ADAR1 的RNA编辑靶点预测和实验验证

RNA editing is an integral step in generating the diversity and plasticity of cellular RNA signatures. Most editing events convert A to I(G) (adenosine to inosine, which is translated as guanosine), and are catalyzed by the double-stranded RNA-specific ADAR family of proteins. Mammalian ADARs family has three closely related proteins ADAR1,2 and-3, whose functions in the various tissues they are expressed in are poorly understood. Dyschromatosis symmetrica hereditaria (DSH) is a rare autosomal dominant genodermatosis, it is caused by heterozygous mutation of ADAR1 gene. Its clinical symptoms are hyperpigmented and hypopigmented macules mostly on the dorsal aspects of the extremities. The ADAR1-mediated editing sites and molecular mechanism of why ADAR1 heterozygous mutation causes DSH is still unclear. Based on the RNA-seq of ADAR1 morphants and DSH patients with ADAR1 pathogenic mutations, we will develope algorithms to predict editing sites in dsRNA of any sequence, and provide a web-based application. Then we will varify the predicted results by transcriptome sequencing and MassARRAY technology in the skin of patient with different kind of causative mutations. This study will further elucidate the melacular mechanism of DSH and the function fo ADAR1.

ADAR介导的RNA腺苷脱氨基修饰是重要的翻译后调控机制，哺乳动物中已知有ADAR1、ADAR2和ADAR3三种ADARs，表达有明显的组织特异性，但它们在不同组织中的功能仍不清楚。遗传性对称性色素异常症（DSH）是一种少见的常染色体显性遗传性皮肤病,是ADAR1基因杂合突变所致，但目前ADAR1基因的靶位点和DSH的分子机制尚不明确。DSH以肢端对称分布的形状和大小不规则的色素沉着和色素减退网状斑为典型临床表现。结合前期斑马鱼研究数据，根据不同ADAR1突变类型的DSH患者皮肤组织的转录组测序和全基因组测序数据，本研究拟设计一种可以有效预测ADAR1编辑位点的新算法,并对预测的位点进行验证。通过挖掘ADAR1的靶基因,寻找ADAR1在皮肤中特异性编辑的位点，探索突变引起的异常表达和编辑基因，进而揭示DSH的发病机制。

RNA编辑是一种重要的基因转录后调控机制，主要编辑方式为腺嘌呤(A)脱氨基生成次黄嘌呤(I)。因为I在翻译过程中被识别为G，A→I编辑可以改变氨基酸编码、影响mRNA的剪接而增加编码蛋白质的多样性，还可能通过影响RNA的稳定性、编辑前体miRNA、lncRNA等机制调控基因的表达。A→I的编辑过程由RNA腺苷脱氨酶(ADARs)催化完成，ADARs家族重要成员包括ADAR1、ADAR2和ADAR3，其中ADAR3没有明显酶活性。基因转录后的RNA编辑是调控基因表达、维持正常生命活动不可或缺的调控机制。我们首先在ADAR1下调的斑马鱼模型中检测到1535个潜在的ADAR1编辑靶位点；其次，在健康志愿者的皮肤组织中检测到1956个RNA编辑位点，在ADAR1突变杂合子DSH患者皮肤组织中检测到199个编辑水平降低的位点；接着，基于被编辑位点序列保守性，二级结构等信息建立了一种有效的编辑位点预测方法；最后，我们还证明p150在DSH发病过程中起关键作用。本研究有助于了解ADAR1基因的功能，为揭示DSH的发病机制提供了重要线索。