A Nuclear Receptor COUP-TFII in Cardiovascular Function

描述（由申请方提供）：COUP-TFII是一种孤儿核受体，属于类固醇受体超家族。在小鼠中消融COUP-TFII导致由于血管生成和心脏发育缺陷的早期胚胎死亡。为了进一步了解COUP-TFII在血管和心脏发育中的生物学功能，产生LacZ敲入和floxed COUP-TFII小鼠。LacZ基因敲入小鼠的X-Gal染色显示静脉内皮中的COUP-TFII高表达，但动脉中没有。此外，嵌合体分析表明，COUP-TFII在静脉内皮细胞中发挥细胞自主功能，但在动脉中不起作用。这些研究首次表明COUP-TFII是一种重要的静脉识别转录因子。在COUP-TFII基因座中插入loXP位点减少了COUP-TFII的表达，使COUP-TFII flox/-突变体在遗传上亚纯型。这些亚型突变体表现出先天性心脏病患者常见的房室间隔缺损（AVSD）。COUP-TFII无效突变体所显示的心房畸形与由亚型突变体引起的AVSD一起表明COUP-TFII在心脏发生中起关键作用。心脏缺陷是血管缺陷的固有缺陷还是继发缺陷目前尚不清楚。正常的心脏发育需要内皮细胞和心肌细胞之间的相互作用。COUP-TFII调节的靶细胞是内皮细胞还是心肌细胞还不清楚。为了阐明COUP-TFII在维持静脉特性和心脏发育中的作用，提出了两个具体目标。在目的1中，我们将使用COUP-TFII在内皮细胞中的功能获得和功能丧失来检查COUP-TFII在维持动静脉特性中的作用。此外，我们将使用DMA芯片微阵列分析，以确定新的下游目标和信号通路，在动静脉决策的COUP-TFII调节。在目标2中，我们将使用亚型突变体和内皮和心肌条件性COUP-TFII敲除来研究COUP-TFII在心脏发育中的作用。这项研究将使我们能够确定内皮COUP-TFII与心肌COUP-TFII如何影响心脏发生，以及COUP-TFII如何调节心肌和内皮细胞之间的相互作用。我们提出的研究应该及时提供新的见解COUP-TFII如何影响心血管发育，并促进先天性心脏病的诊断和治疗。

DESCRIPTION (provided by applicant): COUP-TFII is an orphan nuclear receptor that belongs to the steroid receptor superfamily. Ablation of COUP-TFII in mice results in early embryonic lethality due to defects in angiogenesis and heart development. To further understand the biological functions of COUP-TFII in vascular and heart development, LacZ knock-in and floxed COUP-TFII mice were generated. X-Gal staining of the LacZ knock-in mice shows high COUP-TFII expression in the endothelium of the vein but not in the artery. Further, chimera analysis showed that COUP-TFII plays a cell autonomous function in the endothelial cells of the vein but not the artery. These studies show for the first time that COUP-TFII is an essential transcription factor for vein identify. The insertion of loxP site into the COUP-TFII locus reduced the expression of COUP-TFII, rendering the COUP-TFII flox/- mutants genetically hypomorphic. The hypomorphic mutants exhibit atrioventricular septal defects (AVSD) commonly observed in congenital heart disease patients. The atrium malformation displayed by the COUP-TFII null mutant coupled with AVSD elicited by the hypomorphic mutant together suggest that COUP-TFII plays a critical role in cardiogenesis. Whether the heart defects are intrinsic or secondary to the vascular defects is currently unknown. Proper heart development requires the coordinated interactions between the endocardium and myocardium. Whether the endothelial cells in the endocardium or the myocardial cells in the myocardium are the targets of COUP-TFII regulation is also unclear. To elucidate the role of COUP-TFII in the maintenance of vein identity and in heart development, two Specific Aims are proposed. In Aim 1, we will employ gain-of-function and loss-of-function of COUP-TFII in the endothelial cells to examine the role of COUP-TFII in the maintenance of arteriovenous identity. In addition, we will use DMA chip microarray analysis to identify novel downstream targets and signaling pathways that are regulated by COUP-TFII in the arteriovenous decision. In Aim 2, we will use the hypomorphic mutant and the endothelial and myocardial conditional COUP-TFII knockouts to investigate the role of COUP-TFII in heart development. This study will enable us to determine how endothelial COUP-TFII versus myocardial COUP-TFII affects cardiogenesis and how COUP-TFII modulates the interaction between the myocardium and endocardium. Our proposed studies should provide timely new insights into how COUP-TFII impacts cardiovascular development and facilitate the diagnosis and treatment of congenital heart disease.