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: 7983387
• 负责人: JOHN M SHANNON
• 金额: $ 48.41万
• 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/7983387
• 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; 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; Protein Family; 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）：肺中的气-液界面是一个高表面张力区域，如果未进行修改，会导致肺泡萎陷和呼吸衰竭。在正常条件下，由肺泡II型细胞合成和分泌的饱和磷脂组成的表面活性剂膜降低了这种高表面张力。肺表面活性物质还包含蛋白质家族SP-A、SP-B、SP-C和SP-D，其不同地有助于表面活性物质膜的形成、表面活性物质稳态和宿主防御。肺表面活性物质缺乏或改变与新生儿呼吸窘迫综合征（RDS）无争议相关，并有助于在成熟肺中观察到的急性呼吸窘迫综合征（ARDS）中的肺功能障碍。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，也可以通过涉及单饱和PC脱酰化然后再酰化的机制合成，通常用棕榈酸酯。对体外表面活性剂合成的研究表明，后一途径占II型细胞产生的DPPC的55- 75%。尽管30多年前在II型细胞中证明了用于再酰化的lysoPC酰基转移酶的活性，但迄今为止尚未鉴定出相应的基因。伴随本申请的数据表明，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（LPCAT 1）的小鼠cDNA。使用亚纯型转基因小鼠，我们还证明了LPCAT 1表达降低会降低发育中肺中的SatPC水平，并与存活率直接相关。我们将在三个具体目标中扩展这些研究。在第一个特定目标中，我们将完全克隆胎儿中的LPCAT 1基因，并确定这如何影响存活率，磷脂合成和肺中的整体基因表达。在特定目标2中，我们将产生LPCAT 1的条件性敲除，这将使我们能够定义成年动物中SatPC池大小和肺功能之间的关系。在具体目标3中，我们将利用LPCAT 1在SatPC合成中的作用，以确定其在启动SatPC转运至板层体中的作用。这些研究的完成将填补我们对表面活性物质磷脂合成的认识的重要空白，并可能显著影响RDS和其他因肺表面活性物质不足而导致的肺部疾病的治疗策略。 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，是出生时过渡到呼吸所必需的。肺表面活性物质缺乏与新生儿呼吸窘迫综合征（RDS）有关，也与成熟肺的急性呼吸窘迫综合征（ARDS）有关。LPCAT 1是一种对表面活性剂脂质的产生至关重要的酶。了解LPCAT 1在表面活性物质体内平衡中的功能将有助于开发治疗新生儿RDS和与肺表面活性物质不足相关的肺部疾病患者的新策略。