Novel mechanism of smooth muscle phenotypic modulation and vascular remodeling

平滑肌表型调节和血管重塑的新机制

• 批准号: 8794466
• 负责人: Shiyou Chen
• 金额: $ 36.83万
• 依托单位: UNIVERSITY OF GEORGIA
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-02-01 至 2018-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8794466
• 关键词: 3' Untranslated Regions; ADAR1; Adenosine; Angioplasty; Ants; Arterial Disorder; Arteries; Atherosclerosis; Blood Platelets; Blood Vessels; Bypass; Cardiovascular Diseases; Carotid Arteries; Cell physiology; Contractile Proteins; Contracts; DRADA2b protein; Data; Development; Diabetic Angiopathies; Disease; Down-Regulation; Figs - dietary; Gene Expression; Genes; Goals; Growth; Health; Hyperplasia; Hypertension; Injury; Inosine; Introns; Knockout Mice; Lead; Mediating; Messenger RNA; Mining; Modeling; Molecular; Mus; Muscle; Myosin ATPase; Myosin Heavy Chains; Pathologic; Phenotype; Platelet-Derived Growth Factor; Play; Proteins; RNA Editing; RNA Splicing; Rattus; Regulation; Role; Seminal; Site; Smooth Muscle; Smooth Muscle Myocytes; Smooth Muscle Myosins; Steno; Testing; Therapeutic; Therapeutic Agents; Transcript; Translations; Transplantation; United States; Vascular Diseases; Vascular Proliferation; Vascular Smooth Muscle; Vascular remodeling; Veins; calponin; dsRNA adenosine deaminase; gain of function; genetic approach; in vivo; injured; loss of function; mRNA Precursor; migration; mortality; mouse model; neointima formation; novel; platelet-derived growth factor BB; protein expression; restenosis; small hairpin RNA; teration

DESCRIPTION (provided by applicant): Vascular smooth muscle (SMC) phenotypic modulation, the transition from a contractile to a proliferative phenotype accompanied by neointima formation following vascular injury, plays a critical role in the development and progression of several proliferative cardiovascular diseases such as atherosclerosis, hypertension, restenosis after angioplasty or bypass, diabetic vascular complications, and transplantation arteriopathy. The regulatory mechanisms underlying SMC phenotypic modulation, however, are poorly understood. A hallmark feature of the phenotypic modulation is the down-regulation of SMC contractile genes. Platelet-derived growth factor-BB (PDGF-BB), a well-known stimulator of SMC phenotypic modulation, down- regulates SMC gene expression and stimulates SMC proliferation via posttranscriptional regulation of the related genes. The post-transcriptional mechanisms involved in SMC phenotype gene expression, however, remain largely unknown. Our exciting preliminary data indicate that the down-regulation of SMC contractile genes is caused by abnormal RNA editing of their precursor mRNAs (pre-mRNAs). This abnormal pre-mRNA editing is facilitated by adenosine deaminase acting on RNA (ADAR), which converts adenosines to inosines (A->I editing). A-to-I RNA editing of the pre-mRNA transcripts from introns or 3'-untranslated regions alters pre- mRNA splicing, leading to decreased mature mRNA levels and abnormal cellular functions. PDGF-BB induces ADAR1 while down-regulating SMC myosin heavy chain (SMMHC) and calponin (CNN). Knockdown of ADAR1 by shRNA restores PDGF-BB-blocked SMMHC and CNN expression, demonstrating that ADAR1 plays an essential role in SMC phenotype modulation. ADAR1 appears to be also important for PDGF-BB-induced SMC proliferation/survival. In vivo studies show that SMMHC and CNN pre-mRNA is accumulated when their mature mRNA is decreased in balloon-injured rat carotid arteries. Moreover, ADAR1 is highly induced in media layer SMCs initially, and neointima SMCs subsequently following the injury. Of importance, knockdown of ADAR1 dramatically inhibits injury-induced neointima formation, demonstrating a critical role of ADAR1 in vascular remodeling in vivo. These seminal findings strongly support a novel hypothesis that ADAR1/abnormal RNA editing mediates PDGF-BB-induced down-regulation of SMC contractile genes and SMC proliferation/survival, leading to SMC phenotypic modulation and vascular remodeling. Using primary culture of SMCs, in vivo rat balloon injury and mouse wire injury models combining with molecular, cellular and histological approaches, we will 1) determine the role and mechanism whereby ADAR1 modulates SMC phenotype; 2) elucidate the molecular mechanisms underlying ADAR1 function in regulating SMC proliferation/survival; and 3) study the role of ADAR1 in SMC phenotypic modulation and vascular remodeling in vivo. Successful completion of these aims will unravel a novel mechanism governing SMC phenotypic modulation, which will ultimately lead to identification of novel targets for developing therapeuti agents to treat proliferative vascular diseases.

描述（由申请人提供）：血管平滑肌（SMC）表型调节，即血管损伤后伴随新生内膜形成的从收缩表型到增殖表型的转变，在几种增殖性心血管疾病（如动脉粥样硬化、高血压、血管成形术或搭桥术后再狭窄、糖尿病血管并发症和移植动脉病）的发生和进展中起关键作用。然而，SMC表型调节的调控机制尚不清楚。表型调节的一个标志性特征是SMC收缩基因的下调。血小板衍生生长因子-BB（PDGF-BB）是一种众所周知的SMC表型调节刺激因子，其通过相关基因的转录后调节下调SMC基因表达并刺激SMC增殖。然而，参与SMC表型基因表达的转录后机制在很大程度上仍然未知。我们令人兴奋的初步数据表明，SMC收缩基因的下调是由其前体mRNA（pre-mRNAs）的异常RNA编辑引起的。这种异常的前体mRNA编辑由作用于RNA的腺苷脱氨酶（阿达尔）促进，其将腺苷转化为肌苷（A->I编辑）。来自内含子或3 '-非翻译区的前体mRNA转录物的A至I RNA编辑改变了前体mRNA剪接，导致成熟mRNA水平降低和细胞功能异常。PDGF-BB诱导ADAR 1，同时下调SMC肌球蛋白重链（SMMHC）和钙调蛋白（CNN）。通过shRNA敲低ADAR 1恢复PDGF-BB阻断的SMMHC和CNN表达，表明ADAR 1在SMC表型调节中起重要作用。ADAR 1似乎对PDGF-BB诱导的SMC增殖/存活也很重要。体内研究表明，当球囊损伤大鼠颈动脉中SMMHC和CNN前mRNA的成熟mRNA减少时，它们会积累。此外，ADAR 1最初在中膜层SMC中高度诱导，随后在损伤后的新生内膜SMC中高度诱导。重要的是，ADAR 1的敲低显著抑制损伤诱导的新生内膜形成，证明了ADAR 1在体内血管重塑中的关键作用。这些开创性的发现有力地支持了一个新的假设，即ADAR 1/异常RNA编辑介导PDGF-BB诱导的SMC收缩基因和SMC增殖/存活的下调，导致SMC表型调节和血管重塑。本研究将利用原代培养的SMC、大鼠球囊损伤模型和小鼠钢丝损伤模型，结合分子、细胞和组织学方法，探讨ADAR 1对SMC表型的调控作用和机制;阐明ADAR 1调控SMC增殖/存活的分子机制;研究ADAR 1在SMC表型调控和血管重塑中的作用。这些目标的成功完成将揭开一个新的机制，管理SMC表型调节，这将最终导致识别新的目标，开发治疗剂，以治疗增殖性血管疾病。