ANALYSIS OF DOMINANT MEGACOLON-- MODEL FOR HIRSCHSPRUNG

Sox10转录因子突变杂合子的动物在神经脊发育中表现出多种缺陷，包括皮肤中黑素细胞数量减少，结肠中缺乏肌间神经节，并可能与耳聋有关。同卵动物在子宫中死亡，整个周围神经系统都有广泛的缺陷。先天性巨结肠症是一种人类先天性疾病，也表现为直肠无神经节细胞增多症，可与色素减退有关，并由Sox10突变引起。因此，Sox10小鼠和其他神经脊突变小鼠一样，是这种疾病的小鼠模型。我们发现，Sox10缺陷干扰了早期神经脊基因的表达，MITF、DCT和EDNRB将Sox10基因置于神经脊发育的早期途径。我们正在使用额外的标记和谱系定向的基因转移来确定Sox10的作用模式及其对下游靶点的影响。Sox10在先天性巨结肠症和其他神经脊相关疾病中的作用将被探索。我们已经证明Sox10直接控制MITF和DCT的表达。我们已经证明，对靶基因的影响在自然界中是半显性的。我们制造了过表达Sxo10的转基因小鼠，以分析其对神经脊干细胞发育的影响。 我们还建立了一个系统，将基因重新添加到神经脊干细胞中，以弥补遗传缺陷。我们将使用这个系统来测试Sox10和它的目标基因之间的层次关系。我们已经证明，我们可以使用这个系统来纠正Sox10的体外缺陷。我们已经生成了矢量，以使这一过程非常有效。 我们还建立了一个全基因组突变程序来鉴定Sox10的遗传互作因子。到目前为止，我们已经确定了两个易感基因座。这些基因可能成为人类修饰性基因座，也可能成为神经脊发育途径的有趣贡献者。此外，我们还开发了一种隐性突变筛选，以确定这一途径中的其他成员，迄今已发现两个新的突变。我们正在努力识别这种基因，并寻找相关的人类疾病。

Animals heterozygous for mutants in the SOX10 transcription factor exhibit multiple defects in neural crest development including reduced numbers of melanocytes in the skin, an absence of myenteric ganglion in the colon and can be associated with deafness. Homozgous animals die in utero and there is extensive defects in the entire peripheral nervous system. A human congenital disorder, Hirschsprung disease also exhibits rectocolic aganglionosis and can be associated with hypopigmentation and casued by SOX10 mutations. Thus SOX10 mice, as well as the other neural crest mutant mice, serve as mouse models for this disease. We have found that the SOX10 defects disrupt expression of early neural crest genes, MITF, DCT and EDNRB placing the SOX10 gene early in the neural crest development pathway. We are using additional markers and lineage directed gene transfer to determine the mode of action of SOX10 and its effects on downstream targets. Investigation of the involvement of SOX10 in Hirschsprung disease and other neural crest related disorders will be explored.We have demonstrated that SOX10 directly controls the expression of MITF and DCT. We have shown that the effect on target genes is semindomnant in nature. We have made transgenic mice that overexpress Sxo10 to analyze its effects on neural crest stem cell development. We have also established a system for adding genes back to neural crest stem cells in order to complement genetic defects. We will use this system to test hierarchial relationships between SOX10 and its target genes. We have demonstrated that we can use this system to correct SOX10 defects in vitro. We have generated vectors to make this very efficient. We have also established a whole genome mutagenesis program to identifying SOX10 genetic interaction factors. We have identified two susceptibility loci to date. These may become human modifier loci and interesting contributors to neural crest developmental pathways. In addition we have developed a recessive mutagenesis screen to identify additional players in this pathway with two novel mutations identified to date. We are working to identify the gene and look for associated human diseases.