Modeling thoracic aortic aneurysm in zebrafish

斑马鱼胸主动脉瘤建模

• 批准号: 10223412
• 负责人: C. Geoffrey Burns
• 金额: $ 44.25万
• 依托单位: BOSTON CHILDREN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-01 至 2022-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10223412
• 关键词: Adoption; Affect; Aneurysm; Animals; Aorta; Aortic Aneurysm; Applications Grants; Automobile Driving; Binding Proteins; Bioinformatics; Blood Vessels; Caliber; Cell Culture Techniques; Cell Proliferation; Cells; Clinical Trials; Connective Tissue Diseases; Cytoskeleton; Data; Data Set; Disease; Dominant-Negative Mutation; Etiology; Gene Expression; Genetic Models; Goals; Heart; Heart Aneurysm; Human; Impairment; Individual; Innovative Therapy; Knowledge; Laboratories; Ligands; Loeys-Dietz Syndrome; Longevity; Mammals; Marfan Syndrome; Medical emergency; Methods; Modality; Modeling; Molecular Chaperones; Molecular Profiling; Morphogenesis; Mus; Mutation; Names; Pathogenesis; Pathway interactions; Patients; Phenotype; Phosphorylation; Plant Roots; Population; Prevention; Production; Proliferating; Publishing; Role; Rupture; Signal Transduction; Smooth Muscle; Smooth Muscle Myocytes; Source; Stress Fibers; Structure; Suggestion; Testing; Thoracic Aortic Aneurysm; Transforming Growth Factor beta; Translating; Uncertainty; Zebrafish; advanced disease; causal variant; design; experimental study; improved; innovation; insight; mouse model; mutant; myocardin; novel; novel lead compound; novel therapeutics; overexpression; premature; prevent; small molecule; tissue stress; transcriptome sequencing

Project Summary Thoracic aortic aneurysms (TAAs), occurring at the aortic root, are cardinal features of Marfan Syndrome (MFS) and Loeys-Dietz Syndrome (LDS) that significantly shorten the lifespans of affected individuals because they dissect and rupture. Causative mutations for MFS and LDS have implicated perturbed TGFβ signaling in TAA pathogenesis. However, considerable uncertainty and controversy abound regarding whether high and/or low TGFβ signaling drives aneurysm formation. Also unclear is whether the nearly universal increases in TGFβ effector phosphorylation (i.e. pSmad2/3 and pErk1/2), observed in advanced disease, are a primary cause or secondary consequence of aortic distention. Lastly, the cellular mechanism by which perturbed TGFβ signaling might promote aneurysm remains undefined. Unfortunately, a small molecule that showed promise in treating aneurysm in MFS mice recently failed in a clinical trial. We have isolated and begun characterizing a novel genetic model of TAA in zebrafish. Animals deficient in Latent-TGFβ binding proteins (Ltbps) 1 and 3 (ltbp1-/-; ltbp3-/-), molecules that sequester TGFβ ligands in the extra cellular matrix (ECM), rapidly develop impressive aneurysm of the cardiac outflow tract (OFT), a structure homologous to the aortic root in mammals, over a two-day period following grossly unperturbed OFT morphogenesis. We present preliminary data documenting several similarities between zebrafish and mammalian aneurysm. The shared features include: 1) greater than 50% increases in aortic diameter; 2) significantly increased phosphorylation of Smad2/3 and Erk1/2 in the aneurysm wall, indicative of high canonical and non-canonical TGFβ signaling, respectively; 3) disorganization of smooth muscle cells which contain prominent stress fibers; 4) a propensity to dissect and/or rupture; and 5) overlapping molecular signatures revealed through a bioinformatics comparison of our recently-acquired RNA-sequencing dataset with a published microarray dataset from MFS mice. Interestingly, we have discovered elevated expression of markers for highly differentiated “contractile” smooth muscle in the OFTs of mutant zebrafish prior to any visible evidence of aneurysm. To my knowledge, few laboratories have investigated gene expression changes in the aortic root prior to aneurysm emergence in mouse models of MFS and LDS. Therefore, this aspect of the phenotype is highly novel. I propose several innovative and hypothesis-driven experimental approaches designed to provide impactful mechanistic insights into TAA pathogenesis. The knowledge obtained will inform ongoing debates over disease mechanisms and bolster efforts to identify novel therapeutic modalities for preventing and treating aneurysmal disease. I propose two Specific Aims: 1) to test the hypothesis that elevated TGFβ signaling is necessary and sufficient to cause aortic aneurysm in zebrafish; and 2) to test the hypothesis that aberrant phenotypic modulation of smooth muscle cells undermines OFT maturation and stability in ltbp1-/-; ltpb3-/- animals.

项目概要 发生在主动脉根部的胸主动脉瘤 (TAAs) 是马凡综合征的主要特征 (MFS) 和 Loeys-Dietz 综合症 (LDS) 会显着缩短受影响个体的寿命，因为 MFS 和 LDS 的致病突变表明 TGFβ 信号传导受到干扰。 然而，关于 TAA 是否高和/或是否存在相当大的不确定性和争议。 低水平的 TGFβ 信号传导是否会导致动脉瘤的形成，这一点还不清楚。 在晚期疾病中观察到的效应磷酸化（即 pSmad2/3 和 pErk1/2）是主要原因或 主动脉扩张的次要后果最后，扰乱 TGFβ 信号传导的细胞机制。 不幸的是，一种小分子在治疗方面显示出了希望。 MFS 小鼠的动脉瘤最近在一项临床试验中失败。 我们已经在斑马鱼中分离并开始表征一种新的 TAA 遗传模型。 缺乏潜在 TGFβ 结合蛋白 (Ltbps) 1 和 3（ltbp1-/-；ltbp3-/-），这是隔离 TGFβ 的分子 细胞外基质（ECM）中的配体，迅速形成令人印象深刻的心脏流出道动脉瘤 （OFT），一种与哺乳动物主动脉根结构同源的结构，在严重严重后的两天内 我们提供了初步数据，记录了未受干扰的 OFT 形态发生。 斑马鱼和哺乳动物的动脉瘤的共同特征包括：1）主动脉瘤增大超过50%。 直径；2) 动脉瘤壁中 Smad2/3 和 Erk1/2 的磷酸化显着增加，这是 分别高规范和非规范 TGFβ 信号传导；3) 平滑肌细胞的解体； 含有突出的应力纤维；4) 解剖和/或破裂的倾向；以及 5) 重叠分子； 通过我们最近获得的 RNA 测序数据集的生物信息学比较揭示的特征 已发布的 MFS 小鼠微阵列数据集。 突变斑马鱼 OFT 中高度分化的“收缩”平滑肌的标记 据我所知，很少有实验室研究过基因表达变化。 因此，在 MFS 和 LDS 小鼠模型中，主动脉根部出现动脉瘤之前。 我提出了几种创新和假设驱动的实验方法。 旨在为 TAA 发病机制提供有影响力的机制见解。所获得的知识将提供信息。 关于疾病机制的持续辩论，并加强努力确定新的治疗方式 我提出两个具体目标：1）检验以下假设： TGFβ 信号传导的升高对于引起斑马鱼的主动脉瘤是必要且充分的；2) 测试 平滑肌细胞的异常表型调节会破坏 OFT 成熟的假设 ltbp1-/- 动物中的稳定性；ltpb3-/- 动物。