Coordination of pulmonary vascular development by Prx1

描述（由申请人提供）：同源盒基因编码控制组织模式和形态发生的转录因子，但它们在肺血管发育中的作用尚不清楚。我们的初步研究表明，配对的同源盒基因Prxl通过促进内皮细胞（EC）分化和血管网络形成的能力，是肺血管化所必需的。本提案的具体目的如下：(1)确定Prxl如何在肺血管发生过程中驱动EC分化：将使用Tie-GFP转基因小鼠定位在肺发育过程中表达Prxl的EC，并使用染色质免疫沉淀法确定Prxl在肺EC分化中的直接靶点。利用Prxl缺失小鼠和肺EC分化组织培养模型，评价Prxl及其靶点的有效性和功能；(2)为了确定prxl依赖的细胞外基质蛋白tenascin- C （TN-C）诱导如何促进肺血管网络的形成：将使用胎儿肺外植体、酵母2-杂交试验和组织重组进行敲除研究，以了解TN-C如何促进prxl依赖的网络形成；(3)阐明局灶黏附激酶（FAK）在血管网络形成过程中如何控制Prxl：腺病毒抑制FAK活性，解剖Prxl基因启动子，将有助于理解FAK如何控制Prxl转录和肺血管形态发生。

DESCRIPTION (provided by applicant): Homeobox genes encode transcription factors that control tissue patterning and morphogenesis, yet their role in pulmonary vascular development remains obscure. Our preliminary studies indicate that the paired related homeobox gene, Prxl, is required for lung vascularization via its ability to promote both endothelial cell (EC) differentiation and vascular network formation. The Specific Aims of this proposal are as follows: (1) To define how Prxl drives EC differentiation during lung vasculogenesis: Tie-GFP transgenic mice will be used to locate Prxl-expressing ECs throughout lung development, and chromatin immunoprecipitation assays will be used to identify direct targets for Prxl in differentiating lung ECs. The validity and functions of Prxl and its targets will be evaluated using Prxl-null mice and tissue culture models of pulmonary EC differentiation; (2) To determine how Prxl-dependent induction of the extracellular matrix protein tenascin- C (TN-C) promotes lung vascular network formation: Knockout studies using fetal lung explants, yeast 2- hybrid assays and tissue recombinations will be used to understand how TN-C promotes Prxl-dependent network formation; (3) To delineate how focal adhesion kinase (FAK) controls Prxl during vascular network formation: Adenoviral-based inhibition of FAK activity, and dissection of the Prxl gene promoter will be used to comprehend how FAK controls Prxl transcription and vascular morphogenesis in the lung. Overall, this proposal will result in a detailed understanding of the role of Prxl throughout fetal lung vascularization. This study should provide new concepts in lung vascular biology, and will hopefully result in novel diagnostic tools and therapies for the treatment of newborn and adult diseases in which the pulmonary vasculature is compromised, eg. bronchopulmonary dysplasia and pulmonary hypertension.