Cellular and Molecular Mechanisms of Left Ventricular Growth and Morphogenesis

项目摘要/摘要 先天性心脏病(CHD)是最常见的出生缺陷。在各种CHD中，单心室 由心室形态发生改变引起的表型临床预后最差，包括 三尖瓣闭锁(OMIM#605067)、肺闭锁(OMIM#265150)和左心发育不良综合征 (HLHS；OMIM#241550,614435)。单心室心脏呈现一系列回路，从而使全身 右心室和肺动脉的静脉回流与肺静脉血相结合 回到左心室，再回到身体，这与生存是不相容的。目前，有一个贫穷的 了解多种形式单纯性骨质疏松症的分子机制和细胞病因学 心室型冠心病。 人类心脏转录因子基因NKX2.5和HAND1在HLHS中被观察到突变 病人。建模和对可能的HLHS表型的研究一直局限于当前的系统性和 鉴于广泛的表达结构域，NKX2.5和Hand1的条件敲除会导致胚胎死亡 可用CRE线路的数量。由于缺乏受限的左心室CRE驱动程序，这类调查无法进行。Hand1为 在左心室的初级心场心肌中表达。我们已经分离出了增强剂 调节Hand1的左心室表达并利用它产生一个新的左心室特异性CRE驱动程序 通过它可以询问驱动左心室形态发生的细胞和分子机制 意识到了。我们的实验计划是去除发育中的Hand1左心室系细胞 胚胎心脏，有条件地删除左室心肌中特异的NKX2.5，并验证 从24名无血缘关系的患者中分离出HAND1中的人类突变，发现其是HLHS的病因。这 研究Hand1系心肌在心脏发生中的作用将有助于细胞病因学的研究 单心室表型和控制室成熟的分子程序，因此 扩大对与人类疾病相关的心室形态发生的理解。 相关性： 导致单心室表型的CHDS的临床结果最差。因此，获得一个 了解导致单心室心脏的CHDS的病因和分子机制 每年有可能使数以千计的儿科患者受益。Hand1谱系在人类进化中起着关键作用 单心室表型的发生及其细胞和分子机制的研究 研究不足的心肌人群将对发展冠心病的非手术治疗大有裨益 病人。

PROJECT SUMMARY/ABSTRACT Congenital heart disease (CHD) is the most common birth defect. Among various CHDs, single ventricle phenotypes resulting from altered ventricular morphogenesis have the poorest clinical prognoses and include Tricuspid Atresia (OMIM# 605067), Pulmonary Atresia (OMIM# 265150), and Hypoplastic Left Heart Syndrome (HLHS; OMIM# 241550, 614435). The single ventricle heart presents with a series circuit such that systemic venous return to the right ventricle and pulmonary arteries combined with the flow from the pulmonary venous return into the left ventricle and out to the body is incompatible with survival. Currently, there is a poor understanding of the molecular mechanisms and cellular etiology causative of the many forms of single ventricle CHD. Human mutations in the cardiac transcription factor genes NKX2.5 and HAND1 have been observed in HLHS patients. Modeling and thus the study of possible HLHS phenotypes have been limited as current systemic and conditional knockouts of Nkx2.5 and Hand1 results in embryonic lethality given the broad expression domains of available Cre lines. The lack of a restricted left ventricle Cre driver prohibits such investigations. Hand1 is expressed within the primary heart field myocardium of the left ventricle. We have isolated the enhancer that regulates Hand1 left ventricular expression and used it to generate a novel left ventricular-specific Cre driver with which interrogation of the cellular and molecular mechanism driving left ventricular morphogenesis can be realized. Our experimental plan is to ablate the Hand1 left ventricular lineage cells from the developing embryonic heart, conditionally delete Nkx2.5 specifically within the left ventricular myocardium, and validate an identified human mutation in HAND1 isolated from 24 unrelated patients as being causative of HLHS. This study of the role that Hand1-lineage myocardium plays during cardiogenesis will shed light on the cell etiology of single ventricle phenotypes and on the molecular programs controlling ventricular maturation, thus expanding the understanding of ventricular morphogenesis as it relates to human disease. Relevance: CHDs resulting in single ventricle phenotypes have the poorest clinical outcomes. Thus, gaining an understanding of the etiology and molecular mechanisms that cause CHDs resulting in a single ventricle heart has the potential to benefit thousands of pediatric patients annually. The Hand1-lineage plays a key role in the genesis of single ventricle phenotypes and gaining insight into the cellular and molecular mechanism of this understudied myocardial population will have a great benefit to developing non-surgical treatments for CHD patients.