Neuregulin 1 type III reduces severity in a mouse model of Congenital Hypomyelination Neuropathy. Mus musculus

Purpose: We hypothesised that neuregulin 1 type III would reverse CHN. Using a faithful mouse model of CHN, we rescued the myelination defects by activation of Nrg1 type III. Unexpectedly, rescue did not depend on upregulation of Egr2 or major myelin genes. Therefore we asked whether we could identify any transcriptomic signature of the canonical pathways downstream of Nrg1 type III that could explain the increase in myelination in the sciatic nerve. Methods: Sciatic nerve mRNA profiles of 30-day-old wild-type (WT), P0 mutant (Q215X/+), trangenic HA-NRG1 type III, and HA-NRG1 type III:Q215X mice were generated by deep sequencing, in duplicate, using Illumina HiSeq2500 . The sequence reads that passed quality filters were aligned to the mouse reference genome (mm10) with the transcript annotation (UCSC mm10 annotation download from TopHat website) using TopHat (v2.0.9). Quantification for the gene expression and differential expression analysis were done by the software Cufflinks (v2.2.0). Results: A comprehensive transcriptomic analysis of signals downstream of neuregulin 1 type III in rescued CHN nerves revealed imbalanced activation of MAPK/ERK signals and minor myelin genes, such as Pmp2 and Omg. Conclusions: Our findings demonstrate that although augmented Nrg1 type III activity modifies the composition of myelin, it still promotes thicker myelin and ameliorates nerve conduction velocity in a mouse model of CHN. Controlled increase of Nrg1 type III activity may be a therapeutic strategy in some hypomyelinating neuropathies. Overall design: Sciatic nerve mRNA profiles of 30-day-old wild-type (WT), P0 mutant (Q215X/+), trangenic HA-NRG1 type III, and HA-NRG1 type III:Q215X mice were generated by deep sequencing, in duplicate, using Illumina HiSeq2500

研究目的：我们提出假说，Ⅲ型神经调节蛋白1（neuregulin 1 type III）可逆转先天性低髓鞘性神经病（CHN）。借助精准构建的CHN小鼠模型，我们通过激活Ⅲ型神经调节蛋白1（Nrg1 type III）修复了髓鞘形成缺陷。出乎意料的是，该修复效应并不依赖于早期生长应答因子2（Egr2）或主要髓鞘相关基因的上调表达。因此，我们试图探寻Ⅲ型神经调节蛋白1下游经典通路的转录组特征，以解释坐骨神经中髓鞘形成增强的机制。实验方法：采用Illumina HiSeq2500测序平台，对30日龄野生型（WT）、P0突变型（Q215X/+）、转基因HA-Ⅲ型神经调节蛋白1（HA-NRG1 type III）以及HA-NRG1 type III:Q215X小鼠的坐骨神经进行mRNA转录组深度测序，每组设置2次生物学重复。将通过质量过滤的测序读段，结合转录组注释信息（从TopHat网站下载的UCSC mm10注释文件），利用TopHat（v2.0.9）比对至小鼠参考基因组mm10。基因表达定量及差异表达分析采用Cufflinks（v2.2.0）软件完成。研究结果：对修复后的CHN小鼠坐骨神经中Ⅲ型神经调节蛋白1下游信号进行全面转录组分析后发现，MAPK/ERK（丝裂原活化蛋白激酶/细胞外调节蛋白激酶）信号通路与周围髓鞘蛋白2（Pmp2）、少突胶质细胞髓鞘糖蛋白（Omg）等次要髓鞘相关基因的激活失衡。研究结论：本研究结果表明，尽管增强的Ⅲ型神经调节蛋白1活性会改变髓鞘的组成，但仍可促进髓鞘增厚，并改善CHN小鼠模型的神经传导速度。对Ⅲ型神经调节蛋白1活性进行可控性上调，或可成为部分低髓鞘性神经病的治疗策略。实验整体设计：采用Illumina HiSeq2500测序平台，对30日龄野生型（WT）、P0突变型（Q215X/+）、转基因HA-Ⅲ型神经调节蛋白1（HA-NRG1 type III）以及HA-NRG1 type III:Q215X小鼠的坐骨神经进行mRNA转录组深度测序，每组设置2次生物学重复。