CLCN7基因剪切位点杂合突变c.1883+2T>A导致恶性骨硬化症的机制研究

Osteopetrosis is a hereditary disease characterized by elevated bone density as a result of osteoclast deficiency or dysfunction. CLCN7 is the most common pathogenic gene, its clinical manifestations are widely heterogeneous, ranged from asymptomatic to lethal phenotype as anemia, infection, hepatosplenomegaly and bone marrow failure. Stem cell transplantation is the only treatment of malignant osteopetrosis. We found a malignant osteopetrosis family, the proband who received stem cell transplantation now live with a normal life. By whole exome sequencing and verification in family members, we focus on a heterozygous mutations c.1883+2T> A in intron 20 of CLCN7. So far, there are no reports of osteopetrosis caused by the heterozygous splice mutation at home and abroad, and its pathogenesis is not clear. Therefore, we intend to carry out functional studies in vitro, and construct CLCN7 mutant knock-in mice model, investigate the effects of mutations on osteoclasts from cell and molecule and the overall level, which is expected to clarify the pathogenic mechanism of malignant osteopetrosis, and lay the foundation for the treatment of drug targets.

骨硬化症是一种因破骨细胞缺乏或功能障碍导致的以骨密度升高为主要表现的遗传性疾病。CLCN7基因突变导致的骨硬化症最为常见，其临床表现具有广泛异质性，从无症状到贫血、感染、肝脾肿大、骨髓衰竭等致死性表型。干细胞移植是治疗恶性骨硬化症的唯一方法。我们发现一恶性骨硬化症家系，先证者接受干细胞移植后恢复健康，通过对先证者颊粘膜基因进行全外显子组测序及家系内成员验证，发现其携带CLCN7基因Intron20剪切位点杂合突变c.1883+2T>A。迄今，国内外尚无该杂合剪切突变导致骨硬化症的报道，其致病机制未明。因此，本课题拟通过体外功能试验，并构建CLCN7突变敲入小鼠模型，从细胞、分子和整体水平明确该突变对于破骨细胞的影响及骨硬化症发病中确切机制。本项目有望阐明剪切突变导致恶性骨硬化症的分子机制，以及为治疗药物靶点提供更多实验依据。

骨硬化症是一种因破骨细胞缺乏或功能障碍导致的以骨密度升高为主要表现的遗传性疾病。CLCN7基因突变导致的骨硬化症最为常见，其临床表现具有广泛异质性，我们发现一恶性骨硬化症家系，先证者接受干细胞移植后恢复健康，通过对先证者颊粘膜基因进行全外显子组测序及家系内成员验证，发现其携带CLCN7基因Intron20剪切位点杂合突变c.1883+2T>A。本课题拟通过构建携带目的和野生型基因重组质粒，并转染小鼠RAW264.7细胞，诱导其生成破骨细胞，将上述细胞于骨片上培养结果发现与野生型相比，携带突变基因的未观察到骨陷窝形成，提示该剪切位点突变可以通过降低破骨细胞功能导致恶性骨硬化症发生。我们的研究拓宽了CLCN7基因突变导致恶性骨硬化症的突变谱。