POU1F1-Mediated Activation of hGH-N by Deoxyribonuclease I Hypersensitive Site II of the Human Growth Hormone Locus Control Region
POU1F1-Mediated Activation of hGH-N by Deoxyribonuclease I Hypersensitive Site II of the Human Growth Hormone Locus Control Region
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DOI：
10.1016/j.jmb.2011.11.001
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发表时间：
2012-01-06
影响因子：
5.6
通讯作者：
Shewchuk, Brian M.
中科院分区：
文献类型：
--
作者：
Hunsaker, Tamra L.;Jefferson, Holly S.;Shewchuk, Brian M.
人生长激素基因(hGH-N)由5个脱氧核糖核酸酶I超敏感位点(HSS)组成的远端基因座控制区(LCR)调控。围绕HSI和HSII的区域包含LCR的主要垂体生长激素特异性hGH-N激活功能。这种活性主要归因于HSI的POU1F1(Pit-1)元件，因为与HSI的连锁足以在转基因小鼠中适当调节hGH-N的表达，而HSII单独没有活性。然而，HSII和HSI的存在进一步增强了hGH-N的转基因表达，表明在HSII区域有更多的决定因素激活垂体hGH-N，但转基因模型和以前的体外系统的局限性阻碍了HSII的特征。在本研究中，我们使用了一种新的hGH-N调节域的微型染色体模型，并表明HSII在该系统中赋予hGH-N依赖于POU1F1的强大激活。伴随这一效应的是整个微染色体LCR/hGH-N结构域中依赖POU1F1的组蛋白乙酰化和甲基化。一系列体外DNA结合实验表明，POU1F1与HSII上的多个位点结合，与HSII功能中的直接作用一致。值得注意的是，POU1F1结合部分定位于灵长类特异的LINE-1(长散布核素1)反转录转座子的3‘非翻译区，这表明它在灵长类进化过程中的插入可能在垂体GH基因调控的背景下赋予了HSII区功能。这些观察阐明了HSII的功能，扩大了POU1F1在hGH LCR活性中的作用，并为LCR的分子进化提供了洞察力。(C)2011爱思唯尔有限公司。保留所有权利。
The human growth hormone gene (hGH-N) is regulated by a distal locus control region (LCR) composed of five deoxyribonuclease I hypersensitive sites (HSs). The region encompassing HSI and HSII contains the predominant pituitary somatotrope-specific hGH-N activation function of the LCR. This activity was attributed primarily to POU1F1 (Pit-1) elements at HSI, as linkage to HSI was sufficient for properly regulated hGH-N expression in transgenic mice, while HSII alone had no activity. However, the presence of HSII in conjunction with HSI further enhanced hGH-N transgene expression, indicating additional determinants of pituitary hGH-N activation in the HSII region, but limitations of transgenic models and previous ex vivo systems have prevented the characterization of HSII. In the present study, we employ a novel minichromosome model of the hGH-N regulatory domain and show that HSII confers robust POU1F1-dependent activation of hGH-N in this system. This effect was accompanied by POU1F1-dependent histone acetylation and methylation throughout the minichromosome LCR/hGH-N domain. A series of in vitro DNA binding experiments revealed that POU1F1 binds to multiple sites at HSII, consistent with a direct role in HSII function. Remarkably, POU1F1 binding, was localized in part to the 3' untranslated region of a primate-specific LINE-1 (long interspersed nuclear element 1) retrotransposon, suggesting that its insertion during primate evolution may have conferred function to the HSII region in the context of pituitary GH gene regulation. These observations clarify the function of HSII, expanding the role of POU1F1 in hGH LCR activity, and provide insight on the molecular evolution of the LCR. (C) 2011 Elsevier Ltd. All rights reserved.