Novel role of the lncRNA NEAT1 in smooth muscle phenotypic modulation

 描述(申请人提供)：拟议研究的总体目标是确定先前未知的(长非编码RNA)lncRNA NEAT1(核副斑点组装转录本1)的作用及其在调节血管平滑肌细胞(VSMCs)表型转换方面的新的潜在机制。人类的许多血管疾病，如血管成形术后的内膜增生，在很大程度上依赖于VSMC表型从收缩表型向合成表型的转变，这种表型与平滑肌特异性基因表达减少以及细胞增殖和迁移增加相关。因此，弄清VSMC表型转换的机制对于了解VSMC相关血管疾病的病理机制和最终设计治疗药物至关重要。越来越多的证据表明，lncRNAs代表了一类新的基因表达调控因子。为了寻找与血管损伤相关的lncRNA，我们使用球囊剥离损伤的大鼠颈动脉进行了大规模的lncRNA阵列筛选，这一过程类似于人类的血管成形术。这一筛选表明，在体内诱导的lncRNA NEAT1是对动脉损伤的反应。此外，NEAT1的表达也可在体外的平滑肌表型转换的刺激下被诱导。功能丧失和功能获得的NEAT1表明，NEAT1不仅促进VSMCs的增殖和迁移，而且还减少了平滑肌特异性收缩蛋白的表达。因此，这项建议中描述的实验将检验这一假设，即NEAT1的诱导在促进平滑肌表型转换方面起着关键作用。在目标1中，我们将确定NEAT1在动脉损伤后新生内膜增生中的作用。我们将在对照组和NEAT1基因敲除的小鼠进行股动脉钢丝损伤，并评估NEAT1KO对新生内膜增生进展的影响。在目标2中，我们将确定NEAT1抑制平滑肌特异性基因表达的机制。具体地说，我们将评估WDR5在介导VSMC中NEAT1功能中的作用。WDR5是一种关键的组蛋白修饰物，用于诱导染色质的活性形式。在目标3中，我们将通过测试在NEAT1近端启动子中发现的进化保守的cAMP反应元件的作用来确定NEAT1转录在平滑肌表型调节刺激下上调的机制。这些研究的完成将为控制平滑肌表型转换的机制提供新的见解，并确定阻止NEAT1的诱导是否可能是改善闭塞性血管疾病的一种有吸引力的治疗策略。

 DESCRIPTION (provided by applicant): The overall goal of the proposed research is to determine the previously unrecognized role of the (long non-coding RNA) lncRNA NEAT1 (nuclear paraspeckle assembly transcript 1) and its novel underlying mechanism in regulating the phenotypic switching of vascular smooth muscle cells (VSMCs). Many vascular diseases in humans, such as intimal hyperplasia post-angioplasty, are largely dependent upon VSMC phenotypic switching from a contractile to a "synthetic" phenotype that is associated with reduced smooth muscle-specific gene expression and increased cell proliferation and migration. Therefore, unraveling the mechanisms for the VSMC phenotypic switching is crucial for understanding the pathology of VSMC related vascular diseases and ultimately designing therapeutic agents for treatment. Emerging evidences demonstrate that lncRNAs represent a novel class of regulators for gene expression. In an effort to search for lncRNAs involved in the vascular injury, we conducted a large-scale lncRNA array screen using the rat carotid artery injured by a balloon denudation, a procedure resembling angioplasty in humans. This screen revealed that the lncRNA NEAT1 is induced in response to the arterial injury in vivo. Furthermore, expression of NEAT1 is also induced upon the stimulation of smooth muscle phenotypic modulation in vitro. Loss- and gain-of-function NEAT1 revealed that NEAT1 not only increases proliferation and migration of VSMCs but also decreases expression of smooth muscle-specific contractile proteins. Therefore, experiments described in this proposal will test the hypothesis that, the induction of NEAT1 plays a critical role in promoting smooth muscle phenotypic switching. In Aim 1, we will determine the role of NEAT1 in neointima hyperplasia following arterial injury. We will perform femoral artery wire injuries in the control and NEAT1 knock out mice and assess the effects of NEAT1 KO on the progression of neointima hyperplasia. In Aim 2, we will determine the mechanism by which NEAT1 abrogates smooth muscle-specific gene expression. Specifically we will evaluate the role of WDR5, a critical histone modifier for inducing an active form of chromatin, in mediating NEAT1 function in VSMCs. In Aim 3, we will determine the mechanism by which the transcription of NEAT1 is up-regulated upon the stimulation of smooth muscle phenotypic modulation by testing the role of an evolutionally conserved cAMP response element identified in the NEAT1 proximal promoter. Completion of these studies will provide novel insights into the mechanisms controlling smooth muscle phenotypic switching and determine if preventing the induction of NEAT1 may be an attractive therapeutic strategy for ameliorating occlusive vascular diseases.