Comparative Genetics of the DiGeorge Syndrome Gene TBX1

描述（由申请人提供）：Velo心脏面部综合征和DiGeorge综合征（VCFS/DGS）是由单倍功能不全引起的最常见的人类发育障碍。多数患者为半合子，人22q11染色体缺失3mb。VCFS/DGS患者在神经嵴衍生的组织和器官系统中存在许多异常。这些包括面部畸形、心血管缺陷、免疫系统缺陷和许多其他缺陷。使用小鼠作为模型系统，pi已经能够证明Tbx1（一种位于缺失区间的基因）过表达或表达减少的小鼠在VCFS/DGS患者中受影响的许多器官系统中存在缺陷。TBX1编码一种对正常神经嵴发育至关重要的转录因子。虽然关于TBX1的作用机制的信息正在出现，但尚未有系统的工作来确定TBX1的作用途径和网络。私人党提议这样做。TBX1在进化过程中是高度保守的，该基因在斑马鱼（称为van gogh (vgo)）中的突变产生的表型与VCFS/DGS患者相似。基于这些结果，pi现在提出对斑马鱼和小鼠的TBX1通路和网络进行比较遗传学分析。他们建议使用正常和突变斑马鱼和小鼠胚胎在适当发育阶段的基因表达谱来发现由于TBX1蛋白减少或缺乏而改变表达模式的基因。他们将使用全载原位杂交方法来检查斑马鱼中大量这些基因的时空表达模式。还将在Tbx1突变斑马鱼和小鼠中检查一个子集。表达模式与TBX1或在适当的细胞和组织中相匹配的基因将在斑马鱼中通过过表达和基于morpholino的敲除进行遗传分析。如果有这些基因中的一些突变体，将单独检查它们，并与TBX1突变体结合检查。在某些情况下，pi将在小鼠中产生零和条件突变等位基因，以检查它们在发育中的作用。结合使用斑马鱼和小鼠以及高通量遗传和基因组方法，有望提供有关TBX1运作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.