Ataxia-Telangiectasia, Mutated (ATM)/Nuclear Factor κ Light Chain Enhancer of Activated B Cells (NFκB) Signaling Controls Basal and DNA Damage-induced Transglutaminase 2 Expression
Ataxia-Telangiectasia, Mutated (ATM)/Nuclear Factor κ Light Chain Enhancer of Activated B Cells (NFκB) Signaling Controls Basal and DNA Damage-induced Transglutaminase 2 Expression
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DOI：
10.1074/jbc.m112.339317
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发表时间：
2012-05-25
影响因子：
4.8
通讯作者：
Brown, Kevin D.
中科院分区：
文献类型：
--
作者：
Ai, Lingbao;Skehan, Ryan R.;Brown, Kevin D.
转氨酶2（TG 2）是一种广泛表达的酶，其交联蛋白质，并且其与耐药表型相关的过表达通常在癌细胞中观察到。此外，TG 2表达的上调发生在对各种形式的细胞应激的响应期间;然而，驱动TG 2基因（TGM 2）的诱导型表达的分子机制需要阐明。在这里，我们表明，遗传毒性应激诱导TG 2表达通过共济失调毛细血管扩张，突变（ATM）/活化B细胞的核因子κ轻链增强子（NF κ B）信号通路。我们进一步证明了NF κ B B对于驱动培养细胞系中的组成型TG 2表达是必要且充分的。此外，ATM激酶的shRNA介导的敲低或药理学抑制导致组成型TG 2表达和NF κ B转录活性降低。我们记录了NF κ B B亚基p65（RelA）与TGM 2启动子内两个独立的共有NF κ B B结合位点相互作用，任何位点的突变或NF κ B B的药理学抑制都会降低TGM 2启动子活性，遗传毒性应激会促使p65与TGM 2启动子的高度关联。最后，我们观察到在表达重组TG 2的MDA-MB-468乳腺癌细胞中敲低p65或ATM部分降低了对阿霉素的抗性，表明与TG 2功能过表达相关的耐药性部分通过p65和ATM发挥作用。这项工作建立了一个新的ATM依赖性信号环，其中TG 2和NF κ B相互激活，导致NF κ B的持续激活和耐药表型的获得。
Transglutaminase 2 (TG2) is a ubiquitously expressed enzyme that cross-links proteins and its overexpression, linked to a drug resistant phenotype, is commonly observed in cancer cells. Further, up-regulation of TG2 expression occurs during response to various forms of cell stress; however, the molecular mechanisms that drive inducible expression of the TG2 gene (TGM2) require elucidation. Here we show that genotoxic stress induces TG2 expression through the Ataxia-Telangiectasia, Mutated (ATM)/Nuclear Factor kappa light chain enhancer of activated B cells (NF kappa B) signaling pathway. We further document that NF kappa B is both necessary and sufficient to drive constitutive TG2 expression in cultured cell lines. Additionally, shRNA-mediated knockdown or pharmacological inhibition of the ATM kinase results in reduced constitutive TG2 expression and NF kappa B transcriptional activity. We document that the NF kappa B subunit p65 (RelA) interacts with two independent consensus NF kappa B binding sites within the TGM2 promoter, that mutation of either site or pharmacological inhibition of NF kappa B reduces TGM2 promoter activity, and genotoxic stress drives heightened association of p65 with the TGM2 promoter. Finally, we observed that knockdown of either p65 or ATM in MDA-MB-468 breast cancer cells expressing recombinant TG2 partially reduces resistance to doxorubicin, indicating that the drug resistance linked to overexpression of TG2 functions, in part, through p65 and ATM. This work establishes a novel ATM-dependent signaling loop where TG2 and NF kappa B activate each other resulting in sustained activation of NF kappa B and acquisition of a drug-resistant phenotype.