Identification of redox/repair protein Ref-1 as a potent activator of p53
Identification of redox/repair protein Ref-1 as a potent activator of p53
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DOI：
10.1101/gad.11.5.558
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发表时间：
1997-03-01
影响因子：
10.5
通讯作者：
Prives, C
中科院分区：
文献类型：
--
作者：
Jayaraman, L;Murthy, KGK;Prives, C
p53可以从细胞中分离出来，其形式对于结合DNA是惰性的，但可以通过磷酸化、抗体结合或短单链DNA而显著刺激。这表明在遗传毒性应激时，细胞可以将潜在的p53转化为对DNA结合有活性的p53。令人惊讶的是，我们观察到潜伏的p53在体外激活转录中与活性p53一样有效。我们发现，HeLa细胞核提取物可以刺激DNA结合潜在的p53，并已从他们纯化的p53刺激蛋白，我们已经确定是产品的Ref-1基因。有趣的是，Ref-1是一种双重功能蛋白，既可以调节许多蛋白质的氧化还原状态，又可以作为DNA修复（AIP）内切核酸酶发挥作用。我们观察到，氧化形式的全长和羧基末端截短的p53（p53 Δ 30），这是无活性的DNA结合，都是由Ref-1蛋白刺激。然而，在还原剂的存在下，Ref-1是全长p53而不是p53 Delta 30的极其有效的刺激剂。这些和额外的数据表明，Ref-1蛋白刺激p53的氧化还原依赖性和非依赖性的手段，并暗示它在p53调控的关键作用。重要的是，我们还确定了Ref-1可以在体内刺激p53反式激活。这是在细胞中鉴定的p53功能的非共价蛋白修饰剂的第一个例子。
p53 can be isolated from cells in a form that is inert for binding to DNA but that can be stimulated dramatically by phosphorylation, antibody binding, or short single strands of DNA. This suggests that upon genotoxic stress, cells can convert latent p53 to one that is active for DNA binding. Surprisingly, we observed that latent p53 is as effective in activating transcription in vitro as is active p53. We found that HeLa nuclear extracts can stimulate DNA binding by latent p53 and have purified from them a p53-stimulating protein that we have determined to be the product of the Ref-l gene. Interestingly, Ref-l is a dual function protein that can both regulate the redox state of a number of proteins and function as a DNA repair (AIP) endonuclease. We observed that oxidized forms of full-length and carboxy-terminally truncated p53 (p53 Delta 30), which are inactive for DNA binding, are both stimulated by the Ref-l protein. However, in the presence of reducing agent, Ref-l is an extremely potent stimulator of full-length p53 but not p53 Delta 30. These and additional data indicate that Ref-l protein stimulates p53 by both redox-dependent and -independent means and imply a key role for it in p53 regulation. Importantly, we have also determined that Ref-l can stimulate p53 transactivation in vivo. This is the first example of a noncovalent protein modifier of p53 function identified in cells.