Elucidating the Cellular and Molecular Mechanisms of Late-Onset Scoliosis

描述（由申请人提供）：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，通常需要支架或手术等医疗干预。尽管对儿童、父母和卫生保健系统造成了重大负担；AIS的病因尚不清楚。在某种程度上，这是由于缺乏遗传上易于处理的脊柱侧凸动物模型。因此，我将研究一种新的显性插入斑马鱼突变体druk的轴向曲率形成和进展的细胞和分子机制。有趣的是，druk表现出可能与人类AIS的必然结果，例如从幼虫阶段开始，轴柱逐渐弯曲，但椎骨没有畸形。我已经确定了两个基因，mon1a和mstr1rb，紧挨着druk插入，在druk突变鱼中表现出转录上调。我假设醉酒会产生一个或两个侧面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中产生腋窝弯曲。AIS的多种机制已被提出，包括沿轴向柱的肌倾向连接丧失以及骨矿物质密度（BMD）的广泛性丧失。成年醉鱼的x射线微断层扫描（¿-CT）分析显示，中轴柱骨密度明显下降。我推测异常的骨代谢可能先于醉酒引起的轴向弯曲的进展。为了验证这一点，我将询问破骨细胞、成骨细胞的活性或沿轴向柱的肌腱连接的异常发育是否导致了醉酒突变表型。本研究旨在确定斑马鱼幼虫的轴向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凸位点的遗传证据，有助于人类的早期检测。最后，醉酒突变体将增强我们对脊柱侧凸病因的理解，并可能作为开发新型药物治疗人类AIS的模型。

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.