title: Regulation of adipocyte differentiation and insulin action with rapamycin.
abstract: Here, we demonstrated that inhibition of mTOR with rapamycin has negative effects on adipocyte differentiation and insulin signaling. Rapamycin significantly reduced expression of most adipocyte marker genes including PPARgamma, adipsin, aP2, ADD1/SREBP1c, and FAS, and decreased intracellular lipid accumulation in 3T3-L1 and 3T3-F442A cells, suggesting that rapamycin would affect both lipogenesis and adipogenesis. Contrary to the previous report that suppressive effect of rapamycin on adipogenesis is limited to the clonal expansion, we revealed that its inhibitory effect persisted throughout the process of adipocyte differentiation. Thus, it is likely that constitutive activation of mTOR might be required for the execution of adipogenic programming. In differentiated 3T3-L1 adipocytes, chronic treatment of rapamycin blunted the phosphorylation of AKT and GSK, which is stimulated by insulin, and reduced insulin-dependent glucose uptake activity. Taken together, these results suggest that rapamycin not only prevents adipocyte differentiation by decrease of adipogenesis and lipogenesis but also downregulates insulin action in adipocytes, implying that mTOR would play important roles in adipogenesis and insulin action.
authors.affiliation: School of Biological Sciences, Seoul National University, Seoul 151-742, Republic of Korea.
authors.forename: Hye Jin
authors.initials: HJ
authors.lastname: Cho
authors.forename: Jiyoung
authors.initials: J
authors.lastname: Park
authors.forename: Hyun Woo
authors.initials: HW
authors.lastname: Lee
authors.forename: Yun Sok
authors.initials: YS
authors.lastname: Lee
authors.forename: Jae Bum
authors.initials: JB
authors.lastname: Kim
mesh_terms: D016475:3T3 Cells; D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics; D002454:Cell Differentiation / Q000187:drug effects; D011416:Complement Factor D; D004268:DNA-Binding Proteins / Q000235:genetics; D015536:Down-Regulation / Q000187:drug effects; D007328:Insulin / Q000378:metabolism*; D050356:Lipid Metabolism; D051379:Mice; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics; D012697:Serine Endopeptidases / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D020123:Sirolimus / Q000494:pharmacology*; D051780:Sterol Regulatory Element Binding Protein 1; D058570:TOR Serine-Threonine Kinases; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000235:genetics
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D007328:Insulin; D047428:Protein Kinase Inhibitors; D018160:Receptors, Cytoplasmic and Nuclear; C497388:Srebf1 protein, mouse; D051780:Sterol Regulatory Element Binding Protein 1; D050656:Transcription Factor AP-2; D014157:Transcription Factors; D011494:Protein Kinases; C546843:mTOR protein, mouse; D058570:TOR Serine-Threonine Kinases; D012697:Serine Endopeptidases; D011416:Complement Factor D; C493491:complement factor D, mouse; D020123:Sirolimus