Role of proinflammatory tRNA-derived RNAs in asthma

项目概要和摘要 哮喘是一种慢性炎症性疾病，其特征是炎症、粘液产生、气道炎症、呼吸道 重塑和高反应性导致严重的支气管收缩。这些过程 涉及驻留气道细胞和浸润的炎症细胞之间的相互作用。过敏性炎症 介质如细胞因子、趋化因子和生长因子作用于驻留的气道细胞， 气道平滑肌（ASM）导致结构和功能变化。然而，知识差距 我们对炎症介质的分子因素和机制的理解仍然存在 调节ASM表型。炎症介质改变基因表达，并有助于 哮喘的发病机制。在常驻气道细胞中基因表达的转录调节已经被研究， 广泛研究。然而，靶细胞中的蛋白质功能可以在多个水平上调节， 从转录开始，然后是转录后、翻译和翻译后步骤。在这一背景下， 小的非编码RNA（ncRNA），包括来自转移RNA（tRNA）的那些已经进化 作为转录后基因表达的关键调节因子之一。 我们认为，tRNA的一半，一个主要的tRNA衍生的ncRNA亚群，发挥重要作用， 哮喘病理生物学，并可作为哮喘治疗的靶点。在初步研究中，我们发现， 小鼠肺表达特异性tRNA半种，其水平在肺移植过程中显著上调。 过敏性炎症引起的吸入挑战的屋尘螨（HDM）。此外，人类ASM 细胞表达tRNA的一半，并且它们的表达通过促炎和 Th 2细胞因子、肿瘤坏死因子α（TNF α）和白细胞介素13（IL-13）。这些结果使我们能够 将tRNA半体定义为一类新的依赖于精氨酸的tRNA半体，称为促炎性 tRNA衍生的RNA（pit-RNA）。重要的是，siRNA指导的pit-RNA的消耗显著地 损害了ASM细胞的增殖，这表明pit-RNA不仅在细胞内积累， 它们是tRNA的降解副产物，但表达为促进ASM细胞生长的功能性RNA。 这些结果使我们推测炎症介质在ASM中积累pit-RNA 细胞，在哮喘的分子发病机制中增强ASM生长。我们建议 全面鉴定pit-RNA表达谱（目的1）并研究pit-RNA表达的分子机制。 pit-RNA介导的ASM细胞功能调节（目的2），这将揭示一种新的tRNA参与的 小RNA通路在哮喘发病机制中的作用，并支持生物标志物的探索， 靶向tRNA半体的有效治疗应用。 .

Project Summary and Abstract Asthma is a chronic inflammatory disease characterized by inflammation, mucus production, airway remodeling, and hyper-responsiveness resulting in severe bronchoconstriction. These processes involve interplay among resident airway cells and infiltrated inflammatory cells. Allergic inflammatory mediators such as cytokines, chemokines, and growth factors act on resident airway cells including airway smooth muscle (ASM) resulting in structural and functional changes. However, knowledge gaps remain in our understanding of the molecular factors and mechanisms by which inflammatory mediators modulate ASM phenotype. Inflammatory mediators change gene expression and contribute to the pathogenesis of asthma. Transcriptional regulation of gene expression in resident airway cells has been studied extensively. However, protein function in a target cell can be regulated at multiple levels starting from transcription followed by post-transcription, translation and post-translation steps. In this context, small non-coding RNAs (ncRNAs) including the ones derived from transfer RNA (tRNA) have evolved as one of the key regulators of gene expression post-transcriptionally. We propose that tRNA halves, a major subgroup of tRNA-derived ncRNAs, play important roles in asthma pathobiology and can be targeted as asthma therapy. In preliminary studies, we found that mouse lung expresses specific tRNA half species whose levels are significantly upregulated during allergic inflammation caused by inhaled challenge of house dust mite (HDM). Furthermore, human ASM cells express tRNA halves and their expressions are promoted by treatments with pro-inflammatory and Th2 cytokines, tumor necrosis factor alpha (TNF) and interleukin 13 (IL-13). These results allow us to define the tRNA halves as a novel class of cytokine-dependent tRNA halves, termed proinflammatory tRNA-derived RNAs (pit-RNAs). Importantly, siRNA-directed depletion of pit-RNAs significantly impaired the proliferation of ASM cells, suggesting that pit-RNAs are not just accumulated as degradation by-products of tRNAs but are expressed as functional RNAs promoting ASM cell growth. These results have led us to hypothesize that inflammatory mediators accumulate pit-RNAs in ASM cells, which enhance ASM growth in the molecular pathogenesis of asthma. We propose to comprehensively identify pit-RNA expression profiles (Aim 1) and investigate molecular mechanisms of the pit-RNA-mediated modulation of ASM cell function (Aim 2), which will reveal a novel tRNA-engaged small RNA pathway in the pathogenesis of asthma and support the exploration of biomarkers and efficacious therapeutic applications targeting tRNA halves. .