Comparative Genetics of the DiGeorge Syndrome Gene TBX1

描述(申请人提供)：Velo心面部综合征和DiGeorge综合征(VCFS/DGS)是最常见的人类发育障碍，由单倍体功能不全引起。大多数患者为人类染色体22q11上3Mb缺失的半合子。VCFS/DGS患者在源自神经脊的组织和器官系统中有许多异常。这些疾病包括面部畸形、心血管缺陷、免疫系统缺陷等。使用小鼠作为模型系统，PI已经能够表明，位于缺失区间的TBX1基因过度表达或降低表达的小鼠，在VCFS/DGS患者的许多器官系统中存在缺陷。TBX1编码一种转录因子，对正常的神经脊发育至关重要。尽管关于TBX1作用机制的信息正在涌现，但还没有开展系统的努力来确定TBX1在其中发挥作用的途径和网络。私人投资督察建议这样做。TBX1基因在进化过程中高度保守，斑马鱼中该基因的突变被命名为梵高(VGo)，产生的表型与VCFS/DGS患者中看到的表型相似。基于这些结果，PI现在建议对斑马鱼和老鼠中的TBX1途径和网络进行比较遗传学分析。他们建议在适当的发育阶段使用正常和突变斑马鱼和小鼠胚胎的基因表达谱，以发现其表达模式因TBX1蛋白减少或缺失而改变的基因。他们将使用整体原位杂交方法来检测斑马鱼中大量这些基因表达的时空模式。一个子集也将在TBX1突变斑马鱼和小鼠身上进行检查。在斑马鱼中，表达模式与TBX1匹配的基因或在适当的细胞和组织中的基因将通过过度表达和基于吗啉的敲除进行遗传分析。如果这些基因中的一些突变是可用的，它们将被单独检查，并与TBX1突变一起进行检查。在某些情况下，PI将在小鼠身上产生零和条件突变等位基因，以检查它们在发育中的作用。斑马鱼和老鼠的使用与高通量的遗传和基因组方法相结合，有望提供关于TBX1运行的途径和网络的丰富信息。

DESCRIPTION (provided by applicant): Velo cardio facial syndrome and DiGeorge syndrome (VCFS/DGS) are the most common human developmental disorders that result from haploinsufficiency. Most of the patients are hemizygous for 3 Mb deletion on human chromosome 22q11. Patients with VCFS/DGS have a number of abnormalities in tissues and organ systems that are derived from the neural crest. These include facial dysmorphology, cardiovascular defects, immune system defects and many others. Using the mouse as a model system the PIs have been able to show that mice that either overexpress or have reduced expression of Tbx1, a gene located in the deleted interval, have defects in many of the organs systems affected in VCFS/DGS patients. TBX1 encodes a transcription factor that is critical for normal neural crest development. Although information about the mechanisms of action of TBX1 is emerging, no systematic efforts to identify the pathways and networks in which TBX1 acts have been undertaken. The PIs propose to do so. TBX1 is highly conserved during evolution and mutations of this gene in the zebrafish, designated van gogh (vgo), develop phenotypes that are similar to those seen in VCFS/DGS patients. Based on these results, the PIs now propose a comparative genetics analysis of the TBX1 pathways and networks in zebrafish and mice. They propose to use gene expression profiling of normal and mutant zebrafish and mouse embryos at the appropriate developmental stages to discover genes whose expression patterns are altered as a result of reduction or absence of TBX1 protein. They will use whole mount in situ hybridization methods to examine the spatiotemporal patterns of expression of a large number of these genes in zebrafish. A subset will also be examined in Tbx1 mutant zebrafish and mice. Genes whose expression patterns match that of TBX1 or in appropriate cells and tissues will be subjected to genetic analysis in zebrafish through overexpression and morpholino-based knock-downs. If mutants for some of these genes are available, they will be examined alone and in combination with TBX1 mutants. In some cases the PIs will generate null and conditional mutant alleles in mice to examine their role in development. The combination of the use of zebrafish and mouse together with high throughput genetic and genomic approaches promise to provide rich information about the pathways and networks in which TBX1 operates.