Intrinsic transcriptional activation-inhibition domains of the polyomavirus enhancer binding protein 2 core binding factor α subunit revealed in the presence of the β subunit
Intrinsic transcriptional activation-inhibition domains of the polyomavirus enhancer binding protein 2 core binding factor α subunit revealed in the presence of the β subunit
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DOI：
10.1128/mcb.18.5.2444
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发表时间：
1998-05-01
影响因子：
5.3
通讯作者：
Ito, Y
中科院分区：
文献类型：
--
作者：
Kanno, T;Kanno, Y;Ito, Y
多瘤病毒增强子结合蛋白2/核心结合因子（PEBP 2/CBF）的一个成员由PEBP 2 α B1/AML 1（作为α亚基）和β亚基组成。它在确定的造血中起重要作用，并且经常涉及与白血病相关的染色体异常。在本研究中，我们报告了PEBP 2 α B1中用于DNA结合和转录激活的功能可分离的模块化结构。通过PEBP 2 α B1的Runt结构域的DNA结合受到相邻羧基末端区域的阻碍，并且这种抑制通过与β亚基的相互作用而减轻。利用报告基因分析系统，其中α和β亚基都需要实现强的反式激活，我们发现了PEBP 2 α B1中转录激活和抑制结构域的存在，这些结构域仅在β亚基存在时才明显。抑制性结构域使全长PEBP 2 α B1的完全反式激活电位保持在其最大电位以下。PEBP 2 α B1的反式激活结构域与酵母GAL 4 DNA结合结构域的融合赋予了反式激活潜力，但进一步加入抑制结构域降低了活性。这些结果表明，α亚基作为转录激活因子的活性受到分子内以及β亚基的调节。PEBP 2 α B1和β亚基通过不同于核定位信号的信号靶向核基质。此外，反式激活结构域本身能够与核基质结合，这意味着反式激活与核基质附着之间存在关系。
A member of the polyomavirus enhancer binding protein 2/core binding factor (PEBP2/CBF) is composed of PEBP2 alpha B1/AML1 (as the alpha subunit) and a beta subunit. It plays an essential role in definitive hematopoiesis and is frequently involved in the chromosomal abnormalities associated with leukemia. In the present study, we report functionally separable modular structures in PEBP2 alpha B1 for DNA binding and for transcriptional activation. DNA binding through the Runt domain of PEBP2 alpha B1 was hindered by the adjacent carboxyterminal region, and this inhibition was relieved by interaction with the beta subunit. Utilizing a reporter assay system in which both the alpha and beta subunits are required to achieve strong transactivation, we uncovered the presence of transcriptional activation and inhibitory domains in PEBP2 alpha B1 that were only apparent in the presence of the beta subunit. The inhibitory domain keeps the full transactivation potential of full-length PEBP2 alpha B1 below its maximum potential. Fusion of the transactivation domain of PEBP2 alpha B1 to the yeast GAL4 DNA-binding domain conferred transactivation potential, but further addition of the inhibitory domain diminished the activity. These results suggest that the activity of the alpha subunit as a transcriptional activator is regulated intramolecularly as well as by the beta subunit. PEBP2 alpha B1 and the beta subunit were targeted to the nuclear matrix via signals distinct from the nuclear localization signal. Moreover, the transactivation domain by itself was capable of associating with the nuclear matrix, which implies the existence of a relationship between transactivation and nuclear matrix attachment.