rs10750836通过TPCN2基因调控参与自噬通路影响SLE发病的机制研究

Systemic lupus erythematosus (SLE) is a chronic autoimmune inflammatory disease characterized by T and B cells dysfunction, and production of antinuclear antibodies. Autophagy is an evolutionarily conserved lysosome-mediated catabolic process that maintains cellular homeostasis through the degradation of unwanted cytoplasmic constituents and recycling nutrients. Genome-wide association studies (GWAS) have linked polymorphisms in Atgs to SLE. Overactive autophagy have also confirmed in T and B cells of SLE model animals or patients. The applicant performed a large-scale SLE exome-wide association study in a Han Chinese population using a custom exome array, and found TPCN2 gene was associated with SLE (Ann Rheum Dis，2018). Moreover, the applicant found that the expression level of TPCN2 gene was reduced significantly in SLE patients; the novel intergenic variant rs10750836 exhibited gene promoter activity for TPCN2 and this novel SNP exhibited a cis-expression quantitative trait locus (cis-QTL) effect on the TPCN2. Considering that the overactive expression of TPCN2 gene can inhibit LC3-dependent autophagy (LAP) pathway, the applicant proposed the hypothesis that the risk allele of rs10750836 located in the promoter region reduces the expression of TPCN2 gene, and then over activates LAP in the pathogenesis of SLE. This study intends to elucidate the mechanism of rs10750836 regulating TPCN2 and explain how the TPCN2 gene takes part in the autophagy pathways associated with SLE by molecular biology and animal experiments.

系统性红斑狼疮（SLE）是一种主要以T、B淋巴细胞功能障碍，以及自身抗体形成为特征的自身免疫性疾病。自噬是进化上保守的溶酶体介导的分解代谢过程，通过解降不需要的细胞质成分和回收营养物质维持细胞稳态。全基因组关联研究已经发现自噬相关基因与SLE遗传风险相关。研究证实SLE模型动物或患者的T、B淋巴细胞中自噬活性增强。申请人在汉族人中进行SLE全外显子组关联研究（Ann Rheum Dis，2018）发现TPCN2与SLE易感性相关。TPCN2在SLE患者中表达显著降低，rs10750836对其有顺式调控作用，并位于基因的启动子区。有文献报道TPCN2表达增加，抑制LC3依赖的自噬。申请人提出猜想调控区的rs10750836风险等位基因下调TPCN2表达，过度激活吞噬作用参与SLE的发病。本研究拟通过分子生物学和动物实验，阐明rs10750836调控TPCN2参与自噬通路影响SLE发病的机制。

系统性红斑狼疮（SLE）是一种多器官受累的自身免疫病，具有疾病负担重，发病机制复杂的特点。长期以来，细胞凋亡和凋亡细胞清除效率低下被认为是SLE的重要发病机制之一。其中，细胞凋亡或程序性细胞死亡是调节细胞生长和死亡的关键机制，当其异常时常诱发自身免疫紊乱。TPCN2是电压门控离子通道超家族的成员，与包括SLE在内的多种疾病有关。申请人在汉族人中进行的SLE全外显子组关联研究发现，位于TPCN2的rs10750836变异位点可能与SLE易感性有关，本研究进一步发现该位点在免疫细胞中表现出对TPCN2基因表达的eQTL效应。课题组研究结果显示，TPCN2的表达水平在SLE患者中显著降低。因此，本研究通过构建shh细胞系，敲降THP1及Jurkat等免疫细胞的TPCN2基因表达，证实TPCN2缺陷通过调控PI3K/AKT/mTOR信号通路促进细胞凋亡增加和G2/M期阻滞，从而抑制细胞增殖，表明TPCN2可能是SLE的潜在保护因子。我们的研究结果为将TPCN2作为狼疮治疗的靶点提供了理论依据，同时为进一步研究狼疮机制提供了重要指导。