LPCAT1 is essential for perinatal lung function and survival

LPCAT1 对于围产期肺功能和生存至关重要

• 批准号: 8096793
• 负责人: JOHN M SHANNON
• 金额: $ 48.09万
• 依托单位: CINCINNATI CHILDRENS HOSP MED CTR
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8096793
• 关键词: Accounting; Acyltransferase; Adult; Adult Respiratory Distress Syndrome; Affect; Air; Alleles; Alveolar; Attention; Binding; Birth; Breathing; Breeding; Complementary DNA; Complex; Data; Distal; Enzymes; Epithelial Cells; Exons; Family; Fetus; Film; Functional disorder; Gases; Gene Expression; Genes; Histidine; Histopathology; Homeostasis; Host Defense; In Vitro; Inflammation; Knock-out; Knowledge; Lead; Lecithin; Link; Lipids; Liquid substance; Lung; Lung diseases; Mechanics; Mediating; Microarray Analysis; Molecular; Morphology; Mus; Newborn Infant; Palmitates; Pathway interactions; Patients; Perinatal; Phenotype; Phospholipid Transfer Proteins; Phospholipids; Production; Proteins; Pulmonary Surfactant-Associated Protein A; Pulmonary Surfactant-Associated Protein D; Pulmonary Surfactants; Respiratory Failure; Respiratory physiology; Role; Specificity; Structure; Surface; Surface Tension; Tertiary Protein Structure; Testing; Transgenes; Transgenic Mice; Type II Epithelial Receptor Cell; Virus; alveolar lamellar body; alveolar type II cell; deacylation; in vivo; lipid transfer protein; mRNA Expression; mature animal; member; mortality; neonatal death; neonate; postnatal; public health relevance; pulmonary function; research study; respiratory distress syndrome; steroidogenic acute regulatory protein; surfactant; surfactant deficiency; trafficking; treatment strategy

DESCRIPTION (provided by applicant): The air-liquid interface in the lung is a region of high surface tension that, if unmodified, causes alveolar collapse and respiratory failure. Under normal conditions, a surfactant film consisting of saturated phospholipids that is synthesized and secreted by alveolar type II cells reduces this high surface tension. Pulmonary surfactant also contains a family of proteins, SP-A, SP-B, SP-C, and SP-D, which variously contribute to formation of the surfactant film, surfactant homeostasis, and host defense. Pulmonary surfactant deficiency or alteration has been incontrovertibly linked to respiratory distress syndrome (RDS) in neonates and contributes to the lung dysfunction seen in acute respiratory distress syndrome (ARDS) in the mature lung. Phospholipids constitute approximately 85% of the mass of pulmonary surfactant. The single most abundant phospholipid, is saturated phosphatidylcholine (SatPC), particularly dipalmitoylphosphatidylcholine (DPPC). SatPC can be synthesized either de novo or by a mechanism involving the deacylation of monosaturated PC followed by reacylation, usually with palmitate. Studies on surfactant synthesis in vitro have shown that the latter pathway accounts for 55- 75% of the DPPC made by type II cells. Although activity of a lysoPC acyltransferase utilized in reacylation was demonstrated in type II cells over 30 years ago, the corresponding gene has not been heretofore identified. Data accompanying this application demonstrate that we have identified and isolated the mouse cDNA for a lysoPC acyltransferase (LPCAT1) that is highly enriched in type II cells. Using a hypomorphic transgenic mouse, we also demonstrated that decreased LPCAT1 expression reduces SatPC levels in the developing lung and directly correlates with survival. We will extend these studies in three Specific Aims. In the first Specific Aim we will completely inactivate the LPCAT1 gene in the fetus and determine how this affects survival, phospholipid synthesis, and overall gene expression in the lung. In Specific Aim 2 we will generate a conditional knockout of LPCAT1 that will allow us to define the relationship between SatPC pool size and lung function in the adult animal. In Specific Aim 3 we will exploit the role of LPCAT1 in SatPC synthesis to determine its role in the initiation of SatPC transport to lamellar bodies. The completion of these studies will fill important gaps in our knowledge regarding surfactant phospholipid synthesis, and may significantly impact strategies for the treatment of RDS and other lung diseases resulting from an insufficiency in pulmonary surfactant. PUBLIC HEALTH RELEVANCE: Pulmonary surfactant, a complex of lipids and proteins, is absolutely required for making the transition to breathing at birth. A deficit in surfactant is incontrovertibly linked to respiratory distress syndrome (RDS) in newborn infants, and is also associated with acute respiratory distress syndrome (ARDS) in the mature lung. LPCAT1 is an enzyme critical for the production of surfactant lipids. Understanding how LPCAT1 functions in surfactant homeostasis will help develop new strategies for treating RDS in newborns and in patients with lung disease related to inadequate pulmonary surfactant.

