Role of small RNAs in innate immunity and inflammation

描述(申请人提供)：小核糖核酸在先天免疫和炎症中的作用宿主对病毒的反应涉及先天和获得性免疫机制的激活。病毒持久性是由宿主防御反应受损引起的，是炎症的常见原因。一些研究表明，病原体的存在可以刺激炎症介导的肿瘤发展。因此，我们的长期目标是了解参与抗病毒反应的宿主信号机制的调节，以及先天免疫过程调节失调引起的慢性炎症如何促进肿瘤发生。病毒在感染细胞中通过核酸识别的Toll样受体(TLRs)或胞质Rig-I样受体(RLRs)识别。对病毒的早期反应包括产生I型干扰素(干扰素)，干扰素反过来诱导干扰素刺激基因(ISGs)的转录，并激活阻碍病毒复制的酶。病毒感染还上调了其他细胞因子，这些细胞因子可以增强先天和获得性免疫反应。在病毒感染过程中，代表病毒基因组或作为复制中间产物的双链RNA(DsRNAs)激活干扰素诱导的2‘，5’-寡腺苷合成酶(OAS)，将细胞内的ATP转化为独特的2‘，5’-连接的寡腺苷，2-5A。2-5A的三聚体和四聚体寡聚体激活了一种普遍存在的潜在的内切核酸酶--核糖核酸酶L，它在UpAp和UpUp部分的3‘端裂解病毒和细胞的单链区，从而释放具有双重结构的小RNA。我们最近报道，这些小的‘自身’RNA(由核糖核酸酶L作用产生的细胞RNA的切割产物)可以通过诱导干扰素的合成来增强抗病毒的先天免疫。我们的初步数据使我们假设，由核糖核酸酶L激活产生的小RNA也诱导促炎细胞因子和促凋亡途径。这一假说是基于对核糖核酸酶L的观察：1)诱导ISGs和抗肿瘤基因的转录，2)诱导趋化因子和细胞因子，3)激活凋亡信号通路。识别参与这一过程的相关小RNA可以为开发新的抗肿瘤和抗病毒治疗策略提供基础。其具体目的是：1)研究RNaseL的小RNA裂解产物启动的信号通路；2)克隆和鉴定RNase L1产生的小细胞RNA；3)开发小RNA作为免疫刺激剂。了解核糖核酸酶L产生的小RNA在宿主反应中的作用，可以为抑制病毒感染和炎症提供新的策略。 公共卫生相关性：宿主对病毒的过度反应可能导致不受控制的炎症，从而导致组织损伤和可能的自身免疫反应，而反应不足则会导致病毒传播及其相关的细胞病变。我们的工作重点是宿主蛋白核糖核酸酶L在先天性免疫反应中的作用，在这项资助中，我们希望进一步了解核糖核酸酶L产生的小RNA在诱导促炎细胞因子和抗肿瘤或促凋亡基因中的作用。

DESCRIPTION (provided by applicant): ROLE OF SMALL RNAS IN INNATE IMMUNITY AND INFLAMMATION Host responses against viruses involve activation of both innate and adaptive immune mechanisms. Viral persistence, caused by impaired host defense responses, is a common cause of inflammation. Several studies have indicated that presence of pathogens can stimulate inflammation-mediated tumor development. Thus, our long term goal is to understand the regulation of host signaling mechanisms that are involved in antiviral responses and how chronic inflammation arising from dysregulation of innate immune processes can promote tumorigenesis. Viruses are recognized in infected cells by the nucleic acid- recognizing Toll-like receptors (TLRs) or the cytosolic Rig-I-like receptors (RLRs). Early response to viruses includes production of type I interferon (IFN), which in turn induces the transcription of IFN-stimulated genes (ISGs) and activates enzymes that impede viral replication. Viral infections also upregulate other cytokines that can augment both innate and adaptive immune responses. During viral infections, double stranded RNAs (dsRNAs), representing viral genomes or produced as replicative intermediates, activate the IFN- inducible 2',5'- oligoadenylate synthetases (OAS), which convert cellular ATP to unique 2',5'- linked oligoadenylates, 2-5A. Trimeric and tetrameric oligomers of 2-5A activate a ubiquitous and latent endoribonuclease, RNase L, which cleaves viral and cellular single-stranded regions of RNA at the 3'end of UpAp and UpUp moieties, thereby releasing small RNAs with duplex structures. We recently reported that these small 'self'RNAs (cleavage products of cellular RNA generated by the action of RNase L) can amplify antiviral innate immunity by inducing IFN-¿ synthesis. Our preliminary data have led us to hypothesize that small RNAs generated by activation of RNase L also induces pro-inflammatory cytokines and pro-apoptotic pathways. This hypothesis is based on the observations that activation of RNase L 1) induces transcription of ISGs and antitumor genes, 2) induces chemokines and cytokines and 3) activates apoptotic signaling pathways. Identification of the relevant small RNAs involved with this process could provide a basis for development of novel antitumor and antiviral therapeutic strategies. The specific aims are: 1) Investigate the signaling pathway initiated by small RNA cleavage products of RNase L. 2) Clone and identify small cellular RNA generated by RNase L. 3) Develop small RNAs as immune stimulants. Understanding the role of small RNAs generated by RNase L in host response can provide new strategies to suppress viral infection and inflammation. PUBLIC HEALTH RELEVANCE: Excessive host response to virus may lead to uncontrolled inflammation leading to tissue damage and possible autoimmune responses, while an inadequate response allows viral spread and its associated cytopathicity. Our work focuses particularly on the role of the host protein RNase L in innate immune responses, and in this grant we hope to provide further understanding of the role of RNase L-generated small RNAs in inducing proinflammatory cytokines and anti-tumor or pro-apoptotic genes.