The Barrett's antigen anterior gradient-2 silences the p53 transcriptional response to DNA damage
The Barrett's antigen anterior gradient-2 silences the p53 transcriptional response to DNA damage
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DOI：
10.1074/mcp.m300089-mcp200
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发表时间：
2004-06-01
影响因子：
7
通讯作者：
Hupp, TR
中科院分区：
文献类型：
--
作者：
Pohler, E;Craig, AL;Hupp, TR
食管上皮易受胆汁酸反流的损害，胆汁酸反流促进正常组织损伤，导致巴雷特上皮的发展。有一个选择压力突变p53在此癌前上皮，从而确定了生理相关的模型，发现新的调节p53通路。蛋白质组学技术被用来确定这样的p53调节因子，通过鉴定蛋白质，在巴雷特上皮过表达。在Barrett上皮中选择性表达的非常丰富的多肽被鉴定为前梯度-2。免疫化学方法证实，前梯度-2在巴雷特上皮中相对于来自同一患者的正常鳞状组织普遍上调。将前梯度-2基因转染到细胞中增强集落形成，类似于由HIS 175等位基因编码的突变致癌p53，表明前梯度-2可以作为存活因子发挥作用。前梯度2的C-末端10个氨基酸的缺失中和了该基因的殖民地增强活性，表明该结构域在增强细胞存活中的关键作用。前梯度-2的组成性过表达不改变未应激细胞的细胞周期参数，表明该基因不直接修饰细胞周期。然而，细胞过度表达前梯度-2衰减p53磷酸化在Ser 15和Ser 392和沉默p53反式激活功能在紫外线（UV）损伤的细胞。在UV损伤的细胞中，前梯度-2的C-末端10个氨基酸的缺失允许Ser 15处的磷酸化，这表明促进集落存活的C-末端基序也有助于抑制Ser 15激酶途径。这些数据确定前梯度2作为一种新的生存因子，其研究可能揭示细胞途径，削弱肿瘤抑制p53。M
The esophageal epithelium is subject to damage from bile acid reflux that promotes normal tissue injury resulting in the development of Barrett's epithelium. There is a selection pressure for mutating p53 in this preneoplastic epithelium, thus identifying a physiologically relevant model for discovering novel regulators of the p53 pathway. Proteomic technologies were used to identify such p53 regulatory factors by identifying proteins that were overexpressed in Barrett's epithelium. A very abundant polypeptide selectively expressed in Barrett's epithelium was identified as anterior gradient- 2. Immunochemical methods confirmed that anterior gradient- 2 is universally up- regulated in Barrett's epithelium, relative to normal squamous tissue derived from the same patient. Transfection of the anterior gradient- 2 gene into cells enhances colony formation, similar to mutant oncogenic p53 encoded by the HIS175 allele, suggesting that anterior gradient- 2 can function as a survival factor. Deletion of the C- terminal 10 amino acids of anterior gradient2 neutralizes the colony enhancing activity of the gene, suggesting a key role for this domain in enhancing cell survival. Constitutive overexpression of anterior gradient- 2 does not alter cell- cycle parameters in unstressed cells, suggesting that this gene is not directly modifying the cell cycle. However, cells overexpressing anterior gradient- 2 attenuate p53 phosphorylation at both Ser15 and Ser392 and silence p53 transactivation function in ultraviolet ( UV)- damaged cells. Deletion of the C- terminal 10 amino acids of anterior gradient- 2 permits phosphorylation at Ser15 in UVdamaged cells, suggesting that the C- terminal motif promoting colony survival also contributes to suppression of the Ser15 kinase pathway. These data identify anterior gradient2 as a novel survival factor whose study may shed light on cellular pathways that attenuate the tumor suppressor p53. M