ADAR1 mediated regulation of neural crest-derived melanocytes and Schwann cell development.

We studied the physiological requirement of A-to-I RNA editing in neural crest cells. To this end, we generated mouse lines that undergo neural crest cell-specific deletion of Adar1 making use of the HtPAcre reporter. The mutants show global depigmentation and absence of myelin within the peripheral nerves. To assess global changes in gene regulation caused by conditional Adar1 deficiency in Schwann cells, a we performed transcriptomic analysis (RNA-seq) of sciatic nerves from independent samples from three control and three mutant animals at P4. The steady-state level of 3,009 mRNAs differed by at least two-fold in abundance between the two genotypes. Analysis of the 3,009 differentially-expressed mRNAs using the interferome database showed 75% of them to be within or associated with IFN type 1 or 2 signaling pathway. Interestingly, 34% of the RNA transcripts deregulated upon Adar1 invalidation are also deregulated upon nerve injury. Overall, our results suggest that Adar1 safeguards neural crest-derived cells from unwanted MDA5-mediated interferon production and chronic Interferon stimulated genes upregulation, with implications for the human diseases caused by ADAR1 mutations and neural crest development and linked-disorders. We performed transcriptomic analysis (RNA-seq) of sciatic nerves from independent samples from three control and three mutant animals at Post-natal day 4.我们研究了神经嵴细胞(neural crest cells)中A-to-I RNA编辑(A-to-I RNA editing)的生理需求。为此，我们利用HtPAcre报告基因(HtPAcre reporter)构建了可在神经嵴细胞中特异性敲除Adar1(Adar1)的小鼠品系。该突变体小鼠表现出全身性色素脱失，且外周神经(peripheral nerves)内无髓鞘形成。为探究雪旺细胞(Schwann cells)中条件性Adar1缺失所引发的基因调控全局变化，我们对出生后第4天(Post-natal day 4, P4)的3只对照组与3只突变体小鼠的坐骨神经(sciatic nerves)独立样本开展了转录组测序(RNA-seq)分析。两种基因型小鼠的3009个mRNA的稳态丰度差异至少达2倍。利用干扰素组数据库(interferome database)对这3009个差异表达mRNA(differentially-expressed mRNAs)进行分析后发现，其中75%的基因属于或与I型、II型干扰素(IFN)信号通路相关。值得注意的是，Adar1功能失活后表达失调的RNA转录本中，有34%同样在神经损伤后出现表达异常。综上，本研究结果表明，Adar1可保护神经嵴来源细胞(neural crest-derived cells)免受异常MDA5(MDA5)介导的干扰素产生以及慢性干扰素刺激基因(Interferon stimulated genes)上调，该发现对ADAR1突变相关人类疾病、神经嵴发育及相关病症具有参考意义。我们对出生后第4天的3只对照组与3只突变体小鼠的坐骨神经独立样本开展了转录组测序(RNA-seq)分析。