FLNB基因突变在休门氏病发病中的机制研究

Scheuermann’s disease is an adolescent developmental spinal deformity mainly manifesting thoracic or thoracolumbar segments kyphosis with 0.4%-8% of incidence rate,which has a slight male dominance of about 7.3:1-1:1. The dominant role of genetic factors in Scheuermann’s disease has been corroborated by existing studies, whereas its pathogenesis is unclear. A new missense mutation，c.4625T>C (p.I1542T)，was identified in FLNB gene in the ways of whole-genome sequencing approach and bioinformatic analysis towards a Scheuermann’s disease family sample collected by our group before. Previous studies have shown that FLNB gene mutations can lead to disorders of endochondral ossification and abnormal proliferation and differentiation of chondrocytes, resulting in deformity of the skeletal system. The subject aims to observe the FLNB gene mutation effect on biological behavior of chondrocytes and endochondral ossification of vertebral endplate by induced pluripotent stem cells(iPSCs) derived from Scheuermann’s disease patients’ urine cells and flnb c.4625T>C mutation of mice models, and then to detect the regulatory effect of FLNB gene on the expression of mice endplate chondrocytes intracellular signaling pathway proteins by bioinformatics approach, hoping to illuminate the role of FLNB gene mutation in the pathogenesis of Scheuermann’s disease preliminarily.

休门氏病是以脊柱胸段或胸腰段后凸为主要临床表现的青少年发育性脊柱畸形，发病率约为0.4%-8%，多见于男性，男女比例为7.3:1-1:1，现有研究证实遗传因素在休门氏病发生中占主导作用，但其发病机制尚不明确。课题组前期收集了一个休门氏病家系样本，采用全基因组测序技术，经生物信息学分析，在FLNB基因确定一个新的错义突变 c.4625T>C (p.I1542T)。既往研究表明FLNB基因突变可以造成软骨内成骨障碍及软骨细胞分化增殖异常，导致骨骼系统发育畸形。本项目拟通过休门氏病患者尿源诱导多功能干细胞及flnb c.4625T>C 突变小鼠动物模型，观察FLNB基因突变对软骨细胞生物学行为和椎体终板软骨内成骨的影响，并利用生化信息学方法检测flnb对小鼠终板软骨细胞内相关信号通路蛋白的表达调控作用，以期初步阐明FLNB基因突变在休门氏病发病中的作用机制。

课题组基于前期休门氏病家系样本及测序结果，国际上率先开展休门氏后凸畸形患者 IPSCs 的培育及分化研究，发现患者IPSCs 向 BMSCs及软骨细胞系的分化及增殖中存在缺陷，且该缺陷可能导致休门氏后凸畸形的发生发展；同时在国际上首次构建FLNB c.4625T>C突变小鼠模型，确定纯合小鼠存在脊柱后凸的表型，并通过单细胞测序检测发现：相较于野生型小鼠，突变纯合小鼠的椎间盘及终板骨样本中富含有较多的中性粒细胞，且突变纯合小鼠中软骨细胞亚群存在显著差异。因此可以认为FLNB c.4625T>C突变可能导致局部免疫微环境的改变进而影响终板软骨细胞的增殖分化能力最终导致休门氏后凸畸形的出现。