Role of rRNA-derived short non-coding RNAs in innate immune response

项目摘要和摘要 微生物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机制是开发有效预防措施的关键 方法和治疗应用。先天免疫系统部署了各种模式识别受体， 包括Toll样受体(TLRs)，识别微生物的入侵并启动保护性反应。 TLRs在细胞表面或细胞内隔间(例如，内小体和溶酶体)以不同的方式表达 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 最终导致转录因子如NF-B激活的途径，导致产生 保护宿主的细胞因子和趋化因子。在转录调控之后，TLR的下游 通路涉及多个水平的调控，包括转录后步骤。在这方面，简短的非- 编码RNA(NcRNAs)已经进化为关键的转录后调节因子。在各种短的ncRNA中 来自核糖体RNA(RRNAs)的物种，被称为rRNA片段(RRFs)，是最丰富的一类 短小的ncRNAs，近年来对其表达和功能意义的研究越来越受到重视。 RRFs在包括人类在内的多种生物中结构性表达，它们的表达参与了 调节细胞周期和增殖、细胞凋亡以及脂肪和葡萄糖代谢。在人类身上，他们的 表达是以性别和人群特有的方式调节的，并与2型糖尿病和其他 疾病。我们认为rRFs在先天免疫反应中起重要作用。在初步研究中，我们 发现人单核细胞表面TLR的激活上调了rRFs的表达 巨噬细胞(HMDM)。重要的是，短的ncRNA测序数据显示了丰富的积累 不仅在HMDM中，而且在它们分泌的细胞外载体(EVS)中也有rRFs的表达。进一步的实验 结果表明，特定的细胞外RRF激活受体HMDM中的内体TLR以诱导细胞因子 分泌，这表明rRFs不仅作为rRNA的降解副产物积累，而且 作为促进免疫反应的功能分子积累起来。在建议的研究中，我们会确定 TLR途径诱导的rRFs在HMDM及其EV中的表达谱(目标1)。我们将进一步澄清 胞外rRFs在内体TLR激活中的分子功能(目标2)。最后，我们将描述 RRF在健康人和结核分枝杆菌感染者血浆中的表达 (目标3)。通过定义一类新的TLR途径诱导的rRFs并进一步确定它们的作用，我们的研究 将揭示一种新的rrna参与的ncRNA途径在先天免疫反应中，并可能支持未来 针对ncRNAs的微生物感染生物标志物和有效治疗应用的探索。

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-B, 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) have evolved as key post-transcriptional regulators. Among various short ncRNA species, those from ribosomal RNAs (rRNAs), termed rRNA fragments (rRFs), are the most abundant class of short ncRNAs and have recently gained increasing attentions on their expression and functional significance. rRFs are constitutively expressed in multiple organisms including humans, and their expression is involved in regulation of cell cycle and proliferation, apoptosis, and lipid and glucose metabolism. In humans, their expression is modulated in a sex- and population-specific manner, and associated with type 2 diabetes and other diseases. We propose that rRFs play important roles in innate immune response. In preliminary studies, we found that the expression of rRFs is upregulated by the activation of surface TLR in human monocyte-derived macrophages (HMDMs). Importantly, short ncRNA sequencing data demonstrated the abundant accumulation of the rRFs not only in HMDMs but also in their secreted extracellular vehicles (EVs). Further experiments showed that a specific extracellular rRF activates endosomal TLR in the recipient HMDMs to induce cytokine secretion, suggesting that rRFs are not just accumulated as degradation by-products of rRNAs, but are accumulated as functional molecules promoting immune response. In the proposed studies, we will identify the expression profiles of TLR pathway-induced rRFs in HMDMs and their EVs (Aim 1). We will further elucidate the molecular function of extracellular rRFs in endosomal TLR activation (Aim 2). Finally, we will characterize the rRF expression in plasma samples from healthy subjects and patients infected with Mycobacterium tuberculosis (Aim 3). By defining a novel class of TLR pathway-induced rRFs and further establishing their roles, our study will reveal a novel rRNA-engaged ncRNA pathway in the innate immune response and may support the future exploration of biomarkers and efficacious therapeutic applications targeting ncRNAs upon microbe infection.