Significance of microRNA-mediated gene regulation in chronic neuropathic pain

描述（申请人提供）：神经性疼痛是一种由神经系统损伤或疾病引起的慢性疼痛。这种疾病已被证明特别难以临床治疗，因为其发展和维持的基本机制还不清楚。因此，显然需要确定负责这种病理性疼痛的新分子或生物过程，可以开发新的治疗策略。本研究项目的长期目标是了解对神经性疼痛表现至关重要的基因调控机制。该特定应用的目的是鉴定在慢性神经性疼痛病症中起关键作用的microRNA及其调节靶标。MicroRNA是基因组编码的一类新的非蛋白质编码小RNA分子，主要在转录后水平调控基因表达，发挥多种生物学功能。特别是，microRNAs最近被认为与神经系统的可塑性有关。由于神经性疼痛可以被认为是疼痛传递途径中神经可塑性的不受欢迎的结果，因此高度期望microRNA参与神经性疼痛。这项研究的中心假设是，神经损伤诱导特定microRNA表达的变化，而这些microRNA反过来又调节一组促伤害感受和抗伤害感受蛋白的表达，从而导致长期慢性疼痛状态。这项研究的基本原理是，一旦特定的microRNA被鉴定为神经性疼痛条件下疼痛相关蛋白的调节剂，就有可能通过调节这些microRNA的水平来控制神经性疼痛，无论是通过免疫或分子生物学策略。因此，拟议的研究预计将导致基础知识的发展，这将可能有助于减少人类残疾的负担。根据积极的初步数据，将追求两个具体目标。它们将：1）鉴定参与神经性疼痛的发展和维持的microRNA;和2）鉴定神经性疼痛相关microRNA的靶基因。对于第一个目标，将使用微阵列技术和其他分子生物学方法来寻找在引起神经病理性疼痛的脊神经损伤后表现出显著表达水平差异的microRNA。对于第二个目标，计算方法以及组织化学方法将用于识别在神经损伤引起的疼痛传递途径中可能受特定microRNA调控的基因。这个提议是新颖的，因为microRNA在神经性疼痛中的可能功能从未被研究过。它也很重要，因为它有望引发一个新的研究领域，重点是microRNA在慢性疼痛中的功能，这将促进对与慢性疼痛相关的基因调控的理解。 公共卫生相关性：该项目涉及一个未探索的研究领域，预计将导致更好地了解负责慢性神经性疼痛的发展和维持的基本机制。该项目与公共卫生相关，因为一旦microRNA在慢性神经性疼痛中的功能被鉴定和表征，它们将成为这种严重疾病的极好的新治疗靶点。

DESCRIPTION (provided by applicant): Neuropathic pain is a type of chronic pain caused by injury or disease of the nervous system. This disorder has proven particularly difficult to treat clinically, because the fundamental mechanisms for its development and maintenance are not well understood. As a result, there is an obvious need to identify novel molecules or biological processes responsible for this pathological pain, against which new therapeutic strategies can be developed. The long-term goal of this research project is to understand the mechanisms of gene regulation critically important for the manifestation of neuropathic pain. The objective of this particular application is to identify microRNAs and their regulatory targets that play key roles in the chronic neuropathic pain condition. MicroRNAs are a new class of non-protein-coding small RNA molecules that are encoded by the genome, which regulate gene expression mainly at the post-transcriptional level and play a variety of biological functions. In particular, microRNAs have recently been implicated in the plasticity of the nervous system. Because neuropathic pain can be considered as an unwelcome consequence of the neural plasticity in the pain transmission pathways, the involvement of microRNAs in neuropathic pain is highly anticipated. The central hypothesis for the proposed research is that nerve injury induces changes in expression of particular microRNAs, which in turn regulate expression of a set of pro-nociceptive and anti-nociceptive proteins, contributing to long-lasting chronic pain states. The rationale for the proposed research is that, once particular microRNAs are identified as regulators of pain-related proteins in the neuropathic pain conditions, it would become possible to control neuropathic pain by modulating the levels of those microRNAs either pharmacologically or through molecular biological strategies. Thus, the proposed research is expected to lead to the development of fundamental knowledge that will potentially help to reduce the burdens of human disability. Based on positive preliminary data, two specific aims will be pursued. They are to: 1) identify microRNAs involved in the development and maintenance of neuropathic pain; and 2) identify target genes for the neuropathic pain-related microRNAs. For the first aim, the microarray technology and other molecular biological methods will be used to find microRNAs that show significant differences in expression levels after spinal nerve injury that causes neuropathic pain. For the second aim, the computational methods as well as histochemical approaches will be used to identify genes that are potentially regulated by particular microRNAs in the pain transmission pathways in response to nerve injury. This proposal is novel, because the possible functions of microRNAs in neuropathic pain have never been investigated. It is also significant, because it is expected to trigger a new field of research focusing on microRNA function in chronic pain, which would advance understanding of gene regulation associated with the chronic pain conditions. PUBLIC HEALTH RELEVANCE: This proposed project concerns an unexplored area of research that is expected to lead to a better understanding of the fundamental mechanisms responsible for the development and maintenance of chronic neuropathic pain. The project has relevance to public health, because once microRNA's functions in chronic neuropathic pain are identified and characterized, they would be excellent new therapeutic targets for this serious disorder.