一家族性单基因遗传自身免疫病致病基因SOX13的发现及功能分析

自身免疫病具有较高的发生率，分离其致病基因对于了解疾病的发生机制及防治具有重要的意义。课题组前期利用全外显子组测序对一单基因遗传的自身免疫病大家系进行分析，过滤筛选后发现SOX13 p.S453I 错义突变在家系内与表型共分离且在进化中高度保守，生物信息学分析证实该变异影响了蛋白功能，提示SOX13基因突变导致了自身免疫病。为探索该变异的致病性及SOX13导致疾病发生的分子机制，课题组利用基因打靶技术构建Sox13 p.S453I 的基因敲入与敲除小鼠模型，通过对Knock in小鼠注射II型胶原（CII）诱导产生风湿性关节炎或注射pristane诱导产生系统性红斑狼疮等表型分析证实突变的致病性，分析敲除小鼠γδT等细胞的变化，通过ChIP-Seq、免疫荧光、流式细胞术等技术分析SOX13致病的分子机制，为揭示SOX13在自身免疫病发生的分子机制进行探索。

In the preliminary study, we collected several families and sporadic cases with Systemic lupus erythematosus, rheumatoid arthritis. We performed whole exome sequencing in one multi-generation family in which 8 family members affected with Systemic lupus erythematosus, rheumatoid arthritis. After filtering with ExAC, 1000 genomes,ESP6500 and gnomAD, then conducted prioritization analysis, a candidate variant p.S453I in SOX13 gene was identified in the family. After Sanger sequencing all the family members, we found that this missense variant co-segregate with the phenotype in the family and is conservative across different species. PolyPhen-2,SIFT and Mutationtaster were used to predict the possible pathogenic effect of the variant. The bioinformatic analysis results revealed the substitution p.S453I was predicted to be likely detrimental to protein function. All the results suggested that variant p.S453I in SOX13 might play an critical role in the pathogenesis of autoimmune disease. But the detailed mechanisms remained unclear..In this proposed project, we aimed to confirmed its pathogenic role by 1) screening more disease families and sporadic cases to find more mutations in the SOX13 gene to confirm its disease-causative role. 2) in vitro studies such as ChIP-Seq and CoIP to provide more functional supportive clues for the variant, 3) phenotype assay for the knock-in mouse model to investigate the pathophysiological effect of Sox13 on autoimmune diseases . In addition, in vivo and in vitro functional studies of identified disease-causing genes will be carried out to investigate their critical roles in the pathogenesis of rheumatic diseases. Identification of more genes implicated in the autoimmune diseases will provide us a better understanding of the molecular pathology and help find potential treatments.