Role of polyamines in p53-dependent apoptosis of intestinal epithelial cells
Role of polyamines in p53-dependent apoptosis of intestinal epithelial cells
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DOI：
10.1016/j.cellsig.2008.12.003
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发表时间：
2009-04-01
影响因子：
4.8
通讯作者：
Johnson, Leonard R.
中科院分区：
文献类型：
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作者：
Bhattacharya, Sujoy;Ray, Ramesh M.;Johnson, Leonard R.
虽然已知p53在胃肠道上皮细胞增殖中起关键作用，但Mdm2/p53通路对肠上皮细胞凋亡诱导剂的应答作用尚不清楚。我们的数据显示，喜树碱（CPT）诱导的凋亡与IEC-6细胞中p53、p21Cip1和Mdm2蛋白水平升高相关，同时ATR Ser428、p53 Ser15和Mdm2 Ser-166磷酸化水平升高。p53水平的升高及其磷酸化增加了Bax蛋白、caspase-9、-3的活化和细胞凋亡。然而，tnf - α / chx介导的细胞凋亡与p53蛋白水平和磷酸化无关。翻译抑制剂环己亚胺（CHX）。阻止cpt诱导的细胞凋亡CHX完全阻止cpt诱导的p53磷酸化和p21Cipl的合成。Bax和Bcl-xL蛋白不改变p53水平。p53激活剂RITA增强了cpt诱导的细胞凋亡。Mdm2拮抗剂Nutlin-3显著增加细胞凋亡，同时p53、Mdm2和p21Cip1蛋白水平升高。ATM/ATR激酶抑制剂CGK733可阻断cpt诱导的p53 Ser15磷酸化，并保护cpt诱导的细胞凋亡。用α -二氟甲基鸟氨酸（DFMO）抑制鸟氨酸脱羧酶（ODC）和随后的细胞内多胺的消耗增加了p53蛋白、Mdm2 Ser-166的磷酸化，并赋予了对cpt诱导的细胞凋亡的抗性。然而，多胺缺失对p53磷酸化没有影响。Nutlin-3逆转DFMO的保护作用，使细胞对cpt诱导的凋亡敏感。这些结果表明，多胺耗竭反应中p53的稳定和积累主要通过p21Cip1的表达调节细胞周期检查点，并抑制凋亡靶基因的转录。相反，p53在DNA损伤反应中的磷酸化和稳定化导致细胞凋亡，这表明p53在DNA损伤和多胺耗竭过程中发挥着不同的作用。(C) 2008爱思唯尔公司版权所有。
Although p53 is known to play a critical role in the proliferation of gastrointestinal epithelia, the role of the Mdm2/p53 pathway in response to inducers of apoptosis in intestinal epithelial cells is unknown. Our data show that camptothecin (CPT)-induced apoptosis correlated with increased p53, p21Cip1, and Mdm2 protein levels, with a simultaneous increase in ATR Ser428, p53 Ser15 and Mdm2 Ser-166 phosphorylation in IEC-6 cells. Increased p53 levels and its phosphorylation increased Bax protein, caspase-9, -3 activation and apoptosis. However, TNF-alpha/CHX-mediated apoptosis was independent of p53 protein levels and phosphorylation. The translation inhibitor, cycloheximide (CHX). prevented CPT-induced apoptosis. CHX completely prevented CPT-induced p53 phosphorylation and synthesis of p21Cipl. Bax and Bcl-xL proteins without altering p53 levels. The p53 activator, RITA, augmented CPT-induced apoptosis. The Mdm2 antagonist, Nutlin-3, significantly increased apoptosis, which was accompanied by increased p53, Mdm2 and p21Cip1 protein levels. The ATM/ATR kinase inhibitor, CGK733, blocked CPT-induced p53 Ser15 phosphorylation and protected cells from CPT-induced apoptosis. Inhibition of ornithine decarboxylase (ODC) with alpha-difluromethylornithine (DFMO) and subsequent depletion of intracellular polyamines increased p53 protein, Mdm2 Ser-166 phosphorylation and conferred resistance to CPT-induced apoptosis. However, polyamine depletion had no effect on p53 phosphorylation. Nutlin-3 reversed the protective effect of DFMO and sensitized cells to CPT-induced apoptosis. These results suggest that p53 stabilization and accumulation in response to polyamine depletion predominantly modulate cell cycle checkpoints via p21Cip1 expression and inhibit transcription of target genes responsible for apoptosis. In contrast, phosphorylation and stabilization of p53 in response to DNA-damage lead to apoptosis, which indicates different roles of p53 during DNA damage and polyamine depletion. (C) 2008 Elsevier Inc. All rights reserved.