Thyroid-Stimulating Hormone Inhibits Insulin Receptor Substrate-1 Expression and Tyrosyl Phosphorylation in 3T3-L1 Adipocytes by Increasing NF-κB DNA-Binding Activity

Figure 1

Effect of TSH on the DNA-binding activity of NF-κB in 3T3-L1 adipocytes. (a) Representative autoradiogram showing the NF-κB DNA-binding activity in each group. 1: the control, 2: the TSH concentration of 0.01 mIU/ml, 3: the TSH concentration of 0.1 mIU/ml, 4: the TSH concentration of 1 mIU/ml, 5: after H89; and 6: after BAY 11-7082. (b) NF-κB DNA-binding activity was significantly and dose-dependently upregulated in cells treated with different concentrations of TSH (0.01, 0.1, and 1 mIU/ml) compared with control cells (), especially in cells stimulated with 0.1 mIU/ml and 1 mIU/ml TSH (). (c) Effects of H89 on NF-κB DNA binding. (d) Effects of BAY 11-7082 on NF-κB DNA-binding. Cells cultured under the same conditions were pretreated with H89 (an inhibitor of cAMP-dependent PKA) or BAY 11-7082 (a nuclear NF-κB inhibitor). NF-κB DNA-binding activity was suppressed after treatment with H89 and BAY 11-7082. The DNA-binding activity of NF-κB was quantified by densitometric analysis. The band intensities were normalized relative to the internal control and background. The number 1 represents the control group; 2, 3, and 4 represent the 0.01, 0.1, and 1 mIU/ml TSH groups, respectively; and 5 and 6 represent the H89- and BAY 11-7082-pretreated groups, respectively. The data are presented as the from three independent experiments ( vs. the 1 mIU/ml TSH group).

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