Role of Toll-like receptor-induced short non-coding RNAs in innate immune response

项目概要和摘要 微生物的感染会引起广泛的症状和疾病。持续努力了解 针对微生物感染的细胞防御系统的机制对于开发有效的预防是必不可少的 方法和治疗应用。先天免疫系统部署各种模式识别受体， 包括Toll样受体（TLR），以识别微生物的入侵并启动保护性反应。 TLR在细胞表面或细胞内区室（例如，内体和溶酶体）在各种 细胞类型，如巨噬细胞，并识别病原体相关分子模式（PAMP），如 脂多糖（LPS）和肽聚糖（PGN）。PAMP识别启动信号转导 最终激活转录因子如NF-κB的途径，导致 细胞因子和趋化因子来保护宿主。在转录调控之后，TLR的下游 途径涉及多个水平的调节，包括转录后步骤。在这种情况下，短期非 编码RNA（ncRNA），包括那些来自转移RNA（tRNAs）已经演变为关键的后- 转录调节因子。tRNA半体构成tRNA衍生的ncRNA的主要亚组，并且已经被 显示表达为与各种生物学途径相关的功能性RNA，并与人类 例如神经变性疾病和癌症。我们提出的研究的目标是阐明 tRNA半分子的表达谱和分子功能，其积累参与先天性 免疫反应我们最近发现，牛分枝杆菌BCG感染上调表达， 人单核细胞衍生的巨噬细胞（HMDM）中tRNA的一半。此外，tRNA的表达 HMDM中的半部分通过表面膜TLR的激活而上调，使我们能够定义tRNA 半作为一类新的TLR途径依赖的tRNA半。重要的是，tRNA的一半是丰富的， 不仅在TLR途径激活的HMDM中积累，而且在其细胞外载体（EV）中积累， 在激活内体TLR途径中的功能意义，表明这些tRNA半体是 表达为促进免疫应答的功能性分子。这些结果让我们假设， tRNA半体可以是先天免疫应答中的组成部分。我们建议全面识别 TLR途径诱导的tRNA半体在HMDM及其EV中的表达谱（目的1），以研究 TLR途径如何诱导tRNA产生的生物发生机制（目的2），以及 阐明内体TLR激活中tRNA半体的分子功能（目的3）。我们的研究将揭示 新的tRNA参与的ncRNA途径在先天免疫反应，并可能支持未来的探索， 生物标志物和在微生物感染时靶向tRNA半分子的有效治疗应用。

Project Summary and Abstract Infection of microbes causes a wide range of symptoms and diseases. Sustained efforts to understand the mechanism of cellular defense systems against microbe infections are essential to develop effective prevention methods and therapeutic applications. The innate immune system deploys various pattern-recognition receptors, including Toll-like receptors (TLRs), to recognize the invasion of microbes and initiate protective responses. TLRs are expressed at the cell surface or intracellular compartments (e.g., endosome and lysosome) in various cell types, such as macrophages, and recognize pathogen-associated molecular patterns (PAMPs) such as lipopolysaccharide (LPS) and peptidoglycan (PGN). The PAMP recognition initiates signal transduction pathways that culminate in the activation of transcription factors such as NF-κB, resulting in production of cytokines and chemokines to protect the host. Following transcriptional regulation, the downstream of TLR pathways involves regulation at multiple levels including post-transcription steps. In this context, short non- coding RNAs (ncRNAs) including those derived from transfer RNAs (tRNAs) have evolved as key post- transcriptional regulators. tRNA halves constitute a major subgroup of tRNA-derived ncRNAs and have been shown to be expressed as functional RNAs associated with various biological pathways and linked to human diseases such as neurodegenerative diseases and cancers. The goal of our proposed studies is to elucidate the expression profile and molecular function of tRNA half molecules whose accumulation is involved in the innate immune response. We recently found that the infection of Mycobacterium bovis BCG upregulates the expression of tRNA halves in human monocyte-derived macrophages (HMDMs). Furthermore, the expression of tRNA halves in HMDMs is upregulated by the activation of surface membrane TLRs, allowing us to define the tRNA halves as a novel class of TLR pathway-dependent tRNA halves. Importantly, tRNA halves are abundantly accumulated not only in TLR pathway-activated HMDMs but also in their extracellular vehicles (EVs) and have functional significance in activation of endosomal TLR pathway, suggesting that those tRNA halves are expressed as functional molecules promoting immune response. These results have led us to hypothesize that tRNA halves can be integral elements in the innate immune response. We propose to comprehensively identify the expression profiles of TLR pathway-induced tRNA halves in HMDMs and their EVs (Aim 1), to investigate the biogenesis mechanism how the production of tRNA haves are induced by TLR pathways (Aim 2), and to elucidate the molecular function of tRNA halves in endosomal TLR activation (Aim 3). Our study will reveal a novel tRNA-engaged ncRNA pathway in the innate immune response and may support the future exploration of biomarkers and efficacious therapeutic applications targeting tRNA half molecules upon microbe infection.