STRUCTURE AND FUNCTION OF SURFACTANT APOPROTEINS

功能性表面活性剂对于正常的呼吸来说是至关重要的。稀薄的血气屏障 包括肺泡表面活性物质的膜还必须保持无慢性炎症，这是面对每天暴露在数千升潜在污染空气中的挑战。表面活性蛋白最初以脂质结合和生物物理活性为基础，似乎有助于表面活性物质的动态平衡和肺稳定，以及多层肺泡免疫防御。我们的广泛目标是提供对表面活性蛋白如何执行这些双重作用以及它们的相对生理意义的更机械性的理解。我们的研究最终可能与与表面活性物质稳态异常直接相关的疾病相关，如急性呼吸窘迫综合征(太少)和肺泡蛋白沉积症(太多)，以及慢性炎症性疾病如BPD和COPD。我们建议检验一个普遍的假设，即通过表面活性蛋白A和D的离散序列和构象识别特定的配体在表面活性物质生理和宿主防御中介导双重的、有时是重叠的功能。我们的研究设计是基于结构产生功能这一老生常谈。我们将首先描述特定蛋白质-配体相互作用的结构基础，然后通过一系列功能实验来探索这些相互作用在肺泡生理学中的作用。我们将从定点蛋白突变和体外生化和细胞分析开始，并使用转基因小鼠模型进行体内研究。

A functional surfactant is critically required for normal respiration. The thin blood-gas barrier that includes the alveolar surfactant film must also be maintained free of chronic inflammation, a challenge in the face of daily exposure to thousands of liters of potentially contaminated air. The surfactant proteins, initially characterized on the basis of lipid-binding and biophysical activity, appear to contribute to both surfactant homeostasis and lung stability and a multilayered alveolar immune defense. Our broad objective is to provide a more mechanistic understanding of how the surfactant proteins perform these dual roles and their relative physiological significance. Our studies may ultimately be relevant to diseases directly linked to abnormal surfactant homeostasis such as acute respiratory distress syndromes (too little) and alveolar proteinosis (too much) as well as chronic inflammatory diseases such as BPD and COPD. We propose to test the general hypothesis that specific ligand recognition by discrete sequences and conformations of surfactant proteins A and D mediates dual and sometimes overlapping functions in surfactant physiology and host defense. Our study design is based on the truism that structure begets function. We will first characterize the structural basis of specific protein-ligand interactions and then explore the role of these interactions in alveolar physiology using a sequence of functional experiments. We will start with site-specific protein mutagenesis and in vitro biochemical and cellular assays and progress to studies in vivo using transgenic mouse models.