NR4A1 (Nur77) mediates thyrotropin-releasing hormone-induced stimulation of transcription of the thyrotropin β gene: analysis of TRH knockout mice.
NR4A1 (Nur77) mediates thyrotropin-releasing hormone-induced stimulation of transcription of the thyrotropin β gene: analysis of TRH knockout mice.
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DOI：
10.1371/journal.pone.0040437
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Mori M
中科院分区：
文献类型：
--
作者：
Nakajima Y;Yamada M;Taguchi R;Shibusawa N;Ozawa A;Tomaru T;Hashimoto K;Saito T;Tsuchiya T;Okada S;Satoh T;Mori M
促甲状腺激素释放激素 (TRH) 是垂体前叶促甲状腺激素刺激激素 (TSH) 合成的主要刺激剂，但 TRH 究竟如何刺激 TSHβ 基因仍不清楚。对甲状腺激素状态不同的 TRH 缺陷小鼠的分析表明，TRH 对于 TSHβ 基因的基础活性和对甲状腺激素的反应至关重要。对野生型小鼠、TRH 缺陷小鼠和甲状腺激素替代的 TRH 缺陷小鼠的垂体进行 cDNA 微阵列和 K 均值聚类分析，结果显示，在缺乏 TRH 和补充甲状腺激素的情况下，TSHβ 基因表现出最大且最一致的表达下降，NR4A1 基因属于同一簇 并显示出与 TSHβ 基因相似的表达谱。免疫组织化学分析表明，NR4A1不仅在ACTH和FSH产生细胞中表达，而且在促甲状腺细胞中表达，并且在TRH缺陷的垂体中表达显着降低。此外，体外实验表明，在 GH4C1 细胞中与 TRH 一起孵育，一小时内内源性 NR4A1 mRNA 水平增加了约 50 倍，并且这种刺激被 PKC 和 ERK1/2 抑制剂抑制。 Western blot分析证实TRH在2小时内增加了NR4A1的表达。启动子的一系列缺失表明 TSHβ 基因的 bp -138 和 +37 之间的区域负责 TRH 诱导的刺激，芯片分析表明 NR4A1 被招募到该区域。相反，通过 siRNA 敲低 NR4A1 会导致 TRH 诱导的 TSHβ 启动子活性显着降低。此外，TRH 通过 TRH 受体刺激 NR4A1 启动子活性。这些发现表明 1) TRH 是 TSHβ 基因的高度特异性调节剂，2) TRH 介导 TSHβ 基因的诱导，至少部分是通过 PKC 和 ERK1/2 途径顺序刺激 NR4A1-TSHβ 基因。
Thyrotropin-releasing hormone (TRH) is a major stimulator of thyrotropin-stimulating hormone (TSH) synthesis in the anterior pituitary, though precisely how TRH stimulates the TSHβ gene remains unclear. Analysis of TRH-deficient mice differing in thyroid hormone status demonstrated that TRH was critical for the basal activity and responsiveness to thyroid hormone of the TSHβ gene. cDNA microarray and K-means cluster analyses with pituitaries from wild-type mice, TRH-deficient mice and TRH-deficient mice with thyroid hormone replacement revealed that the largest and most consistent decrease in expression in the absence of TRH and on supplementation with thyroid hormone was shown by the TSHβ gene, and the NR4A1 gene belonged to the same cluster as and showed a similar expression profile to the TSHβ gene. Immunohistochemical analysis demonstrated that NR4A1 was expressed not only in ACTH- and FSH- producing cells but also in thyrotrophs and the expression was remarkably reduced in TRH-deficient pituitary. Furthermore, experiments in vitro demonstrated that incubation with TRH in GH4C1 cells increased the endogenous NR4A1 mRNA level by approximately 50-fold within one hour, and this stimulation was inhibited by inhibitors for PKC and ERK1/2. Western blot analysis confirmed that TRH increased NR4A1 expression within 2 h. A series of deletions of the promoter demonstrated that the region between bp -138 and +37 of the TSHβ gene was responsible for the TRH-induced stimulation, and Chip analysis revealed that NR4A1 was recruited to this region. Conversely, knockdown of NR4A1 by siRNA led to a significant reduction in TRH-induced TSHβ promoter activity. Furthermore, TRH stimulated NR4A1 promoter activity through the TRH receptor. These findings demonstrated that 1) TRH is a highly specific regulator of the TSHβ gene, and 2) TRH mediated induction of the TSHβ gene, at least in part by sequential stimulation of the NR4A1-TSHβ genes through a PKC and ERK1/2 pathway.
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影响因子：
--
作者：
Charles, Michael A.;Saunders, Thomas L.;Gordon, David F.
通讯作者：
Gordon, David F.
影响因子：
2.1
作者：
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通讯作者：
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影响因子：
3.5
作者：
Kakar, SS;Winters, SJ;Flynn, S
通讯作者：
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影响因子：
4.8
作者：
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通讯作者：
Ridgway, EC
影响因子：
4.1
作者：
Hashimoto, K;Yamada, M;Mori, M
通讯作者：
Mori, M