Retinoid-Related Genes in Diaphragm and Cardiac Development

描述（由申请人提供）：我们的长期目标是了解先天性膈疝（CDH）的分子基础-一种常见的危及生命的出生缺陷。然而，由于缺乏已知的CDH相关基因，对CDH发展背后的组织病理变化的理解不完整，以及缺乏基于细胞/培养的系统来研究隔膜发育，我们识别CDH发展中涉及的关键分子相互作用的能力受到阻碍。这些限制可以通过研究同样参与相关器官（如心脏）发育的cdh相关基因来最小化，这些器官更适合研究。由于高达40%的CDH患者也有心血管畸形（cvm），这些器官之间可能共享一些关键的发育程序/途径。在本研究中，我们将利用新的小鼠模型、基于细胞的系统和独特的人力资源，通过研究SOX7和gata4（位于染色体8p23.1上CDH/CVM最小缺失区域的两个类视黄醇应答转录因子）来确定这些共性。本提案的具体目标包括：1)确定与横膈膜中Sox7和Gata4破坏相关的组织病理学变化；2)确定Sox7在心脏发育中的作用；3)确定Sox7依赖的Gata4上调的分子基础，并确定Sox7在横膈膜和心脏发育中是否与Gata4基因相互作用；4)确定导致或易感CDH发展的类维生素a相关基因的有害变化。我们已经证明，部分Sox7小鼠出现了与Gata4小鼠相似的前侧CDH。我们将首先确定该模型中易患CDH的组织病理学变化，然后通过使用Nkx3-2 Cre有条件地破坏Sox7和Gata4在后膈中的表达，确定其在后膈中的作用。为了确定Sox7在心脏发育中的作用，我们将改变体外分化P19细胞中Sox7的表达，并使用Nkx2-5 Cre分析Sox7-/-胚胎和小鼠的体内心脏表型，其中Sox7在第一和第二心脏区表达被破坏。这些表型背后的分子变化将使用标准分子技术进行鉴定。我们还将确定SOX7与Gata4启动子的直接结合是否负责SOX7依赖于Gata4的向上调节。通过比较单杂合和双杂合小鼠中CDH和cvm的发生率和严重程度，我们还将确定Sox7是否与Gata4在体内发生遗传相互作用。为了确认它们在人类CDH中的个体作用，并发现新的基因型/表型相关性，我们将在CDH患者队列中确定SOX7、GATA4和其他两个类维生素a相关转录因子COUP-TFII和FOG2的有害变化。在短期内，这些研究将有助于我们了解隔膜和心脏中SOX7和GATA4调控的关键分子和生物学途径，这些途径的破坏导致CDH和cvm的发展。反过来，这可能会导致针对这些出生缺陷的新的治疗或预防策略的发展。

DESCRIPTION (provided by applicant): Our long-term goal is to understand the molecular basis of congenital diaphragmatic hernia (CDH)-a common life threatening birth defect. However, our ability to identify key molecular interactions involved in CDH development is hindered by a general paucity of known CDH-related genes, an incomplete understanding of the histopathologic changes that underlie CDH development and the lack of a cell based/culture based system in which to study diaphragm development. These limitations could be minimized by studying CDH-related genes that are also involved in the development of related organs, such as the heart, that are more amenable to study. Since up to 40% of individuals with CDH also have cardiovascular malformations (CVMs), it is likely that some key developmental programs/pathways are shared between these organs. In this proposal we will identify these commonalities by studying SOX7 and GATA4-two retinoid-responsive transcription factors located together in the CDH/CVM minimal deleted region on chromosome 8p23.1-using novel mouse models, cell based systems, and unique human resources. Specific aims for this proposal include: 1) identify the histopathologic changes associated with disruption of Sox7 and Gata4 in the diaphragm, 2) define the role of Sox7 in cardiac development, 3) identify the molecular basis of SOX7-dependent up regulation of Gata4 and determine if Sox7 interacts genetically with Gata4 in diaphragm and cardiac development and 4) identify deleterious changes in retinoid-related genes that cause or predispose to the development of CDH. We have shown that a portion of Sox7 mice develop anterior CDH similar to that seen in Gata4 mice. We will first determine the histopathologic changes that predispose to CDH in this model and then determine the role of Sox7 and Gata4 in the posterior diaphragm by conditionally disrupting their expression using an Nkx3-2 Cre. To define Sox7's role in heart development we will alter Sox7 expression in differentiating P19 cells in vitro and analyze the in vivo cardiac phenotype of Sox7-/- embryos and mice in which Sox7 expression has been disrupted in the first and second heart fields using an Nkx2-5 Cre. The molecular changes that underlie these phenotypes will then be identified using standard molecular techniques. We will also determine if direct binding of SOX7 to the Gata4 promoter is responsible for SOX7-dependent up regulation of Gata4. By comparing the incidence and severity of CDH and CVMs in single and double heterozygous mice, we will also determine if Sox7 interacts genetically with Gata4 in vivo. To confirm their individual roles in human CDH, and to discover novel genotype/phenotype correlations, we will identify deleterious changes in SOX7, GATA4 and two other retinoid-related transcription factors, COUP-TFII and FOG2, in a cohort of CDH patients. In the short term, these studies will help us to understand the key molecular and biological pathway regulated by SOX7 and GATA4 in both the diaphragm and heart whose disruption leads to development of CDH and CVMs. This, in turn, may lead to the development of novel therapeutic or preventative strategies for these birth defects. PUBLIC HEALTH RELEVANCE: SOX7 and GATA4 are two genes that are important for both diaphragm and heart development. These studies will help us understand how changes in SOX7 and GATA4 cause these life- threatening birth defects and what other genes may be involved. This knowledge may lead to the development of new ways to diagnose, prevent or treat these birth defects.