Laboratory of Nutritional Physiology, School of Food and Nutritional Sciences, The University of Shizuoka, Shizuoka 422-8526, Japan.
Biochem Biophys Res Commun. 2012 Apr 20;420(4):845-50. doi: 10.1016/j.bbrc.2012.03.085. Epub 2012 Mar 23.
Amphibian metamorphosis, which is controlled by thyroid hormone (TH), is highly temperature-sensitive. Using real-time PCR, we investigated the gene expression profile in the liver of Rana catesbeiana tadpoles kept at 28 and 4 °C and treated with 5 nM 3,3',5-triiodothyronine (T3). Out of the 48 genes tested, 12 were up-regulated at 4 °C in T3-treated or untreated tadpoles. These included genes involved in energy metabolism, transcription, and translation. Four TH-response genes, including TH receptor β (TRβ) gene, showed no response to T3 at 4 °C. Deiodinase III was the only gene down-regulated at 4 °C. Chromatin immunoprecipitation assays showed that CCAAT/enhancer-binding protein 2 gene activation by cold exposure was associated with an increase in the acetylation of histone H3 at lysine 9, whereas TRβ gene activation by T3 at 28 °C was associated with an increase in the methylation of histone H3 at lysine 36 with no T3-dependent changes in methylation states on cold exposure. Our results suggest that the transfer of TH signal to chromatin modifications on a primary early TH response gene was specifically blocked by exposure to cold.
两栖动物的变态发育受甲状腺激素（TH）的控制，对温度非常敏感。我们使用实时 PCR 技术，研究了在 28℃和 4℃下饲养的牛蛙蝌蚪肝脏中的基因表达谱，这些蝌蚪分别用 5 nM 3,3',5-三碘甲状腺原氨酸（T3）处理。在测试的 48 个基因中，有 12 个在 T3 处理或未处理的 4℃下的蝌蚪中上调。这些基因包括参与能量代谢、转录和翻译的基因。四个 TH 反应基因，包括 TH 受体 β（TRβ）基因，在 4℃时对 T3 没有反应。脱碘酶 III 是唯一在 4℃下调的基因。染色质免疫沉淀分析表明，低温暴露时 CCAAT/增强子结合蛋白 2 基因的激活与组蛋白 H3 赖氨酸 9 乙酰化的增加有关，而 T3 在 28℃时对 TRβ 基因的激活与组蛋白 H3 赖氨酸 36 甲基化的增加有关，但在低温暴露时没有 T3 依赖性的甲基化状态变化。我们的结果表明，TH 信号向主要的早期 TH 反应基因的染色质修饰的传递被低温暴露特异性阻断。
