CSX, CARDIAC SPECIFIC HOMEBOX GENE

这项建议的总体目标是促进对 导致心肌发育的遗传信号。基因 导致骨骼肌分化的计划一直很好 描述并依赖于MyoD转录因子家族。 导致心肌分化的事件顺序仍然存在 很大程度上未知，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 因子将引导心肌发育，类似于MyoD 家族在骨骼肌分化中的作用。同源盒基因是 可能与心肌发育有关，因为它们扮演着一个 在多种物种的中胚层发育中起着重要作用。一个 果蝇同源框基因tinman是早期心脏发育所必需的 由于纯合子马口铁缺失突变体不会产生 背部血管，果蝇心脏的类似物。小鼠的同源基因 Tinman，CSX，是在我的赞助商的实验室克隆的。初步分析 提示在小鼠心脏发育早期表达先于其他 肌肉特异性基因被表达出来。此外，尽管CSX纯合子 空白鼠确实发育出心管，心脏形态明显 不正常。CSX基因突变或功能丧失似乎从根本上 改变心肌的发育和心脏的形态。我们的 目的是表征CSX的表达调控及其在血管内皮细胞中的作用。 通过鉴定完整的基因组结构实现心肌细胞的发育 包括CSX启动子区域。在体外和体内，我们将 开始定义CSX表达所涉及的调控元件。 在转基因小鼠中过表达CSX将使进一步分析 CSX基因表达的扰动效应。我们还将研究 人类同源基因hCsx的表达模式和染色体定位 小鼠的CSX。作为一名儿科心脏病专家，我特别感兴趣 在导致心脏正常发育的遗传途径中。我开始 在我的研究员培训期间进行了分子生物学研究，我 致力于在该地区从事独立的调查工作 心脏发育的影响。发起人，出云医生，心脏病首席 在密歇根大学，因其在 转录因子与心脏基因表达。出云博士将提供 实现我的目标所需的科学指导和训练。他的 实验室提供必要的人员和设施以获得 分子生物学方面的研究培训。更重要的是。伊利诺伊大学 密歇根是一个活跃的分子生物学研究中心， 特别是在将分子进步与医学实践联系起来方面，以及 提供了一个激励学习的研究环境。这是一个 我希望能够获得更多研究的环境 最终提高对心绞痛发病机制的认识的技巧 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.