NHC Key Laboratory of Hormones and Development, Tianjin Key Laboratory of Metabolic Diseases, Chu Hsien-I Memorial Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin 300134, China.
People's Hospital of Guangxi Zhuang Autonomous Region, China.
Dis Markers. 2022 Mar 14;2022:7553670. doi: 10.1155/2022/7553670. eCollection 2022.
Abundant evidence indicates that thyroid-stimulating hormone (TSH) levels are associated with insulin resistance in adipocytes. However, the potential mechanism of the association remains uncertain. The objective of this study was to determine the potential role of TSH in the suppression of insulin receptor substrate-1 (IRS-1) expression and IRS-1 tyrosyl phosphorylation, which might contribute to insulin resistance.
Mouse 3T3-L1 preadipocytes were differentiated into adipocytes. After treatment with 0.01, 0.1, and 1.0 mIU/ml bovine TSH, the TNF- concentration in the medium was determined by enzyme-linked immunosorbent assay (ELISA). Nuclear factor-kappa B (NF-B) DNA-binding activity was quantified by electrophoretic mobility shift assay (EMSA). IRS-1 levels in adipocytes were quantified by Western blotting, and tyrosine phosphorylation was measured by immunoprecipitation.
TSH induced TNF- secretion in a dose-dependent manner. There was a significant positive correlation between NF-B DNA-binding activity and TNF- secretion. This effect and correlation were weakened by BAY 11-7082 (a nuclear NF-B inhibitor) and H89 (an inhibitor of cyclic adenosine monophosphate- (cAMP-) dependent protein kinase A (PKA)). Treatment of cultured adipocytes with TSH inhibited insulin-stimulated IRS-1 tyrosyl phosphorylation but promoted TSH-dependent secretion of TNF- and activation of NF-B DNA-binding activity. The effects of TSH were significantly inhibited by BAY 11-7082 and H89 and were completely blocked by the TNF- antagonist WP9QY.
TSH inhibited IRS-1 protein expression and tyrosyl phosphorylation in 3T3-L1 adipocytes by stimulating TNF- production via promotion of NF-B DNA-binding activity. TSH might play a pivotal role in the development of insulin resistance.
大量证据表明，甲状腺刺激激素（TSH）水平与脂肪细胞中的胰岛素抵抗有关。然而，这种关联的潜在机制仍不确定。本研究旨在确定 TSH 在抑制胰岛素受体底物-1（IRS-1）表达和 IRS-1 酪氨酸磷酸化中的潜在作用，这可能有助于胰岛素抵抗的发生。
将小鼠 3T3-L1 前脂肪细胞分化为脂肪细胞。用 0.01、0.1 和 1.0 mIU/ml 牛 TSH 处理后，通过酶联免疫吸附试验（ELISA）测定培养基中 TNF-的浓度。通过电泳迁移率变动分析（EMSA）测定核因子-kappa B（NF-B）DNA 结合活性。通过 Western 印迹法测定脂肪细胞中 IRS-1 水平，通过免疫沉淀法测定酪氨酸磷酸化。
TSH 呈剂量依赖性诱导 TNF-分泌。NF-B DNA 结合活性与 TNF-分泌之间存在显著正相关。该作用和相关性被 BAY 11-7082（核 NF-B 抑制剂）和 H89（环磷酸腺苷-（cAMP-）依赖性蛋白激酶 A（PKA）抑制剂）减弱。用 TSH 处理培养的脂肪细胞可抑制胰岛素刺激的 IRS-1 酪氨酸磷酸化，但促进 TSH 依赖性 TNF-分泌和 NF-B DNA 结合活性的激活。TSH 的作用可被 BAY 11-7082 和 H89 显著抑制，并且被 TNF-拮抗剂 WP9QY 完全阻断。
TSH 通过刺激 TNF-产生来促进 NF-B DNA 结合活性，从而抑制 3T3-L1 脂肪细胞中 IRS-1 蛋白表达和酪氨酸磷酸化。TSH 可能在胰岛素抵抗的发生中发挥关键作用。
