Developmental/Genetic Analysis of DiGeoge Models

描述(申请人提供)：我们的长期目标是利用小鼠模型从发育和遗传上确定DiGeorge/VCFS综合征(DGS/VCFS)的发病机制。22q111.2杂合性缺失是DGS影响许多组织的分子基础，这些组织的正常发育依赖于神经脊细胞。这种综合征的遗传和发育病因是复杂的。最近发现Tbx1(定位于22q11.21的T-box基因的小鼠同源基因)单倍性不足导致主动脉弓动脉异常发育，这表明Tbx1在DiGeorge综合征中起着关键作用。虽然大约90%的患者在22ql 1.2有常见的3Mb杂合子缺失，但相当数量的综合征患者有较小的缺失，在3Mb区域内不重叠。因此，很难简单地用单个基因的突变来解释这种综合征。我们最近的研究表明，位于3Mb缺失区的另一个22q11.21基因CRKL(CRK样)的缺失也可能与该综合征有关。CrkL(基因符号Crk1)的纯合缺失重现了一系列与DGS相似的神经脊缺陷。此外，我们最近注意到C57BL/6同源背景中CRK1的单倍性不足。为了深入了解DGS的病因以及先天性心脏缺陷的机制，我们提出了以下具体目标：1.确定CRK1胚胎心血管缺陷的发育机制。2.确定CRK1参与的遗传途径。为了解决这些目标，我们提出以下子目标：Subaim 1.1)测试假设，即CrkL对于心血管系统的正常神经脊贡献是必需的；Subaim 1.2)测试关于CrkL对于心脏神经峰衍生物的生长或生存是必需的假设；Subaim 2.1)确定CrkL对于其至关重要的遗传等级；Subaim 2.2)测试CrkL参与由Src家族激酶介导的信号通路的假设；Subaim 2.3)确定Crk1与Tbxl对于神经峰衍生物的正常发育所需的遗传交互作用。

DESCRIPTION (provided by applicant): Our long-term goal is to define the pathogenesis of DiGeorge/velocardiofacial syndrome (DGS/VCFS) developmentally and genetically using mouse models. Heterozygous deletions at 22ql 1.2 are the molecular basis of DGS affecting many tissues whose normal development depends on neural crest cells. The genetic and developmental etiology of this syndrome is complex. The recent discovery that haploinsufficiency of Tbxl (the mouse homologue of a T-box gene mapped at 22q11.21) causes abnormal development of aortic arch arteries suggests a critical role for TBX1 in DiGeorge syndrome. Although approximately 90% of the patients have a common 3 Mb heterozygous deletion at 22ql 1.2, a significant number of syndromic patients have smaller deletions that do not overlap within the 3 Mb region. It is therefore difficult to explain this syndrome simply by a mutation of a single gene. Our recent study suggests that deletion of another 22q11.21 gene, CRKL (CRK-Like), mapped within the 3 Mb deletion region may also contribute to this syndrome. Homozygous deletion of CrkL (gene symbol Crkl) recapitulates a wide range of neural crest defects that closely mimic DGS. Furthermore, we have recently noted that haploinsufficiency of Crkl in a C57BL/6 congenic background. To provide insight into the etiology of DGS as well as the mechanisms of congenital heart defects, we propose the following specific aims: 1. To determine the developmental mechanism of the cardiovascular defects in Crkl- embryos. 2. To determine the genetic pathways in which Crkl plays a role. To address these aims, we propose the following subaims: Subaim 1.1) To test the hypothesis that CrkL is required for proper neural crest contribution to the cardiovascular system; Subaim 1.2) To test the hypothesis that CrkL is essential for growth or survival of cardiac neural crest derivatives; Subaim 2.1) To determine the genetic hierarchy for which Crkl is essential; Subaim 2.2) To test the hypothesis that CrkL is involved in signaling pathways mediated by Src family kinases; Subaim 2.3) To determine the genetic interactions of Crkl with Tbxl for proper development of neural crest derivatives.