A novel transcription regulatory complex containing death domain-associated protein and the ATR-X syndrome protein
A novel transcription regulatory complex containing death domain-associated protein and the ATR-X syndrome protein
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DOI：
10.1074/jbc.m401321200
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发表时间：
2004-05-07
影响因子：
4.8
通讯作者：
Yang, XL
中科院分区：
文献类型：
--
作者：
Tang, J;Wu, SB;Yang, XL
死亡结构域相关蛋白（Death domain associated protein，Daxx）是一种多功能的蛋白质，可调控细胞凋亡和转录。在细胞核内，Daxx是早幼粒细胞白血病蛋白（PML）核体（NB）的组分，并与许多转录因子相互作用，但其在转录中的确切作用仍然难以捉摸。为了进一步确定Daxx的功能，我们使用表位标记的亲和纯化分离了其在细胞核中的相互作用蛋白，并鉴定了X连锁精神发育迟滞和α-地中海贫血综合征蛋白（ATRX），该蛋白是在几种X连锁精神发育迟滞疾病中突变的ATP依赖性染色质重塑蛋白SNF 2家族的推定成员。我们发现，大量的内源性Daxx和ATRX存在于核复合物。Daxx通过其配对的两亲性α螺旋结构域与ATRX结合。ATRX具有由单核细胞体刺激的ATP酶活性，并且ATP酶结构域中的患者突变减弱该活性。当与启动子连接时，ATRX强烈抑制转录。Daxx不影响ATRX的ATP酶活性，但增强其转录抑制活性。此外，ATRX存在于PML-NB中，并且这种定位由Daxx介导。这些结果表明，ATRX.Daxx复合物是一种新型的ATP依赖性染色质重塑复合物，ATRX是核心ATP酶亚基，Daxx是靶向亚基。此外，ATRX定位于PML-NB支持这些结构可能在转录调控中起重要作用的概念。
Death domain-associated protein (Daxx) is a multifunctional protein that modulates both apoptosis and transcription. Within the nucleus, Daxx is a component of the promyelocytic leukemia protein (PML) nuclear bodies (NBs) and interacts with a number of transcription factors, yet its precise role in transcription remains elusive. To further define the function of Daxx, we have isolated its interacting proteins in the nucleus using epitope-tagged affinity purification and identified X-linked mental retardation and alpha-thalassaemia syndrome protein (ATRX), a putative member of the SNF2 family of ATP-dependent chromatin remodeling proteins that is mutated in several X-linked mental retardation disorders. We show that substantial amounts of endogenous Daxx and ATRX exist in a nuclear complex. Daxx binds to ATRX through its paired amphipathic alpha helices domains. ATRX has ATPase activity that is stimulated by mononucleosomes, and patient mutations in the ATPase domain attenuate this activity. ATRX strongly represses transcription when tethered to a promoter. Daxx does not affect the ATPase activity of ATRX, however, it alleviates its transcription repression activity. In addition, ATRX is found in the PML-NBs, and this localization is mediated by Daxx. These results show that the ATRX.Daxx complex is a novel ATP-dependent chromatin-remodeling complex, with ATRX being the core ATPase subunit and Daxx being the targeting subunit. Moreover, the localization of ATRX to the PML-NBs supports the notion that these structures may play an important role in transcription regulation.