title: Disruption of Lipid Raft Function Increases Expression and Secretion of Monocyte Chemoattractant Protein-1 in 3T3-L1 Adipocytes.
abstract: The adipocyte is unique in its capacity to store lipids. In addition to triglycerides, the adipocyte stores a significant amount of cholesterol. Moreover, obese adipocytes are characterized by a redistribution of cholesterol with depleted cholesterol in the plasma membrane, suggesting that cholesterol perturbation may play a role in adipocyte dysfunction. We used methyl-β-cyclodextrin (MβCD), a molecule with high affinity for cholesterol, to rapidly deplete cholesterol level in differentiated 3T3-L1 adipocytes. We tested whether this perturbation altered adipocyte secretion of monocyte chemoattractant protein-1 (MCP-1), a chemokine that is elevated in obesity and is linked to obesity-associated chronic diseases. Depletion of cholesterol by MβCD increased MCP-1 secretion as well as the mRNA and protein levels, suggesting perturbation at biosynthesis and secretion. Pharmacological inhibition revealed that NF-κB, but not MEK, p38 and JNK, was involved in MβCD-stimulated MCP-1 biosynthesis and secretion in adipocytes. Finally, another cholesterol-binding drug, filipin, also induced MCP-1 secretion without altering membrane cholesterol level. Interestingly, both MβCD and filipin disturbed the integrity of lipid rafts, the membrane microdomains enriched in cholesterol. Thus, the depletion of membrane cholesterol in obese adipocytes may result in dysfunction of lipid rafts, leading to the elevation of proinflammatory signaling and MCP-1 secretion in adipocytes.
authors.affiliation: Department of Physiology and Pharmacology, Chang Gung University, Taoyuan, Taiwan.|Graduate Institute of Biomedical Sciences, Chang Gung University, Taoyuan, Taiwan.|Division of Endocrinology and Metabolism, Department of Internal Medicine, Chang Gung Memorial Hospital, Linkou, Taiwan.
authors.forename: Juu-Chin
authors.identifier: http://orcid.org/0000-0001-8523-6992
authors.initials: JC
authors.lastname: Lu
authors.affiliation: Graduate Institute of Biomedical Sciences, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Yu-Ting
authors.initials: YT
authors.lastname: Chiang
authors.affiliation: Department of Physiology and Pharmacology, Chang Gung University, Taoyuan, Taiwan.|Graduate Institute of Biomedical Sciences, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Yu-Chun
authors.initials: YC
authors.lastname: Lin
authors.affiliation: Department of Physiology and Pharmacology, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Yu-Tzu
authors.initials: YT
authors.lastname: Chang
authors.affiliation: Department of Physiology and Pharmacology, Chang Gung University, Taoyuan, Taiwan.|Graduate Institute of Biomedical Sciences, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Chia-Yun
authors.initials: CY
authors.lastname: Lu
authors.affiliation: Department of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Tzu-Yu
authors.initials: TY
authors.lastname: Chen
authors.affiliation: Graduate Institute of Biomedical Sciences, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Chia-Shan
authors.initials: CS
authors.lastname: Yeh
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology / Q000378:metabolism*; D000818:Animals; D002454:Cell Differentiation; D018932:Chemokine CCL2 / Q000378:metabolism*; D002784:Cholesterol / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D021962:Membrane Microdomains / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D015398:Signal Transduction; D047392:beta-Cyclodextrins / Q000494:pharmacology
chemical_list: C491768:Ccl2 protein, mouse; D018932:Chemokine CCL2; D016328:NF-kappa B; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D002784:Cholesterol