Marfan Aortic Embryologic Origin Influences miR-29b Regulators and Targets

 描述(申请人提供)：马凡综合征(MFS)是一种常染色体显性的全身性结缔组织疾病，每5000人中就有1人患病。患有MFS的患者通常会发展为主动脉根部动脉瘤，随后的主动脉夹层或破裂仍然是主要的死亡原因。以往的研究表明，MFS中潜在的纤维蛋白-1基因突变增加了转化生长因子-β(转化生长因子-β)的活性。尽管阻断转化生长因子-β抑制了MFS模型小鼠主动脉根部动脉瘤的发展，但转化生长因子-β信号导致动脉瘤发展的分子机制仍不清楚。MicroRNAs(MiRNAs)是一种短的非编码单链RNA，其功能是调节数百个基因。我们的实验室已报道miR-29b在Marfan小鼠模型(Fbn1C1039G/+)的早期动脉瘤发展中起关键致病作用。已知的是，MIR-29b调节与细胞凋亡和细胞外基质沉积/重塑有关的基因。重要的是，转化生长因子-β如何增加miR-29b在出生后早期在时间和空间上局限于主动脉根部的表达尚不清楚。主动脉是一个由内膜、中膜和外膜三层组成的异质结构。谱系研究表明，主动脉不同解剖段的血管平滑肌细胞(SMC)具有不同的胚胎学起源。最近的研究表明，SMC起源的多样性可能解释了动脉瘤发生的部位特异性。本实验室从人MFS患者体内培养出诱导多能干细胞(IPS)，并成功地将其分化为来自不同胚胎来源(第二心区、神经脊细胞和旁中胚层)的SMC。这个体外模型系统将使我们能够研究SMC起源如何影响动脉瘤形成的区域差异。补充实验将使用体内的马凡动物模型进行，从而增加这些研究的翻译潜力。总体工作假说是，不同胚胎来源的平滑肌细胞会导致不同的miR-29b介导的细胞外基质重塑，并导致马凡综合征主动脉根部动脉瘤的形成，这一假说将通过以下两个具体目标进行验证：目标1：确定不同胚胎来源的马凡人诱导多能干细胞(IPSC)来源的血管SMCs中，miR-29b的上游调节因子和下游靶点是否不同。目的：利用Fbn1C1039G/+(主动脉根部；第二心区)和Ang II ApoE(腹部；中胚层)小鼠模型，比较miR-29b在不同胚胎来源的主动脉段动脉瘤形成中的作用。这一建议将提供一个解释MFS中动脉瘤发展的机制框架。研究参与主动脉根部细胞外基质(ECM)退变的具体途径可能会转化为更具解剖学指导的治疗方法。

 DESCRIPTION (provided by applicant): Marfan syndrome (MFS) is an autosomal-dominant systemic connective tissue disorder that affects 1 in 5000 individuals. Patients with MFS typically develop aortic root aneurysms with ensuing aortic dissection or rupture remaining the leading cause of death. Previous studies have demonstrated that the underlying fibrillin-1 gene mutation in MFS increases the activity of transforming growth factor-β (TGF-β). Although TGF-β blockade inhibits aortic root aneurysm development in murine models of MFS, the molecular mechanism by which TGF- β signaling leads to aneurysm development remains unknown. MicroRNAs (miRNAs) are short non-coding single-stranded RNAs that function to regulate hundreds of genes. Our laboratory has reported that miR-29b plays a key pathogenic role in early aneurysm development in a Marfan mouse model (Fbn1C1039G/+). miR-29b is known to regulate genes involved in apoptosis and ECM deposition/remodeling. Importantly, how TGF-β increases miR-29b expression in a manner that is temporally and spatially restricted to the aortic root during early postnatal life, is not clear. The aorta is a heterogeneous structure composed of three layers, the intima, media and adventitia. Lineage studies have shown that vascular smooth muscle cells (SMC) in the different anatomic segments of the aorta have distinct embryological origins. Recent studies have suggested that the diversity of SMC origin may explain site specific location of aneurysm development. Our laboratory has developed induced-pluripotent stem (iPS) cells from human MFS patients and have successfully differentiated them into SMC from different embryologic origins (second heart field, neural crest cells and paraxial mesoderm). This in vitro model system will allow us to study how SMC origin influences regional differences in aneurysm formation. Complementary experiments will be performed using an in vivo Marfan animal model, thus increasing the translational potential of these studies. The overall working hypothesis that differences in the embryonic origin of smooth muscle cells lead to distinct miR-29b-mediated extracellular matrix remodeling and contributes to aortic root aneurysm formation in Marfan syndrome will be tested by the following two specific aims: AIM 1: Determine if the miR-29b upstream regulators and downstream targets are different in Marfan human induced pluripotent stem cell (iPSC)-derived vascular SMCs from different embryologic origins. AIM 2: Contrast the role of miR-29b in the development of aneurysms within aortic segments originating from distinct embryonic origins utilizing the Fbn1C1039G/+ (aortic root; second heart field) and Ang II ApoE (abdominal; mesoderm) mouse models. This proposal will provide a mechanistic framework explaining aneurysm development in MFS. Investigating the pathways that participate in extracellular matrix (ECM) degeneration in the aortic root specifically might translate into more anatomically directed therapeutics.