邻苯二甲酸二(2-乙基己基)酯（DEHP）下调大鼠甲状腺组织和 FRTL-5 大鼠甲状腺细胞中的 Tshr 基因表达：甲状腺功能障碍的潜在机制。
DEHP Down-Regulates Tshr Gene Expression in Rat Thyroid Tissues and FRTL-5 Rat Thyrocytes: A Potential Mechanism of Thyroid Disruption.
机构信息
Seoul National University Hospital Healthcare System Gangnam Center, Seoul, Korea.
Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
出版信息
Endocrinol Metab (Seoul). 2021 Apr;36(2):447-454. doi: 10.3803/EnM.2020.920. Epub 2021 Mar 31.
BACKGROUND
Di-2-ethylhexyl phthalate (DEHP) is known to disrupt thyroid hormonal status. However, the underlying molecular mechanism of this disruption is unclear. Therefore, we investigated the direct effects of DEHP on the thyroid gland.
METHODS
DEHP (vehicle, 50 mg/kg, and 500 mg/kg) was administered to Sprague-Dawley rats for 2 weeks. The expression of the thyroid hormone synthesis pathway in rat thyroid tissues was analyzed through RNA sequencing analysis, quantitative reverse transcription-polymerase chain reaction (RT-PCR), and immunohistochemical (IHC) staining. DEHP was treated to FRTL-5 rat thyroid cells, and an RT-PCR analysis was performed. A reporter gene assay containing the promoter of thyroid stimulating hormone receptor (TSHR) in Nthy-ori 3-1 human thyroid cells was constructed, and luciferase activity was determined.
RESULTS
After DEHP treatment, the free thyroxine (T4) and total T4 levels in rats significantly decreased. RNA sequencing analysis of rat thyroid tissues showed little difference between vehicle and DEHP groups. In the RT-PCR analysis, Tshr expression was significantly lower in both DEHP groups (50 and 500 mg/kg) compared to that in the vehicle group, and IHC staining showed that TSHR expression in the 50 mg/kg DEHP group significantly decreased. DEHP treatment to FRTL-5 cells significantly down-regulated Tshr expression. DEHP treatment also reduced luciferase activity in a reporter gene assay for TSHR.
CONCLUSION
Although overall genetic changes in the thyroid hormone synthesis pathway are not clear, DEHP exposure could significantly down-regulate Tshr expression in thyroid glands. Down-regulation of Tshr gene appears to be one of potential mechanisms of thyroid disruption by DEHP exposure.
背景
邻苯二甲酸二（2-乙基己基）酯（DEHP）已知会破坏甲状腺激素状态。然而，这种破坏的潜在分子机制尚不清楚。因此，我们研究了 DEHP 对甲状腺的直接影响。
方法
将 DEHP（载体、50mg/kg 和 500mg/kg）给予 Sprague-Dawley 大鼠 2 周。通过 RNA 测序分析、定量逆转录聚合酶链反应（RT-PCR）和免疫组织化学（IHC）染色分析大鼠甲状腺组织中甲状腺激素合成途径的表达。用 DEHP 处理 FRTL-5 大鼠甲状腺细胞，并进行 RT-PCR 分析。构建含有促甲状腺激素受体（TSHR）启动子的报告基因测定 Nthy-ori 3-1 人甲状腺细胞，并测定荧光素酶活性。
结果
DEHP 处理后，大鼠游离甲状腺素（T4）和总 T4 水平明显下降。大鼠甲状腺组织的 RNA 测序分析显示，载体组和 DEHP 组之间差异不大。在 RT-PCR 分析中，与载体组相比，两个 DEHP 组（50mg/kg 和 500mg/kg）的 Tshr 表达明显降低，IHC 染色显示 50mg/kg DEHP 组 TSHR 表达明显降低。DEHP 处理 FRTL-5 细胞可显著下调 Tshr 表达。DEHP 处理还降低了 TSHR 的报告基因测定中的荧光素酶活性。
结论
尽管甲状腺激素合成途径的整体遗传变化尚不清楚，但 DEHP 暴露可显著下调甲状腺中的 Tshr 表达。Tshr 基因下调似乎是 DEHP 暴露破坏甲状腺的潜在机制之一。
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