Urokinase-type plasminogen activator (uPA) stimulates triglyceride synthesis in Huh7 hepatoma cells via p38-dependent upregulation of DGAT2
| Autor: | Raymond Coleman, Bianca Fuhrman, Aviva Gamliel-Lazarovich, Nicole Paland |
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| Rok vydání: | 2014 |
| Předmět: |
Male
medicine.medical_specialty Carcinoma Hepatocellular Biology p38 Mitogen-Activated Protein Kinases chemistry.chemical_compound Mice Internal medicine Lipid droplet Cell Line Tumor medicine Animals Humans Diacylglycerol O-Acyltransferase Diglyceride acyltransferase Triglycerides chemistry.chemical_classification Triglyceride Dose-Response Relationship Drug Activator (genetics) Gene Expression Profiling Fatty liver Fatty Acids Liver Neoplasms Fatty acid medicine.disease Lipids Urokinase-Type Plasminogen Activator Up-Regulation Urokinase receptor Gene Expression Regulation Neoplastic Mice Inbred C57BL Endocrinology chemistry Liver Cardiology and Cardiovascular Medicine Sterol Regulatory Element Binding Protein 1 Plasminogen activator |
| Zdroj: | Atherosclerosis. 237(1) |
| ISSN: | 1879-1484 |
| Popis: | Objective: The liver is the central organ of fatty acid and triglyceride metabolism. Oxidation and synthesis of fatty acids and triglycerides is under the control of peroxisome-proliferator-activated receptors (PPAR) a. Impairment of these receptors' function contributes to the accumulation of triglycerides in the liver resulting in non-alcoholic fatty liver disease. Urokinase-type plasminogen activator (uPA) was shown to regulate gene expression in the liver involving PPARg transcriptional activity. In this study we questioned whether uPA modulates triglyceride metabolism in the liver, and investigated the mechanisms involved in the observed processes. Methods and results: Huh7 hepatoma cells were incubated with increasing concentrations of uPA for 24 h uPA dose-dependently increased the cellular triglyceride mass, and this effect resulted from increased de novo triglyceride synthesis mediated by the enzyme diglyceride acyltransferase 2 (DGAT2). Also, the amount of free fatty acids was highly up regulated by uPA through activation of the transcription factor SREBP-1. Chemical activation of PPAR a further increased uPA-stimulated triglyceride synthesis, whereas inhibition of p38, an upstream activator of PPARa, completely abolished the stimulatory effect of uPA on both triglyceride synthesis and DGAT2 upregulation. The effect of uPA on triglyceride synthesis in Huh7 cells was mediated via binding to its receptor, the uPAR. In vivo studies in uPAR � /� mice demonstrated that no lipid droplets were observed in their livers compared to C57BL/6 mice and the triglyceride levels were significantly lower. Conclusion: This study presents a new biological function of the uPA/uPAR system in the metabolism of triglycerides and might present a new target for an early therapeutic intervention for NAFLD. |
| Databáze: | OpenAIRE |
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