Male-Biased Aganglionic Megacolon in the TashT Mouse Line Due to Perturbation of Silencer Elements in a Large Gene Desert of Chromosome 10
Male-Biased Aganglionic Megacolon in the TashT Mouse Line Due to Perturbation of Silencer Elements in a Large Gene Desert of Chromosome 10
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DOI：
10.1371/journal.pgen.1005093
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发表时间：
2015-03-01
期刊：
影响因子：
4.5
通讯作者：
Pilon, Nicolas
中科院分区：
文献类型：
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作者：
Bergeron, Karl-F.;Cardinal, Tatiana;Pilon, Nicolas
神经嵴细胞（NCC）是一种短暂的迁移细胞群，可产生多种细胞类型，如肠神经系统（ENS）的神经元和胶质细胞。通过对影响小鼠NCC发育的基因座进行插入突变筛选，我们确定了一个名为TashT的品系，该品系以强烈的男性偏好方式显示部分渗透性无神经节细胞巨结肠表型。有趣的是，这种表型非常令人想起人类先天性巨结肠症，这是一种神经海绵状血管病，具有仍然无法解释的男性性别偏见。与巨结肠表型相反，结肠无神经节细胞症在纯合子TashT动物中几乎完全渗透。在巨结肠表达的性别偏见可以解释的事实，即男性ENS结束，平均而言，在一个“临界点”的最小的结肠神经节细胞病变，而女性ENS结束，平均而言，刚刚超过it. Detailed胚胎肠分析表明，在纯合子TashT动物的无神经节细胞病变是由于肠道NCC迁移较慢。TashT插入突变定位于含有多个高度保守元件的基因沙漠中，这些元件在报告基因测定中表现出抑制活性。RNA-seq分析和3C测定显示，TashT插入至少部分地导致非特征性基因Fam 162 b的NCC特异性抑制缓解;通过瞬时转基因独立证实的结果。来自纯合TashT胚胎的肠NCC的转录特征也以编码ENS形成的最重要的信号传导途径的成员-Gdnf/Ret和Edn 3/Ednrb-的基因的失调为特征，并且有趣的是，X连锁基因的特定子集的下调。总之，这项研究不仅允许识别Fam 162 b编码和调控序列作为新的候选基因座的先天性巨结肠病，但也提供了重要的新的见解，其男性性别偏见。
Neural crest cells (NCC) are a transient migratory cell population that generates diverse cell types such as neurons and glia of the enteric nervous system (ENS). Via an insertional mutation screen for loci affecting NCC development in mice, we identified one line-named TashT-that displays a partially penetrant aganglionic megacolon phenotype in a strong male-biased manner. Interestingly, this phenotype is highly reminiscent of human Hirschsprung's disease, a neurocristopathy with a still unexplained male sex bias. In contrast to the megacolon phenotype, colonic aganglionosis is almost fully penetrant in homozygous TashT animals. The sex bias in megacolon expressivity can be explained by the fact that the male ENS ends, on average, around a "tipping point" of minimal colonic ganglionosis while the female ENS ends, on average, just beyond it. Detailed analysis of embryonic intestines revealed that aganglionosis in homozygous TashT animals is due to slower migration of enteric NCC. The TashT insertional mutation is localized in a gene desert containing multiple highly conserved elements that exhibit repressive activity in reporter assays. RNA-seq analyses and 3C assays revealed that the TashT insertion results, at least in part, in NCC-specific relief of repression of the uncharacterized gene Fam162b; an outcome independently confirmed via transient transgenesis. The transcriptional signature of enteric NCC from homozygous TashT embryos is also characterized by the deregulation of genes encoding members of the most important signaling pathways for ENS formation-Gdnf/Ret and Edn3/Ednrb-and, intriguingly, the downregulation of specific subsets of X-linked genes. In conclusion, this study not only allowed the identification of Fam162b coding and regulatory sequences as novel candidate loci for Hirschsprung's disease but also provides important new insights into its male sex bias.