CSX, CARDIAC SPECIFIC HOMEBOX GENE

本提案的总体目标是促进对 导致心肌发育的遗传信号。遗传 导致骨骼肌分化的计划已经很好地 描述，并依赖于MyoD家族的转录因子。 导致心肌分化的事件顺序仍然是 尽管心肌和骨骼肌表达 重叠的肌肉特异性基因我们假设转录 这些因素将引导心肌发育，类似于MyoD 家族在骨骼肌分化中的作用。同源异型盒基因是 可能与心肌发育有关，因为它们在心肌发育中起着重要作用。 在多个物种的中胚层发育中起着重要作用。一 果蝇同源异型盒基因tinman在早期心脏病中的作用 由于纯合的tinman无效突变体不会发展成 背部血管，果蝇心脏类似物。的鼠同源物 锡人Csx是在我赞助人的实验室里克隆的初步分析 表明在其他细胞发育之前的小鼠心脏发育早期表达 表达肌肉特异性基因。此外，虽然纯合子Csx 裸小鼠确实发育了心管，心脏形态学清楚地 不正常. Csx的突变或功能丧失似乎从根本上 改变心肌发育和心脏形态。我们 目的是表征Csx表达的控制及其在 通过鉴定完整的基因组结构， 包括Csx启动子区。在体外和体内，我们将 开始定义参与Csx表达的调控元件。 Csx在转基因小鼠中的过表达将允许进一步分析 Csx表达扰动的影响。我们亦会研究 人类同源基因hCsx的表达模式和染色体定位 小鼠Csx。作为一名儿科心脏病专家，我对 在导致心脏正常发育的遗传途径中。我开始 在我的奖学金培训期间进行分子生物学研究， 致力于在该地区从事独立的调查工作 心脏的发育。申办者，Seigo Izumo医生，心脏科主任 在密歇根大学，他的工作是公认的， 转录因子和心脏基因表达。出云博士会提供 科学的指导和训练来实现我的目标他 实验室提供必要的人员和设施， 分子生物学的研究训练。此外。大学 密歇根州是一个活跃的分子生物学研究中心， 特别是在将分子进展与医学实践联系起来方面， 提供了一个激励学习的研究环境。这是一 我希望能够获得更多研究的环境 技能，以最终提高对发病机制的理解， 先天性心脏病

The overall goal of this proposal is to advance the understanding of the genetic signals that lead to development of cardiac muscle. The genetic program leading to skeletal muscle differentiation has been well described, and is dependent on the MyoD family of transcription factors. The sequence of events leading to cardiac muscle differentiation remains largely unknown, though cardiac muscle and skeletal muscle express overlapping muscle-specific genes. We hypothesize that transcription factors will guide cardiac muscle development, similar to the MyoD family's role in skeletal muscle differentiation. The homeobox genes are likely involved in cardiac muscle development, since they play a prominent role in mesodermal development in multiple species. A Drosophila homeobox gene, tinman, is essential for early cardiac development since a homozygous tinman null mutant does not develop a dorsal vessel, the Drosophila heart analogue. The murine homologue of tinman, Csx, was cloned in my sponsor's laboratory. Preliminary analysis indicates expression during early murine cardiac development before other muscle-specific genes are expressed. In addition, although homozygous Csx null mice do develop a heart tube, the cardiac morphology is clearly abnormal. Mutations in or loss of function of Csx seem to fundamentally alter development of cardiac muscle and cardiac morphology as well. Our goal is to characterize the control of expression of Csx and its role in cardiac myocyte development by identifying the complete genomic structure of Csx, including the Csx promoter region. In vitro and in vivo, we will begin to define the regulatory elements involved in Csx expression. Overexpression of Csx in transgenic mice will allow further analysis of the effect of perturbations of Csx expression. We will also examine the expression pattern and chromosomal location of hCsx, the human homologue of murine Csx. As a pediatric cardiologist, I have a particular interest in the genetic pathways that lead to normal cardiac development. I began molecular biology research during my fellowship training, and am dedicated to pursuing an independent investigative career within the area of cardiac development. The sponsor, Dr. Seigo Izumo, Chief of Cardiology at the University of Michigan, is recognized for his work on transcription factors and cardiac gene expression. Dr. Izumo will provide the scientific guidance and training required to achieve my goal. His laboratory provides the necessary personnel and facilities to obtain research training in molecular biology. Furthermore. the University of Michigan is an active center for molecular biology research, in particular in relating molecular advances to medical practice, and provides a stimulating research environment in which to learn. It is an environment in which I expect to be able to acquire additional research skills to ultimately improve the understanding of the pathogenesis of congenital heart disease.