Chronic interleukin-6 (IL-6) treatment increased IL-6 secretion and induced insulin resistance in adipocyte: prevention by rosiglitazone.
IL-6 has emerged as an important cytokine upregulated in states of insulin resistance such as type 2 diabetes. We evaluated the chronic effect of IL-6 on insulin signaling in 3T3-F442A and 3T3-L1 adipocytes. First, cells responded to a chronic treatment with IL-6 by initiating an autoactivation process that increased IL-6 secretion. Second, IL-6-treated adipocytes showed a decreased protein expression of IR-beta subunit and IRS-1 but also an inhibition of the insulin-induced activation of IR-beta, Akt/PKB, and ERK1/2. Moreover, IL-6 suppressed the insulin-induced lipogenesis and glucose transport consistent with a diminished expression of GLUT4. IL-6-treated adipocytes failed to maintain their adipocyte phenotype as shown by the downregulation of the adipogenic markers FAS, GAPDH, aP2, PPAR-gamma, and C/EBP-alpha. IL-6 also induced the expression of SOCS-3, a potential inhibitor of insulin signaling. Finally, the effects of IL-6 could be prevented by rosiglitazone, an insulin-sensitizing agent. Thus, IL-6 may play an important role in the set-up of insulin resistance in adipose cell.
Lagathu
Claire
C
INSERM U.402 and IFR65 Saint-Antoine Faculty of Medicine, Paris, France.
Bastard
Jean-Philippe
JP
Auclair
Martine
M
Maachi
Mustapha
M
Capeau
Jacqueline
J
Caron
Martine
M
D016475:3T3 Cells; D041721:3T3-L1 Cells; D017667:Adipocytes / Q000187:drug effects* / Q000378:metabolism*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005947:Glucose / Q000378:metabolism*; D007333:Insulin Resistance / Q000502:physiology*; D015850:Interleukin-6 / Q000378:metabolism* / Q000494:pharmacology*; D051379:Mice; D011506:Proteins / Q000378:metabolism*; D012097:Repressor Proteins; D000077154:Rosiglitazone; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D045162:Thiazolidinediones / Q000494:pharmacology*; D014157:Transcription Factors; D015854:Up-Regulation / Q000187:drug effects* / Q000502:physiology
D015850:Interleukin-6; D011506:Proteins; D012097:Repressor Proteins; C491411:Socs3 protein, mouse; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D045162:Thiazolidinediones; D014157:Transcription Factors; D000077154:Rosiglitazone; D005947:Glucose