Peripheral CLOCK Regulates Target-Tissue Glucocorticoid Receptor Transcriptional Activity in a Circadian Fashion in Man
Peripheral CLOCK Regulates Target-Tissue Glucocorticoid Receptor Transcriptional Activity in a Circadian Fashion in Man
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DOI：
10.1371/journal.pone.0025612
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发表时间：
2011-09-28
期刊：
影响因子：
3.7
通讯作者：
Kino, Tomoshige
中科院分区：
文献类型：
--
作者：
Charmandari, Evangelia;Chrousos, George P.;Kino, Tomoshige
背景和目标：循环皮质醇在“主”昼夜节律时钟的控制下每日波动，而后者的外周“从”对应物通过乙酰化调节局部糖皮质激素靶组织处糖皮质激素受体（GR）的转录活性。在本论文中，我们研究了CLOCK介导的GR乙酰化对人类外周组织对糖皮质激素敏感性的影响。设计和参与者：我们检测了10名健康受试者在上午8点和下午8点获得的外周血单个核细胞（PBMC）中GR乙酰化和GR，CLOCK相关和糖皮质激素反应基因的mRNA表达，以及在早晨获得并培养24小时，每6小时暴露于3小时氢化可的松脉冲的PBMC中。结果：外周血单个核细胞GR乙酰化水平在早晨高于晚上，反映了外周血循环皮质醇水平的反相波动。所有已知的糖皮质激素反应基因的测试，如预期的氢化可的松在非同步EBVL，然而，这些基因中的一些没有显示出预期的昼夜mRNA波动在体内PBMC。相反，在没有内源性糖皮质激素的情况下，它们的mRNA在离体培养的自然同步PBMC中以时钟和GR乙酰化依赖的方式振荡，这表明循环皮质醇可能会阻止体内某些糖皮质激素应答基因的昼夜GR乙酰化依赖效应。外周时钟介导的人GR的昼夜乙酰化可以作为靶组织，基因特异性的反调节机制的行动，每日波动的皮质醇，有效地降低组织敏感性糖皮质激素在早上和增加它在晚上。
Context and Objective: Circulating cortisol fluctuates diurnally under the control of the "master'' circadian CLOCK, while the peripheral "slave'' counterpart of the latter regulates the transcriptional activity of the glucocorticoid receptor (GR) at local glucocorticoid target tissues through acetylation. In this manuscript, we studied the effect of CLOCK-mediated GR acetylation on the sensitivity of peripheral tissues to glucocorticoids in humans.Design and Participants: We examined GR acetylation and mRNA expression of GR, CLOCK-related and glucocorticoid-responsive genes in peripheral blood mononuclear cells (PBMCs) obtained at 8 am and 8 pm from 10 healthy subjects, as well as in PBMCs obtained in the morning and cultured for 24 hours with exposure to 3-hour hydrocortisone pulses every 6 hours. We used EBV-transformed lymphocytes (EBVLs) as non-synchronized controls.Results: GR acetylation was higher in the morning than in the evening in PBMCs, mirroring the fluctuations of circulating cortisol in reverse phase. All known glucocorticoid-responsive genes tested responded as expected to hydrocortisone in non-synchronized EBVLs, however, some of these genes did not show the expected diurnal mRNA fluctuations in PBMCs in vivo. Instead, their mRNA oscillated in a Clock-and a GR acetylation-dependent fashion in naturally synchronized PBMCs cultured ex vivo in the absence of the endogenous glucocorticoid, suggesting that circulating cortisol might prevent circadian GR acetylation-dependent effects in some glucocorticoid-responsive genes in vivo.Conclusions: Peripheral CLOCK-mediated circadian acetylation of the human GR may function as a target-tissue, gene-specific counter regulatory mechanism to the actions of diurnally fluctuating cortisol, effectively decreasing tissue sensitivity to glucocorticoids in the morning and increasing it at night.