THE INTEGRATED ROLES OF IPLA2G IN OBESITY, INFLAMMATION AND HEPATIC DYSFUNCTION

IPLA2G 在肥胖、炎症和肝功能障碍中的综合作用

• 批准号: 9325506
• 负责人: RICHARD W GROSS
• 金额: $ 34.31万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-25 至 2019-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9325506
• 关键词: Ablation; Active Sites; Adipocytes; Affect; Animals; Attenuated; Bioenergetics; Biological Assay; Calcium; Cause of Death; Communication; Consumption; Coupling; Development; Diabetes Mellitus; Diagnostic; Diglycerides; Eicosanoids; Energy Metabolism; Enzymes; Euglycemic Clamping; Exhibits; Fatty Liver; Fatty acid glycerol esters; Functional disorder; Generations; Genetic; Genetic Models; Goals; Hepatic; Hepatocyte; High Fat Diet; IRS1 gene; Industrialization; Inflammation; Inflammatory; Insulin Resistance; Knock-out; Knockout Mice; Lead; Lipids; Liver; Liver diseases; LoxP-flanked allele; Mass Spectrum Analysis; Mediating; Mediator of activation protein; Metabolic; Metabolism; Mitochondria; Molecular; Monoglycerides; Morbidity - disease rate; Mus; Muscle Cells; Muscle Fibers; Obesity; Obesity associated disease; Organ; Organelles; Pathologic; Pathology; Patients; Pharmacological Treatment; Pharmacology; Phenotype; Phospholipase; Phosphorylation; Physiological; Process; Production; Protein Isoforms; Reagent; Research; Resistance; Respiration; Role; Signal Transduction; Skeletal Muscle; Societies; System; Technology; Tissues; Transgenic Organisms; Triglycerides; Validation; body system; cell type; experimental study; feeding; glucose tolerance; glucose uptake; glycogenolysis; hepatic gluconeogenesis; improved; in vivo; insight; insulin sensitivity; insulin signaling; interdisciplinary approach; lipid mediator; lipid metabolism; liver inflammation; loss of function; metabolomics; mitochondrial dysfunction; mitochondrial metabolism; mortality; novel; novel strategies; obesity treatment; peroxisome; public health relevance; screening; skeletal muscle metabolism; spatiotemporal; synergism; transacylation

DESCRIPTION (provided by applicant): The major causes of mortality and morbidity in industrialized societies result from the multiple downstream sequelae of high fat diet-induced obesity (HFDIO). Previously, we demonstrated the importance of calciumindependent phospholipase A2γ(iPLA2γ) as a central enzymic mediator integrating cellular signaling and organismal bioenergetics through the generation and characterization of a global iPLA2γ KO mouse. Remarkably, the iPLA2γ knockout mouse was completely resistant to HFDIO and the development of insulin resistance. However, due to the multiple organ systems affected in the whole animal iPLA2γ knockout, the mechanistic roles of iPLA2γ in each tissue contributing to the complete resistance of this mouse to HFDIO are unknown. The overarching goal of the proposed research is the mechanistic determination of the tissue- and organelle-specific roles of iPLA2γ in promoting inflammation, maladaptive cellular signaling and dysfunctional bioenergetics that result in insulin resistance and the pathologic end-organ sequelae of HFDIO. Accordingly, we generated mice containing a floxed construct of the iPLA2γ active site which has been crossed with tissue specific Cre mice resulting in the generation of hepatocyte-specific and skeletal muscle myocyte-specific iPLA2γ knockout mice. The proposed research will synergistically use these enabling genetic models in conjunction with the integrated lipidomics and metabolomics platforms we developed to identify the mechanisms through which iPLA2γ participates in the development of obesity, inflammation, and insulin resistance during HFDIO. The first specific aim will identify the roles of hepatocyte-specific iPLA2γ in mediating alterations in the generation of lipid 2nd messengers, lipid metabolism, hepatosteatosis and bioenergetics during HFDIO unencumbered by the effects of iPLA2γ loss of function in other cell types that are present in the germline knockout. In Specific Aim 2, we will examine the effects of skeletal muscle myocyte-specific ablation of iPLA2γ on skeletal muscle metabolism, insulin resistance and mitochondrial dysfunction that are present during high fat feeding in WT mice, but are rescued in the germline knockout mouse. Finally, in Specific Aim 3, we will determine the interactive mechanistic roles of the organelle-specific isoforms of iPLA2γ through the transgenic reintroduction of either the mitochondrial-specific or peroxisomal-specific isoforms of iPLA2γ into the hepatocyte-specific iPLA2γ knockout mouse. Moreover, the mechanisms through which lipid 2nd messengers generated by iPLA2γ in hepatocytes, skeletal muscle myocytes and adipocytes mediate inter-organ communication between these metabolically interwoven tissues will be identified through synergistic highly penetrating technologies we have developed/refined. Through this multidisciplinary approach employing novel genetic reagents, high mass accuracy mass spectrometry technologies and integrated chemophysiologic approaches, novel pharmacologic targets to attenuate the sequelae of HFDIO can be identified.