描述（由申请人提供）：肺部的气液界面是一个具有高表面张力的区域，如果不加以改变，会导致肺泡塌陷和呼吸衰竭。在正常情况下，由 II 型肺泡细胞合成和分泌的饱和磷脂组成的表面活性剂膜会降低这种高表面张力。肺表面活性剂还含有一系列蛋白质，SP-A、SP-B、SP-C 和 SP-D，它们对表面活性剂膜的形成、表面活性剂稳态和宿主防御有不同的贡献。肺表面活性物质缺乏或改变无疑与新生儿呼吸窘迫综合征（RDS）有关，并导致成熟肺中急性呼吸窘迫综合征（ARDS）中出现的肺功能障碍。磷脂约占肺表面活性物质质量的85%。最丰富的单一磷脂是饱和磷脂酰胆碱（SatPC），特别是二棕榈酰磷脂酰胆碱（DPPC）。 SatPC 可以从头合成，也可以通过单饱和 PC 脱酰基化，然后再酰化（通常使用棕榈酸酯）的机制来合成。体外表面活性剂合成研究表明，II 型细胞产生的 DPPC 中，后一种途径占 55-75%。尽管用于再酰化的lysoPC酰基转移酶的活性已在30多年前在II型细胞中得到证实，但迄今为止尚未鉴定出相应的基因。本申请附带的数据表明，我们已经鉴定并分离了在 II 型细胞中高度富集的 lysoPC 酰基转移酶 (LPCAT1) 的小鼠 cDNA。使用低等态转基因小鼠，我们还证明，LPCAT1 表达减少会降低发育中肺部的 SatPC 水平，并与生存直接相关。我们将在三个具体目标中扩展这些研究。在第一个具体目标中，我们将完全灭活胎儿中的 LPCAT1 基因，并确定这如何影响肺部的存活、磷脂合成和整体基因表达。在特定目标 2 中，我们将产生 LPCAT1 的条件敲除，这将使我们能够定义 SatPC 池大小与成年动物肺功能之间的关系。在具体目标 3 中，我们将利用 LPCAT1 在 SatPC 合成中的作用来确定其在 SatPC 向层状体运输的起始过程中的作用。这些研究的完成将填补我们在表面活性剂磷脂合成方面的知识空白，并可能显着影响治疗 RDS 和因肺表面活性剂不足引起的其他肺部疾病的策略。 公共卫生相关性：肺表面活性物质是一种脂质和蛋白质的复合物，对于出生时过渡到呼吸绝对是必需的。毫无疑问，表面活性剂的缺乏与新生儿的呼吸窘迫综合征（RDS）有关，也与成熟肺部的急性呼吸窘迫综合征（ARDS）有关。 LPCAT1 是一种对于表面活性剂脂质的生产至关重要的酶。了解 LPCAT1 如何在表面活性剂稳态中发挥作用将有助于制定治疗新生儿 RDS 以及因肺表面活性剂不足相关的肺部疾病患者的新策略。