Role of Id genes during cardiac development

描述(由申请人提供)： 这项建议的目的是解决ID(分化抑制物)基因在发育过程中特定心脏分室中的作用。IDL、2和3在发育中的心外膜、心内膜和心内膜垫(ECs)中表达，但在心肌中不表达。Idl、Id2或Id3基因去除研究表明没有发育缺陷，但Idlld3、Idl Id2和Id21d3双突变胚胎在E13.5之前死亡。以不同的组合消融IDL-3不仅会导致心内膜和内皮细胞的心脏缺陷，还会导致心肌的缺陷，这表明各层之间存在交叉通讯。ID缺陷胚胎表现为小梁和室间隔受损，心肌壁变薄，流出道狭窄，心内膜排列紊乱，内皮细胞减少。注射LacZ标记的胚胎干细胞逆转了心脏的异常，挽救了Idlld3KO胚胎的胚胎致死性。IDKO胚胎中改变的心肌标志物在被拯救的心脏的突变细胞中恢复到正常。因此，ES来源的细胞能够以非细胞自主的方式逆转突变细胞中的基因表达谱。这些观察提出了重要的生物学问题：ID在心外膜、心内膜/EC和心肌中的作用是什么？ID的动作模式是否是非细胞自主的？哪些ID依赖的信号参与了心脏各层之间的串扰？为了回答这些问题，我们建议研究ID基因在成人获救嵌合体心脏中的作用(AIM I)，研究特定心室对ID基因的需求(AIM II)，并确定ID信号的关键介质(AIM III)。我们将使用小鼠模型来扩展对ES细胞进行的研究。此外，我们还将生成条件性KO和组织特异性转基因模型。一些实验将得到组织培养研究的补充。斯隆-凯特琳癌症研究所提供了开展该项目所需的适当环境，包括小鼠转基因、基因组学核心和组织学核心设施。长期目标是开发小鼠模型，以更好地了解发育控制基因在心脏形成中的作用，这些基因的突变如何导致先天性心脏病，以及如何通过注射胚胎干细胞来预防或改善这些异常。这些研究可能对先天性心脏病有重要意义。

DESCRIPTION (provided by applicant): The goal of this proposal is to address the role of the Id (inhibitor of differentiation) genes in specific cardiac compartments during development. Idl, 2 and 3 are expressed in the developing heart in the developing epicardium, endocardium and endocardial cushions (ECs), but not in the myocardium. Idl, Id2 or Id3 gene ablation studies revealed no developmental defects, but Idlld3, Idl Id2 and Id21d3 double mutant embryos die by E13.5. Ablation of Idl-3 in varying combinations resulted in cardiac defects not only in the endocardium and in the ECs, but also in the myocardium, suggesting cross-communication between layers. Id deficient embryos displayed impaired trabeculae and interventricular septum, thin myocardial wall, stenotic outflow tract, disorganized endocardium and hypocellular ECs. Injection of LacZ-marked Embryonic Stem (ES) cells reversed the cardiac abnormalities and rescued the embryonic lethality of the Idlld3 KO embryos. Altered myocardial markers in the Id KO embryos are restored to normal in the mutant cells of the rescued hearts. Thus, The ES-derived cells display the capacity to reverse gene expression profiles in mutant cells in a non-cell autonomous fashion. These observations raise important biological questions: What is the role of Id in the epicardium, endocardium/EC and in the myocardium? Is the Id mode of action non-cell autonomous? Which are the Id-dependent signals involved in the cross-talk between cardiac layers? Aiming to answer these questions we propose to study the role of Id genes in adult hearts of rescued chimeras (AIM I), to study the requirement for Id genes in specific cardiac compartments (AIM II), and to identify key mediators of Id signaling (AIM III). We will use murine models to extend the studies conducted with ES cells. Additionally, we will generate conditional KO and tissue-specific transgenic models. Some of the experiments will be complemented by tissue culture studies. The Sloan-Kettering Institute for Cancer Research provides the appropriate environment required to carry out this project, including the mouse transgenic, genomics core, and histology core facilities. The long term goals are to develop murine models to better understand the role of developmental control genes in cardiac formation, how mutations in those genes lead to congenital heart disease, and how these abnormalities could be prevented or ameliorated by embryonic stem cell injection. These studies may have important implications for congenital heart disease.