随着人口的迅速老龄化，对肺的生理老化相关变化的深入了解是 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的- 含重复序列的蛋白X1（NLRX 1）已被确定为线粒体的负调节因子， 抗病毒信号分子（MAVS）在慢性阻塞性肺疾病的发病机制中起着重要作用 疾病（COPD）。由于衰老是COPD的常见风险因素，因此进行了研究以确定 NLRX 1是“肺老化”的重要参与者。我们的初步研究表明，（i）衰老本身诱导了 在小鼠肺中NLRX 1在基因和蛋白水平上的减少;（ii）主要减少的位点在 （iii）来自12个月大（mo）NLRX 1无效突变（-/-）小鼠的肺表现出增强的 “肺老化”的特征。从NLRX 1-/-小鼠中观察到的这些特征包括：（a）激活NLRX 1-/-小鼠中的 炎性小体，（B）增加p53信号传导及其靶分子早幼粒细胞白血病（PML;一种众所周知的 细胞衰老的标志物），（c）减少血管内皮生长因子（VEGF）的产生， 调节肺血管和细胞保护和（d）增强老年肺气肿样肺泡 重构，所有这些在野生型（WT）对照的肺中适度观察到。另外我们 鉴定了NLRX 1作为与PTEN诱导的激酶1相互作用的分子的前所未有的功能 （PINK 1），线粒体质量控制的重要调节剂。NLRX 1在衰老研究中的重要性是 在人类中是明显的，揭示了NLRX 1的表达在外周血中显著降低 来自老年人（年龄>65）的单核细胞与来自年轻对照（年龄<40）的单核细胞相比。这 一系列的研究结果使我们假设，衰老诱导的NLRX 1减少在 至少通过线粒体功能障碍/分子失调导致肺系统老化。到 为了验证这一假设，我们将利用新产生的小鼠，其中NLRX 1基因可以是无效突变的，或者 分别以时空的方式诱导。由特定假设驱动的拟议目标是：目标#1。 定义NLRX 1的改变及其在体内肺老化中的作用;目的#2。确定是否恢复 NLRX 1在体内的表达减弱了肺系统中与衰老相关的改变;目的#3。 描述肺中线粒体功能障碍/分子失调与衰老的关系，并确定其作用 NLRX 1在衰老相关的线粒体功能障碍/分子失调中发挥作用。据我们所知， NLRX 1是一种先天免疫调节因子，从未在衰老的背景下进行过研究。其具体职能是 巨噬细胞，尽管这种细胞类型对正常衰老的组织稳态很重要，但从未 也被定义了。拟议的目标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.