Asai T, Kambe F, Kikumori T, Seo H
Department of Endocrinology and Metabolism, Research Institute of Environmental Medicine, Nagoya University, Japan.
Biochem Biophys Res Commun. 1997 Jul 9;236(1):71-4. doi: 10.1006/bbrc.1997.6906.
Thyrotropin (TSH) induces the expression of fos and jun family genes in thyroid cells. The DNA-binding activity of these gene products (AP-1) has been shown to be enhanced by ubiquitous nuclear redox factor-1 (Ref-1). We thus examined whether TSH regulates Ref-1 gene expression in rat thyroid FRTL-5 cells. Northern blot analysis revealed that the abundance of Ref-1 mRNA significantly increased within 3 hours after TSH followed by a sustained increase until 12 hours. The increase was also induced by treatment with forskolin but not in the presence of cycloheximide, indicating that the TSH effect on Ref-1 mRNA is mediated by intracellular cAMP and requires de novo protein synthesis. Consistent with the elevation of the mRNA level, Western blot analysis showed an increase in Ref-1 protein 3 hours after TSH. The level continued to increase until 12 hours. These results suggested that increased Ref-1 by TSH might regulate the binding activity of AP-1 in thyroid cells. Considering that Ref-1 also has a DNA repair function, Ref-1 may play dual roles in gene regulation and DNA repair processes in thyroid cells.
促甲状腺激素（TSH）可诱导甲状腺细胞中fos和jun家族基因的表达。这些基因产物（AP-1）的DNA结合活性已被证明可被普遍存在的核氧化还原因子-1（Ref-1）增强。因此，我们研究了TSH是否调节大鼠甲状腺FRTL-5细胞中Ref-1基因的表达。Northern印迹分析显示，TSH处理后3小时内，Ref-1 mRNA的丰度显著增加，随后持续增加直至12小时。福斯高林处理也可诱导这种增加，但在放线菌酮存在的情况下则不会，这表明TSH对Ref-1 mRNA的作用是由细胞内cAMP介导的，并且需要从头合成蛋白质。与mRNA水平的升高一致，Western印迹分析显示TSH处理3小时后Ref-1蛋白增加。该水平持续增加直至12小时。这些结果表明，TSH诱导的Ref-1增加可能调节甲状腺细胞中AP-1的结合活性。考虑到Ref-1也具有DNA修复功能，Ref-1可能在甲状腺细胞的基因调控和DNA修复过程中发挥双重作用。