描述（由申请人提供）：工业化社会中死亡和发病的主要原因是高脂肪饮食引起的肥胖（HFDIO）的多种下游后遗症造成的。此前，我们通过全局 iPLA2γ KO 小鼠的生成和表征，证明了钙非依赖性磷脂酶 A2γ（iPLA2γ）作为整合细胞信号传导和生物体生物能学的中心酶介质的重要性。值得注意的是，iPLA2γ 敲除小鼠对 HFDIO 和胰岛素抵抗的发展完全具有抵抗力。然而，由于整个动物 iPLA2γ 敲除影响了多个器官系统，因此 iPLA2γ 在每个组织中对小鼠对 HFDIO 完全抵抗的机制作用尚不清楚。该研究的总体目标是从机制上确定 iPLA2γ 在促进炎症、适应不良的细胞信号传导和功能失调的生物能学方面的组织和细胞器特异性作用，从而导致胰岛素抵抗和 HFDIO 的病理性终末器官后遗症。因此，我们生成了含有 iPLA2γ 活性位点 floxed 构建体的小鼠，该小鼠已与组织特异性 Cre 小鼠杂交，从而产生了肝细胞特异性和骨骼肌肌细胞特异性 iPLA2γ 敲除小鼠。拟议的研究将协同使用这些使能遗传模型与我们开发的集成脂质组学和代谢组学平台相结合，以确定 iPLA2γ 参与 HFDIO 期间肥胖、炎症和胰岛素抵抗发展的机制。第一个具体目标是确定肝细胞特异性 iPLA2γ 在介导 HFDIO 期间脂质第二信使生成、脂质代谢、肝脂肪变性和生物能学变化中的作用，而不受生殖系敲除中存在的其他细胞类型中 iPLA2γ 功能丧失的影响。在具体目标 2 中，我们将研究骨骼肌肌细胞特异性消除 iPLA2γ 对骨骼肌代谢、胰岛素抵抗和线粒体功能障碍的影响，这些功能在 WT 小鼠高脂肪喂养期间存在，但在种系基因敲除小鼠中得到恢复。最后，在具体目标 3 中，我们将通过将线粒体特异性或过氧化物酶体特异性 iPLA2γ 亚型转基因重新引入肝细胞特异性 iPLA2γ 敲除小鼠中，确定 iPLA2γ 细胞器特异性亚型的相互作用机制作用。此外，通过我们开发/完善的协同高度渗透技术，将确定肝细胞、骨骼肌肌细胞和脂肪细胞中 iPLA2γ 产生的脂质第二信使介导这些代谢交织组织之间器官间通讯的机制。通过这种采用新型遗传试剂、高精度质谱技术和综合化学生理学方法的多学科方法，可以确定减轻 HFDIO 后遗症的新药理学靶点。