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）：肺中的空气界面是高表面张力的区域，如果未修饰，会导致肺泡塌陷和呼吸衰竭。在正常条件下，由饱和磷脂组成的表面活性剂膜由肺泡II型细胞合成和分泌，可降低这种高表面张力。肺表面活性剂还包含一个蛋白质，SP-A，SP-B，SP-C和SP-D，它们有助于形成表面活性剂膜，表面活性剂稳态和宿主防御。肺表面活性剂缺乏或改变与新生儿中的呼吸窘迫综合征（RDS）无关，并导致成熟肺中急性呼吸道遇险综合征（ARDS）中发现的肺部功能障碍。磷脂约占肺表面活性剂质量的85％。单个最丰富的磷脂是饱和的磷脂酰胆碱（SATPC），尤其是二甲米酰磷脂酰胆碱（DPPC）。可以从头开始合成SATPC，也可以通过涉及单饱和PC的脱酰化的机制进行合成，然后再重新化，通常与棕榈酸盐。关于体外表面活性剂合成的研究表明，后一种途径占II型细胞制造的DPPC的55-75％。尽管在30年前的II型细胞中证明了在重新酰化中使用的lysoPC酰基转移酶的活性，但尚未确定相应的基因。伴随该应用的数据表明，我们已经确定并分离了高度富集在II型细胞中的Lysopc酰基转移酶（LPCAT1）的小鼠cDNA。使用型型转基因小鼠，我们还证明了LPCAT1表达降低会降低发育中的肺中的SATPC水平，并与生存直接相关。我们将以三个具体的目标扩展这些研究。在第一个特定目的中，我们将完全使胎儿中的LPCAT1基因失活，并确定这如何影响肺中的生存，磷脂合成和总体基因表达。在特定目标2中，我们将产生一个有条件的LPCAT1敲除，这将使我们能够定义成年动物中SATPC池大小与肺功能之间的关系。在特定目标3中，我们将利用LPCAT1在SATPC合成中的作用，以确定其在SATPC运输到层状体中的作用。这些研究的完成将填补我们关于表面活性剂磷脂合成的重要空白，并可能会对治疗RDS和其他肺部疾病的治疗策略产生重大影响，这是由于肺部表面活性剂不足而导致的。 公共卫生相关性：肺表面活性剂是一种脂质和蛋白质的复合物，绝对需要在出生时过渡到呼吸。表面活性剂的赤字与新生婴儿的呼吸窘迫综合征（RDS）无关，并且也与成熟肺中的急性呼吸遇险综合征（ARDS）有关。 LPCAT1是一种对表面活性剂脂质产生至关重要的酶。了解LPCAT1在表面活性剂稳态中的功能如何有助于制定新生儿和与肺部表面活性剂不足的肺部疾病患者治疗RDS的新策略。