Differentiation driven changes in the dynamic organization of Basal transcription initiation.
Differentiation driven changes in the dynamic organization of Basal transcription initiation.
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DOI：
10.1371/journal.pbio.1000220
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发表时间：
2009-10
期刊：
影响因子：
9.8
通讯作者：
Vermeulen W
中科院分区：
文献类型：
--
作者：
Giglia-Mari G;Theil AF;Mari PO;Mourgues S;Nonnekens J;Andrieux LO;de Wit J;Miquel C;Wijgers N;Maas A;Fousteri M;Hoeijmakers JH;Vermeulen W
一种新的小鼠模型揭示了转录因子的动态行为在生物体的不同细胞之间可能存在很大差异。基于无细胞系统和体外培养的活细胞的研究支持这样的概念：许多细胞过程（例如转录起始）是高度动态的：单个蛋白质随机地与其底物结合并在反应完成后分解。这种动态性质允许转录快速适应不断变化的条件。然而，这种动态转录组织对于嵌入哺乳动物组织中的有丝分裂后细胞的适用程度尚不清楚。为了能够直接分析活体哺乳动物组织中的转录起始动力学，我们创建了表达荧光标记的 TFIIH 的敲入小鼠模型。令人惊讶的是，与在培养和增殖细胞中观察到的情况相反，嵌入其组织中的有丝分裂后小鼠细胞表现出强烈且持久的转录依赖性 TFIIH 固定化。这种固定化既是分化驱动的，也是发展依赖的。此外，尽管 TFIIH 非常静态地结合，但它可以重新动员以响应新的转录需求。体细胞不同细胞中这种不同的时空转录组织重新审视了普遍接受的高度动态的转录动力学框架概念，并展示了转录等基本过程如何在完整的生物体中以根本不同的方式组织起来，正如之前从体外研究中推断出的那样。公认的真核 mRNA 生产模型是转录因子大部分时间都在细胞核中扩散，以随机方式遇到基因启动子（它们的底物）并在很短的时间内与其结合。类似的操作方式已被接受为大多数染色质相关酶过程（转录、复制、DNA 损伤反应）内相互作用的范例。然而，尚不清楚这种行为是否确实是生物体中所有细胞的共同特征。为了回答这个问题，我们培育了一种基因敲入小鼠，它在所有细胞中表达荧光标记的转录因子 (TFIIH)，该因子在转录起始和 DNA 修复中发挥作用。这种新工具与定量成像技术相结合，使我们能够监测这种转录因子在几乎所有活体组织中的移动性。在这项研究中，我们发现，与上述范例相反，在高度分化的有丝分裂后细胞（如神经元、肝细胞和心肌细胞）中，TFIIH 在转录过程中有效地固定在染色质上，而在增殖细胞中，TFIIH 具有与培养细胞中相同的动态行为。我们的研究还指出，从体外或培养细胞系统获得的结果并不总是可以直接外推到整个生物体。更重要的是，这给转录领域的研究人员提出了一个问题：为什么有些细胞选择动态转录框架，而另一些细胞则选择静态框架？
A novel mouse model reveals that the dynamic behavior of transcription factors can vary considerably between different cells of an organism. Studies based on cell-free systems and on in vitro–cultured living cells support the concept that many cellular processes, such as transcription initiation, are highly dynamic: individual proteins stochastically bind to their substrates and disassemble after reaction completion. This dynamic nature allows quick adaptation of transcription to changing conditions. However, it is unknown to what extent this dynamic transcription organization holds for postmitotic cells embedded in mammalian tissue. To allow analysis of transcription initiation dynamics directly into living mammalian tissues, we created a knock-in mouse model expressing fluorescently tagged TFIIH. Surprisingly and in contrast to what has been observed in cultured and proliferating cells, postmitotic murine cells embedded in their tissue exhibit a strong and long-lasting transcription-dependent immobilization of TFIIH. This immobilization is both differentiation driven and development dependent. Furthermore, although very statically bound, TFIIH can be remobilized to respond to new transcriptional needs. This divergent spatiotemporal transcriptional organization in different cells of the soma revisits the generally accepted highly dynamic concept of the kinetic framework of transcription and shows how basic processes, such as transcription, can be organized in a fundamentally different fashion in intact organisms as previously deduced from in vitro studies. The accepted model of eukaryotic mRNA production is that transcription factors spend most of their time diffusing throughout the cell nucleus, encountering gene promoters (their substrate) in a random fashion and binding to them for a very short time. A similar modus operandi has been accepted as a paradigm for interactions within most of the chromatin-associated enzymatic processes (transcription, replication, DNA damage response). However, it is not known whether such behavior is indeed a common characteristic for all cells in the organism. To answer this question, we generated a knock-in mouse that expresses in all cells a fluorescently tagged transcription factor (TFIIH) that functions in both transcription initiation and DNA repair. This new tool, when combined with quantitative imaging techniques, allowed us to monitor the mobility of this transcription factor in virtually all living tissues. In this study, we show that, in contrast to the aforementioned paradigm, in highly differentiated postmitotic cells such as neurons, hepatocytes, and cardiac myocytes, TFIIH is effectively immobilized on the chromatin during transcription, whereas in proliferative cells, TFIIH has the same dynamic behavior as in cultured cells. Our study also points out that results obtained from in vitro or cultured cell systems cannot always be directly extrapolated to the whole organism. More importantly, this raises a question for researchers in the transcription field: why do some cells opt for a dynamic framework for transcription, whereas others exhibit a static one?
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影响因子：
64.5
作者：
Iben, S;Tschochner, H;Grummt, I
通讯作者：
Grummt, I
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影响因子：
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通讯作者：
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作者：
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作者：
Fousteri, Maria;Vermeulen, Wim;Mullenders, Leon H. F.
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