ABCA3 and the Response to Lung Injury

描述(申请人提供)：ATP结合盒转运体ABCA3的突变与新生儿致命的表面活性物质缺乏和呼吸窘迫综合征(RDS)以及年龄较大的儿童和成人的间质性肺部疾病有关。ABCA3位于板层小体的界膜上，对板层小体的发生和肺泡2型上皮细胞中磷脂的运输起着至关重要的作用。ABCA3突变是一种称为“构象障碍”的疾病的一部分，在这些疾病中，突变的蛋白质被错误折叠，保留在内质网(ER)中，并被泛素蛋白酶体降解。当这个质量控制系统不堪重负时，突变蛋白在内质网中积累，并触发应激和其他蛋白质的激活/表达(内质网应激)。某些ABCA3转运突变体可以通过促进适当折叠和改善转运的蛋白质伴侣在体外被拯救。我们最近证明，尽管ABCA3小鼠磷脂合成减少，但它们可以存活到成年，ABCA3-/-小鼠无法形成板层小体，成熟SP-B的表达受到干扰，它们的肺无法膨胀，出生后不久就会死亡。利用野生型纯合子空白小鼠或与人类疾病相关的突变的ABCA3纯合子小鼠的转基因重建，我们打算建立人类疾病的小鼠模型，确定它们对肺损伤的反应，并测试限制不良反应的潜在治疗方法。我们假设，人类ABCA3突变在小鼠体内的表达将提供一个人类疾病的模型，杂合子和突变的ABCA3小鼠将更容易受到博莱霉素和高氧诱导的肺损伤。此外，我们假设ABCA3突变与透明质酸(HA)及其受体的增加有关，透明质酸(HA)及其受体促进巨噬细胞聚集，使用抗HA或受体策略可以改善这种情况。具体目标1将确定野生型和ABCA3，以及野生型或ABCA3突变条件表达的小鼠对博莱霉素和高氧诱导的肺损伤的反应。特殊目标2将检测从经WT或ABCA3突变重组的ABCA3-/-小鼠中分离的肺泡II型细胞，以确定板层小体形态、ER应激反应的存在，并将测试化学伴侣和抗HA/受体方法对ER应激反应的影响。具体目标3将确定伴侣和抗HA/受体方法对WT或ABCA3突变重组小鼠对博莱霉素或高氧诱导的肺损伤的反应的影响。与公共卫生相关：ABCA3转运蛋白基因的突变会导致多种肺部疾病，这些疾病要么会导致新生儿立即死亡，要么会导致儿童和成年后的慢性肺部疾病。我们想要建立人类该基因突变的小鼠模型，以研究它们对肺损伤的易感性，疾病的机制，并测试潜在的治疗方法。由于它们与肺损伤后的炎症有关，我们也有兴趣研究细胞外基质分子透明质酸(HA)及其受体在与ABCA3突变相关的疾病过程中的作用。我们相信，这些研究的数据将对遗传性肺部疾病的发病机制产生影响，并为潜在治疗方法的开发提供重要信息。此外，这些研究的发现将与其他严重的肺部疾病(例如囊性纤维化)和肝脏(例如阿尔法-1-抗胰蛋白酶缺乏症)相关，这些疾病具有类似的发病机制。

DESCRIPTION (provided by applicant): Mutations in the ATP-binding cassette transporter ABCA3 are associated with fatal surfactant deficiency and Respiratory Distress Syndrome (RDS) in neonates, and interstitial lung disease in older children and adults. Located in the limiting membrane of lamellar bodies, ABCA3 is critical for lamellar body genesis and the transport of phospholipid in alveolar type 2 epithelial cells. ABCA3 mutations form part of a growing number of diseases termed "conformational disorders" in which the mutant protein is misfolded, retained in the endoplasmic reticulum (ER) and degraded by ubiquitinproteosome degradation. When this quality control system is overwhelmed, mutant protein accumulates in the ER and triggers the activation/expression of stress and other proteins (ER Stress). Certain ABCA3 trafficking mutants can be rescued in vitro by protein chaperones that promote appropriate folding and improved trafficking. We have recently demonstrated that although ABCA3 mice have decreased phospholipid synthesis, they survive to adulthood, and ABCA3-/- mice fail to form lamellar bodies, the expression of mature SP-B is disrupted, their lungs fail to inflate and they die soon after birth. Using transgenic reconstitution of homozygous null mice with wild type or ABCA3 with mutations associated with human disease, we intend to develop mouse models of the human disease, determine their response to lung injury and test potential therapeutics for limiting adverse effects. We hypothesize that expression of human mutations of ABCA3 in mice will provide a model of human disease, and that heterozygous and mutant ABCA3 mice will be more susceptible to bleomycin- and hyperoxia-induced lung injury. Further, we hypothesize that ABCA3 mutations are associated with increases in hyaluronan (HA) and its receptors that promote macrophage accumulation, and which can be ameliorated using anti-HA or -receptor strategies. Specific Aim 1 will determine the response of wild type and ABCA3, as well as mice with conditional expression of wild type or ABCA3 mutations, to bleomycin- and hyperoxia-induced lung injury. Specific Aim 2 will examine alveolar type II cells isolated from ABCA3-/- mice reconstituted with WT or ABCA3 mutations to determine lamellar body morphology, the presence of ER stress response, and will test chemical chaperones and anti-HA/receptor approaches for their effects on the ER stress response. Specific Aim 3 will determine the effects of chaperones and anti-HA/receptor approaches on the response to bleomycin- or hyperoxia-induced lung injury in mice reconstituted with WT or ABCA3 mutations. PUBLIC HEALTH RELEVANCE: Mutations in the gene for the ABCA3 transporter cause a variety of lung diseases that result in either death in the immediate newborn period or chronic lung disease in children and into adulthood. We want to develop mouse models of the human mutations in this gene so as to study their susceptibility to lung injury, the mechanisms of disease, and to test potential therapies. Since they have been implicated in inflammation after lung injury, we are also interested in studying the role of the extracellular matrix molecule hyaluronan (HA) and its receptors in the disease processes associated with ABCA3 mutations. We believe that the data from these studies will have implications for the pathogenesis of genetic lung diseases as well as provide vital information in the development of potential therapies. Further, the findings emanating from these studies will be relevant to other severe conditions of the lung (e.g. cystic fibrosis) and liver (e.g. alpha-1-antitrypsin deficiency) that have similar mechanisms of disease.