PML/RARα fusion protein transactivates the tissue factor promoter through a GAGC-containing element without direct DNA association
PML/RARα fusion protein transactivates the tissue factor promoter through a GAGC-containing element without direct DNA association
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PML/RARα 融合蛋白通过含有 GAGC 的元件反式激活组织因子启动子，无需直接 DNA 关联
DOI：
10.1073/pnas.0915006107
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发表时间：
2010-02-23
影响因子：
11.1
通讯作者：
Xi, Xiaodong
中科院分区：
文献类型：
--
作者：
Yan, Jinsong;Wang, Kankan;Xi, Xiaodong
严重凝血病是急性早幼粒细胞白血病 (APL) 的一种危及生命的并发症，主要归因于 APL 细胞中响应早幼粒细胞白血病/视黄酸受体 α (PML/RAR α) 融合蛋白而调节的组织因子 (TF) 水平过高。这种调节的潜在分子机制仍然不明确。随着 U937-PR9 细胞系在 TF 启动子不同突变体的控制下稳定表达荧光素酶报告基因，荧光素酶和 ChIP 数据都允许将 PML/RAR α 响应序列定位在 TF 启动子先前未定义的区域中，位于位置 -230 至 -242，缺乏已知的哺乳动物转录因子结合位点。在该序列中，GAGC 基序（-235 至 -238）被证明是至关重要的，因为这些核苷酸的缺失或突变会损害 PML/RAR α 相互作用和启动子反式激活。然而，EMSA 结果表明，PML/RARa 不与包含 -230 至 -242 序列的 DNA 探针结合，从而排除了直接的 DNA 关联。突变实验进一步表明 TF 启动子的激活蛋白 1 (AP-1) 位点对于 PML/RAR α 调节是可有可无的。这项研究表明，PML/RAR α 通过与由 GAGC 基序和侧翼核苷酸组成的元件间接相互作用，反式激活 TF 启动子，与 AP-1 结合无关。
A severe coagulopathy is a life-threatening complication of acute promyelocytic leukemia (APL) and is ascribable mainly to the excessive levels of tissue factor (TF) in APL cells regulated in response to the promyelocytic leukemia/retinoic acid receptor alpha (PML/RAR alpha) fusion protein. The underlying molecular mechanisms for this regulation remain ill-defined. With U937-PR9 cell lines stably expressing luciferase reporter gene under the control of different mutants of the TF promoter, both luciferase and ChIP data allowed the localization of the PML/RAR alpha-responsive sequence in a previously undefined region of the TF promoter at position -230 to -242 devoid of known mammalian transcription factor binding sites. Within this sequence a GAGC motif (-235 to -238) was shown to be crucial because deletion or mutation of these nucleotides impaired both PML/RAR alpha interaction and promoter transactivation. However, EMSA results showed that PML/RARa did not bind to DNA probes encompassing the -230 to -242 sequences, precluding a direct DNA association. Mutational experiments further suggest that the activator protein 1 (AP-1) sites of the TF promoter are dispensable for PML/RAR alpha regulation. This study shows that PML/RAR alpha transactivates the TF promoter through an indirect interaction with an element composed of a GAGC motif and the flanking nucleotides, independent of AP-1 binding.