Hyaluronan in Lung Vascular Development

描述（由申请人提供）： 肺发育涉及模式形成基因、转录因子、激素和生长因子以及协调肺分支形态发生和交换的细胞外基质的复杂遗传等级。 本研究的重点是促血管生成因子和抗血管生成因子、糖胺聚糖透明质酸（透明质酸，HA）及其受体CD 44和RHAMM在胚胎血管和出生后肺泡发育中的作用。 初步数据表明：（1）。外源性bFGF、VEGF和低分子量HA可促进肺芽外植体血管化。HA、CD 44和RHAMM调节内皮细胞功能和血管生成，3）。出生后缺氧降低内皮细胞含量并抑制与增加的TGF β相关的肺泡形成，和4）。在缺氧时用抗TGF β抗体治疗或在不能激活TGF β的CD 44和β 6整联蛋白亚基缺失小鼠中恢复正常肺泡形成。 使用这些模型，我们将测试的假设，即亲和抗血管生成生长因子的信号，由透明质酸及其受体直接调节肺血管和出生后肺泡的发展。 目的1：研究HA及其受体在野生型小鼠以及CD 44和RHAMM基因敲除小鼠中的发育和出生后表达与肺血管发育和肺泡形成的关系。 目的2：探讨生长因子和透明质酸对肺血管化的调控作用，并利用胚胎肺芽组织、外源性VEGF、bFGF、透明质酸寡糖和多种干扰透明质酸受体功能的阻断剂，研究透明质酸及其受体在肺血管化中的作用。 目的3将使用TGF β的阻断抗体和不能激活TGF β的基因敲除小鼠来检查TGF β、HA及其受体在缺氧、地塞米松和/或维甲酸的情况下在出生后肺泡发育中的作用。 由于CD 44和RHAMM是普遍表达的，目的4将确定细胞特异性敲除CD 44和RHAMM对胚胎肺血管化和肺泡发育的影响。 在拟议的研究中，将使用MRI成像、计算机生成的3-D重建和组织学形态测量来定义肺结构。 将使用无创体积描记法和运动试验确定肺功能。 本提案中描述的实验将确定生长因子、HA及其受体对肺血管发育以及最终对肺泡形成和肺功能的贡献。 了解肺血管化的调控机制将为增强肺血管化和肺泡化提供新的见解，并可能导致新的方法。

DESCRIPTION (provided by applicant): Lung development involves an intricate genetic hierarchy of pattern formation genes, transcription factors, hormones and growth factors, and the extracellular matrix that co-ordinate lung branching morphogenesis and exchange. This proposal focuses on the role of pro- and anti-angiogenic growth factors, the glycosaminoglycan hyaluronan (hyaluronic acid, HA) and it s receptors CD44 and RHAMM, in both embryonic vascular and postnatal alveolar development. Preliminary data demonstrate that 1). Vascularization of lung bud explants can be stimulated by exogenous bFGF, VEGF and low molecular weight HA, 2). HA, CD44 and RHAMM regulate endothelial cell functions and angiogenesis, 3). Postnatal hypoxia decreases endothelial cell content and inhibits alveolization in association with increased TGFbeta, and 4). Normal alveolizaton is restored in the face of hypoxia with anti- TGFbeta antibody treatment or in CD44 and beta6 integrin subunit null mice that fail to activate TGFbeta. Using these models, we will test the hypothesis that pro- and anti-angiogenic growth factor signals that are regulated by hyaluronan and its receptors direct lung vascular and postnatal alveolar development. Aim 1 will characterize the developmental and postnatal expression of HA and its receptors in relation lung vascular development and alveolization in wild type, as well as CD44 and RHAMM null mice. Aim 2 will focus on growth factor and HA regulation of lung Vascularization and examine the contribution of HA and its receptors using embryonic lung bud explants, exogenous VEGF, bFGF, HA oligosaccharides and a variety of blocking agents that interfere with HA receptor function. Aim 3 will examine the role of TGFbeta, HA and its receptors in postnatal alveolar development in the face of hypoxia, dexamethasone and/or retinoic acid using blocking antibody to TGFbeta and knockout mice that fail to activate TGFbeta. Since CD44 and RHAMM are ubiquitously expressed, Aim 4 will determine the effects of cell-specific knockouts of CD44 and RHAMM on both embryonic lung Vascularization and alveolar development. In the proposed studies, lung structure will be defined using MRI imaging, computer-generated 3-D reconstructions, and histologic morphometry. Lung function will be determined using non-invasive plethysmography and exercise testing. The experiments described in this proposal will define the contribution of growth factors, HA and its receptors to pulmonary vascular development and ultimately to alveolar formation and pulmonary function. Understanding of the regulation of lung Vascularization will provide new insights into and may lead to novel approaches for augmenting lung Vascularization and alveolization.