Sequestration of p53 in the cytoplasm by adenovirus type 12 E1B 55-kilodalton oncoprotein is required for inhibition of p53-mediated apoptosis.
Sequestration of p53 in the cytoplasm by adenovirus type 12 E1B 55-kilodalton oncoprotein is required for inhibition of p53-mediated apoptosis.
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12 型 E1B 腺病毒 55 千道尔顿癌蛋白将 p53 隔离在细胞质中，这是抑制 p53 介导的细胞凋亡所必需的。
DOI：
10.1128/jvi.77.24.13171-13181.2003
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发表时间：
2003
影响因子：
5.4
通讯作者：
Liao,Daiqing
中科院分区：
文献类型：
--
作者：
Zhao,LisaY;Liao,Daiqing
腺病毒E1 B 55-kDa蛋白是p53介导的反式激活和凋亡的有效抑制剂。所提出的机制包括通过直接E1 B-p53相互作用将E1 B阻遏结构域拴系到p53应答启动子。55-kDa蛋白质对p53的胞质隔离将对p53介导的效应施加额外的抑制。为了进一步研究细胞质螯合的p53在其抑制E1 B 55-kDa蛋白的作用，我们系统地研究了结构域的Ad 12 55-kDa蛋白和p53，支持他们的共定位在细胞质体，并表明，N-末端的反式激活结构域（p53）是必不可少的保留p53在细胞质体。氨基酸11至27的缺失或甚至点突变L22 Q/W23 S消除了p53对胞质体的定位，而p53的其他部分和C-末端结构域则是缺失的。这种胞质体不同于与某些蛋白质过度表达相关的侵袭体，因为它既不改变波形蛋白中间丝，也不与中心体或泛素相关。这种结构的形成对Ad 12 55-kDa蛋白的突变敏感。引人注目的是，突变S476/477 A附近的C末端的Ad 12 55-kDa蛋白消除了形成的胞质体。Ad 5 55-kDa蛋白中的等效残基被证明对其抑制p53的能力至关重要。事实上，不能形成胞质体的Ad 12 55-kDa突变体不能再抑制p53介导的作用。相反，Ad 12 55-kDa蛋白不抑制p53突变体L22 Q/W23 S介导的凋亡。最后，我们表明，E1 B仍然可以螯合p53，包含线粒体输入序列，从而可能阻止p53的本地化线粒体。因此，由E1 B 55-kDa蛋白质对p53的细胞质螯合在限制p53活性中起重要作用。
The adenovirus E1B 55-kDa protein is a potent inhibitor of p53-mediated transactivation and apoptosis. The proposed mechanisms include tethering the E1B repression domain to p53-responsive promoters via direct E1B-p53 interaction. Cytoplasmic sequestration of p53 by the 55-kDa protein would impose additional inhibition on p53-mediated effects. To investigate further the role of cytoplasmic sequestration of p53 in its inhibition by the E1B 55-kDa protein we systematically examined domains in both the Ad12 55-kDa protein and p53 that underpin their colocalization in the cytoplasmic body and show that the N-terminal transactivation domain (TAD) of p53 is essential for retaining p53 in the cytoplasmic body. Deletion of amino acids 11 to 27 or even point mutation L22Q/W23S abolished the localization of p53 to the cytoplasmic body, whereas other parts of TAD and the C-terminal domain of p53 are dispensable. This cytoplasmic body is distinct from aggresome associated with overexpression of some proteins, since it neither altered vimentin intermediate filaments nor associated with centrosome or ubiquitin. Formation of this structure is sensitive to mutation of the Ad12 55-kDa protein. Strikingly, mutation S476/477A near the C terminus of the Ad12 55-kDa protein eliminated the formation of the cytoplasmic body. The equivalent residues in the Ad5 55-kDa protein were shown to be critical for its ability to inhibit p53. Indeed, Ad12 55-kDa mutants that cannot form a cytoplasmic body can no longer inhibit p53-mediated effects. Conversely, the Ad12 55-kDa protein does not suppress p53 mutant L22Q/W23S-mediated apoptosis. Finally, we show that E1B can still sequester p53 that contains the mitochondrial import sequence, thereby potentially preventing the localization of p53 to mitochondria. Thus, cytoplasmic sequestration of p53 by the E1B 55-kDa protein plays an important role in restricting p53 activities.