KRT26基因突变导致一种新型脊柱发育不全的致病机制研究

Spinal Dysostoses, characterized by failure of vertebra formation or segmentation, are severe genetic skeletal disorders. The pathogenic genes and molecular mechanisms still remain unclear. A Chinese pedigree with spinal dysostoses was collected in the previous study. The major clinical features includes disproportionate short-trunk short stature, multiple vertebral anomalies and odontoid atlantoaxial absence. A new candidate gene, Keratin 26 (KRT26), was identified by whole exome sequencing and bioinformatics analysis. Keratins play critical roles in various cell functions such as cell signal transduction, cell transportation and intracellular compartmentalization. Krt26 was shown to be expressed in mouse embryonic spine and cartilage cell lines in our preliminary work, indicating that KRT26 may be involved in the spine development. In this project, Krt26 knock-out and Krt26 overexpression mouse chondrogenic cell lines will be established to study the role of KRT26 in chondrocyte differentiation and proliferation. A Krt26 knock-out mouse model will also be constructed and the phenotypes will be analyzed to investigate the impact of KRT26 on spine development. Omics-based methods combined with bioinformatics analysis and classical molecular biotechnology will be utilized to explore the signaling pathway regulated by Krt26. Thus we will elucidate the molecular mechanisms of Spinal Dysostoses caused by KRT26 mutations, and provide new insights into the research of the pathogenesis and treatment of spinal diseases.

脊柱发育不全是一类严重的遗传性骨病，以脊椎发育或分节障碍为特征，其致病基因和发病机制目前仍未完全明确。课题组前期收集了一个罕见的脊柱发育不全家系，其主要临床特征为短躯干型矮小、多发椎体形态异常以及寰枢椎齿状突缺失等。通过全外显子组测序及生物信息学分析，鉴定到新的候选致病基因角蛋白26（KRT26）。角蛋白在细胞信号转导、细胞运输、细胞内膜区室化等方面发挥关键作用。初步研究发现Krt26在小鼠胚胎脊柱及软骨细胞系中高表达，提示其可能参与脊柱发育。本项目拟建立Krt26敲除或过表达的小鼠成软骨细胞系，研究Krt26在软骨细胞分化增殖中的作用；通过构建Krt26敲除小鼠模型，分析表型，探讨其对脊柱发育的影响；利用组学和生物信息学、经典分子生物学等方法，在细胞和动物水平分析KRT26调控的信号转导通路。从而阐明KRT26基因突变导致脊柱发育不全的分子机制，为脊柱疾病的发病机理及治疗研究提供新思路。

脊柱发育不全是一类严重的遗传性骨病，以脊椎发育或分节障碍为特征，其致病基因和发病机制目前仍未完全明确。课题组收集了一个罕见的脊柱发育不全家系，其主要临床特征为短躯干型矮小、多发椎体形态异常以及寰枢椎齿状突缺失等。通过全外显子组测序及生物信息学分析，鉴定到新的候选致病基因角蛋白26（KRT26），患者带有KRT26基因的复合杂合变异（c.5delC,p.S2fs*84 和c.442-1G>C）。角蛋白在细胞信号转导、细胞运输、细胞内膜区室化等方面发挥关键作用。前期研究显示Krt26基因在小鼠胚胎脊柱及软骨细胞系中高表达，提示其可能参与脊柱发育。本项目构建了Krt26基因敲除小鼠模型，表型分析显示Krt26基因敲除小鼠未见脊柱发育异常，同时心、脑、肺、肌肉等主要器官组织也未见明显病理异常；利用小鼠模型胚胎肢芽细胞进行微团培养和成软骨细胞分化，结果显示Krt26基因敲除不影响间充质细胞向软骨细胞的分化。本研究结果提示Krt26基因不是小鼠骨骼发育的关键基因，Krt26基因敲除小鼠模型未能再现患者表型，可能是由于物种差异所导致。KRT26基因变异与人类脊柱发育不全之间的关系有待更多患者数据的支持。