Elucidating the Cellular and Molecular Mechanisms of Late-Onset Scoliosis

描述(申请人提供)：青少年特发性脊柱侧凸(AIS)是最常见的儿童脊柱畸形，影响2-3%的学龄儿童，经常需要医疗干预，如支具或手术。尽管AIS给儿童、父母和医疗保健系统带来了巨大的负担，但人们对AIS的病因知之甚少。在一定程度上，这是由于缺乏遗传上易处理的脊柱侧弯动物模型。为此，我将研究一种新的显性插入斑马鱼突变体Druk的轴曲率形成和发展的细胞和分子机制。有趣的是，Druk显示了人类AIS的可能推论，例如轴柱的渐进性弯曲，从幼虫期开始没有椎骨畸形。我已经确定了两个基因，mon1a和mstr1rb，直接位于Druk插入的两侧，在Druk突变鱼中表现出转录上调。我假设德鲁克产生了一个或两个侧翼基因的分子功能增益。我将直接测试这些基因的过度表达是否足以在幼鱼身上产生腋曲。AIS的多种机制已被提出，包括沿轴柱的肌腱连接丢失以及全身性骨密度(BMD)丢失。成年Druk FISH的X-射线显微断层扫描(？-CT)分析显示，轴柱骨密度显著降低。我推测，异常的骨代谢可能先于Druk诱发的轴向弯曲的进展。为了测试这一点，我将询问破骨细胞、成骨细胞的活动或沿轴柱的肌腱连接的异常发展是否与Druk突变表型有关。这项建议旨在确定斑马鱼幼体中遗传易受控制的轴柱曲率的起源和发展的细胞和分子机制，类似于人类AIS的特征。这些结果可能提供脊柱侧弯基因座的遗传证据，这将有助于人类的早期发现。最后，德鲁克突变体将增强我们对脊柱侧弯病因的理解，并可能成为开发新的药物疗法以对抗人类AIS的典范。

DESCRIPTION (provided by applicant): Adolescent idiopathic scoliosis (AIS) is the most common pediatric spinal deformity, which affects 2-3% of school age children and often necessitates medical intervention such as bracing or surgery. Despite a significant burden to children, parents and health care systems; the etiology of AIS is poorly understood. In part, this is due to a lack of genetically tractable animal models of scoliosis. For this reason, I will investigate cellular and molecular mechanisms of the formation and progression of axial curvatures in a novel dominant insertional zebrafish mutant, druk. Interestingly, druk displays possible corollaries to human AIS such as progressive curvature of the axial column without malformation of vertebrae beginning at larval stages. I have determined that two genes, mon1a and mstr1rb, immediately flanking the druk insertion exhibit transcriptional upregulation in druk mutant fish. I hypothesize that druk produces a molecular gain-of-function of one or both flanking genes. I will directly test if overexpression of these genes is sufficient to generate axil curvatures in larval fish. Multiple mechanisms have been proposed for AIS including loss of myotendenous connections along the axial column as well as generalized loss of bone mineral density (BMD). X-ray microtomography (¿-CT) analysis of adult druk fish showed a significant decrease in BMD of the axial column. I hypothesize that abnormal bone metabolism may precede the progression of druk induced axial curvature. To test this, I will ask if the activity o osteoclasts, osteoblasts or the abnormal development of myotendinous junctions along the axial column contributes to the druk mutant phenotype. This proposal aims to define the cellular and molecular mechanisms of the origin and progression of genetically tractable axial column curvatures in a larval zebrafish, akin to characteristics of AIS in humans. These results may provide genetic evidence of a scoliosis locus that will assist early detection in humans. Finally, the druk mutant will enhance our understanding of the etiology of scoliosis and possibly serve as a model for the development of novel pharmacological therapies to combat AIS in humans.