Chondroitin Sulfate Proteoglycans in Lung Development

描述(申请人提供)：正常的肺发育需要许多生物活性分子在时间和空间上的正确表达。其中许多分子是可溶的，包括激素、生长因子、生物活性多肽和细胞因子。不溶性细胞外基质(ECM)的成分，包括蛋白多糖(PGs)，也被证明在正常的肺生长和分化中发挥重要作用。PGS是一类不同的分子，作为组织发育的结构底物，充当特定生长因子的结合库，并介导细胞-ECM、细胞-细胞和配体-受体相互作用等过程。我们的初步实验表明，硫酸前列腺素是肺形态发生和上皮分化所必需的。进一步的实验表明，破坏PGs的一个亚类，硫酸软骨素蛋白多糖(CSPGs)，在体外对肺生长和分支有显著的抑制作用。根据这些数据，我们假设CSPG在正常的肺发育中起着重要作用(S)。在这项提议中，我们将分两个阶段检验这一假设。在第一阶段(特异性目标1和2)，我们将使用体外模型来证实和扩展我们的初步观察，即抑制PGs抑制肺生长、形态发生和上皮分化，并确定哪些作用是由于CSPGs的破坏所致。在第二阶段(具体目标3)，我们将确定我们的体外观察如何转化为体内的肺发育。针对转基因小鼠肺的嵌合细菌软骨素酶(S)的条件表达将使我们能够评估CSPGs在体内肺发育的三个不同阶段中的重要性：分支形态发生、肺表面活性物质系统成熟和出生后肺泡化。该项目的完成将填补我们对CSPGs在肺形态发生和分化中的作用的认识上的一个重大空白，并将确定CSPGs的中断是否会导致类似于新生儿临床疾病的肺部病理。这一知识将为预防和治疗由肺发育不全和不成熟引起的肺部疾病制定新的战略。

DESCRIPTION (provided by applicant): Normal lung development requires the temporally and spatially correct expression of numerous biologically-active molecules. Many of these molecules are soluble and include hormones, growth factors, bioactive peptides, and cytokines. Components of the insoluble extracellular matrix (ECM), including proteoglycans (PGs), have also been shown to play important roles in normal lung growth and differentiation. PGs are a diverse class of molecules that serve as structural substrata in which tissues develop, act as binding reservoirs for specific growth factors, and mediate such processes as cell-ECM, cell-cell, and ligand-receptor interactions. Our preliminary experiments have shown that sulfated PGs are required for lung morphogenesis and epithelial differentiation. Further experiments demonstrated that disrupting one subclass of PGs, chondroitin sulfate proteoglycans (CSPGs), had marked inhibitory effects on lung growth and branching in vitro. From these data we have hypothesized that CSPGs play an essential role(s) in normal lung development. In this proposal, we will test this hypothesis in two phases. In the first phase (Specific Aims 1 and 2), we will use in vitro models to confirm and extend our preliminary observations that inhibition of PGs suppresses lung growth, morphogenesis, and epithelial differentiation, and to define which effects are due to the disruption of CSPGs. In the second phase (Specific Aim 3), we will determine how our in vitro observations translate to lung development in vivo. Conditional expression of chimeric bacterial chondroitinase(s) targeted to the lungs of transgenic mice will allow us to assess the importance of CSPGs in three distinct phases of lung development in vivo: branching morphogenesis, maturation of the pulmonary surfactant system, and postnatal alveolization. Completion of this project will fill a significant gap in our understanding of the role of CSPGs in lung morphogenesis and differentiation, and will determine whether disruption of CSPGs causes lung pathologies similar to clinical disease in neonates. This knowledge will allow the development of new strategies for the prevention and treatment of lung diseases resulting from lung hypoplasia and immaturity.