期刊
TOXICOLOGICAL SCIENCES
卷 115, 期 2, 页码 482-491出版社
OXFORD UNIV PRESS
DOI: 10.1093/toxsci/kfq052
关键词
TCDD; TNF-alpha; adipocytes; insulin resistance; AhR
类别
资金
- Japan Society for the Promotion of Science [21780125]
- Ministry of Education, Culture, Sports, Science, and Technology of Japan [F031]
- Grants-in-Aid for Scientific Research [21780125] Funding Source: KAKEN
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) causes a wasting syndrome characterized by a loss of body weight accompanied by a decrease in adipose tissue weight, i.e., insulin resistance-like symptoms. Therefore, the effects of TCDD on an insulin signaling pathway in mature 3T3-L1 adipocytes were investigated to obtain insight into the underlying mechanisms. TCDD downregulated expression of insulin receptor beta-subunit (IR beta), insulin receptor substrate 1 (IRS1), and glucose transporter 4 (GLUT4) and decreased insulin-stimulated glucose uptake activity. TCDD also upregulated expression of TNF-alpha, one of insulin resistance-inducing factors. Anti-TNF-alpha neutralization antibody and silencing of TNF-alpha receptor 1 (TNFR1) diminished the TCDD-induced downregulation of IR beta, IRS1, and GLUT4. Moreover, the experiments using small interfering RNA for an aryl hydrocarbon receptor (AhR) revealed that the TCDD-evoked changes of IR beta, IRS1, GLUT4, and TNF-alpha were dependent on AhR. TCDD also stimulated the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 and c-Jun N-terminal kinase (JNK), and their inhibitors abrogated the TCDD-induced downregulation of IR beta, IRS1, and GLUT4; upregulation of TNF-alpha; and activation of NF-kappa B. Taken together, TCDD stimulates expression and secretion of TNF-alpha in adipocytes through activation of AhR, ERK1/2, and JNK, and the secreted TNF-alpha causes the downregulation of IR beta, IRS1, and GLUT4 through TNFR1, resulting in insulin resistance.
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