p53 modulates the activity of the GLI1 oncogene through interactions with the shared coactivator TAF9.
p53 modulates the activity of the GLI1 oncogene through interactions with the shared coactivator TAF9.
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DOI：
10.1016/j.dnarep.2015.06.006
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发表时间：
2015-10
期刊：
影响因子：
3.8
通讯作者：
Walterhouse D
中科院分区：
文献类型：
--
作者：
Yoon JW;Lamm M;Iannaccone S;Higashiyama N;Leong KF;Iannaccone P;Walterhouse D
GLI 1癌基因和p53肿瘤抑制基因在控制干细胞和肿瘤细胞数量的抑制环中起作用。由于GLI 1和p53都与共激活因子TATA结合蛋白相关因子9（TAF 9）相互作用，我们假设这些转录因子之间对癌细胞中TAF 9的竞争可能有助于抑制环，并直接影响GLI 1功能和细胞表型。我们发现，TAF 9与致癌GLI家族成员GLI 1和GLI 2相互作用，但在无细胞下拉试验中不与GLI 3相互作用，在横纹肌肉瘤和骨肉瘤细胞系中与GLI 1相互作用。去除GLI 1的TAF 9结合酸性α螺旋反式激活结构域导致GLI 1转化细胞的能力显著降低。然后，我们将消除TAF 9结合的点突变引入GLI 1（L1052 I），并将建立结合的点突变引入GLI 3（I1510 L）。野生型和突变体GLI蛋白结合TAF 9表现出增强的反式激活和细胞转化活性相比，那些没有。因此，GLI-TAF 9结合似乎对致癌活性很重要。然后，我们确定野生型p53是否通过隔离TAF 9下调GLI功能。我们发现，p53结合TAF 9的亲和力大于GLI 1，并且p53与GLI 1或GLI 2的共表达下调了GLI 1诱导的反式激活，这可以使用GLI 1或p53的突变形式来消除。这表明p53从GLI 1中螯合TAF 9，这可能有助于p53抑制GLI 1活性，并可能影响靶向癌症中GLI-TAF 9相互作用的药物的治疗成功。
The GLI1 oncogene and p53 tumor suppressor gene function in an inhibitory loop that controls stem cell and tumor cell numbers. Since GLI1 and p53 both interact with the coactivator TATA Binding Protein Associated Factor 9 (TAF9), we hypothesized that competition between these transcription factors for TAF9 in cancer cells may contribute to the inhibitory loop and directly affect GLI1 function and cellular phenotype. We showed that TAF9 interacts with the oncogenic GLI family members GLI1 and GLI2 but not GLI3 in cell-free pull-down assays and with GLI1 in rhabdomyosarcoma and osteosarcoma cell lines. Removal of the TAF9-binding acidic alpha helical transactivation domain of GLI1 produced a significant reduction in the ability of GLI1 to transform cells. We then introduced a point mutation into GLI1 (L1052I) that eliminates TAF9 binding and a point mutation into GLI3 (I1510L) that establishes binding. Wild-type and mutant GLI proteins that bind TAF9 showed enhanced transactivating and cell transforming activity compared with those that did not. Therefore, GLI-TAF9 binding appears important for oncogenic activity. We then determined whether wild-type p53 down-regulates GLI function by sequestering TAF9. We showed that p53 binds TAF9 with greater affinity than does GLI1 and that co-expression of p53 with GLI1 or GLI2 down-regulated GLI-induced transactivation, which could be abrogated using mutant forms of GLI1 or p53. This suggests that p53 sequesters TAF9 from GLI1, which may contribute to inhibition of GLI1 activity by p53 and potentially impact therapeutic success of agents targeting GLI-TAF9 interactions in cancer.