Transcriptional and translational control of Mcl-1 during apoptosis
Transcriptional and translational control of Mcl-1 during apoptosis
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DOI：
10.1016/s0003-9861(03)00345-x
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发表时间：
2003-09-15
影响因子：
3.9
通讯作者：
López, JM
中科院分区：
文献类型：
--
作者：
Iglesias-Serret, D;Piqué, M;López, JM
Mcl - 1是Bcl - 2家族的一个抗凋亡成员，其蛋白质和mRNA半衰期较短。在本研究中，我们研究了星形孢菌素和阿司匹林诱导的Mcl - 1蛋白质和mRNA表达的变化。这两种药物都能诱导Jurkat细胞凋亡，并降低Mcl - 1蛋白质水平。半胱天冬酶抑制剂Z - VAD.fmk和蛋白酶体抑制剂MG132部分保护Mcl - 1免于降解，表明在凋亡过程中半胱天冬酶依赖途径和蛋白酶体途径均参与其中。星形孢菌素还降低了Mcl - 1 mRNA水平，且这种降低主要是半胱天冬酶依赖的。此外，星形孢菌素对与荧光素酶基因报告基因融合的Mcl - 1启动子转录活性的降低程度大于放线菌素D（一种通用的转录抑制剂）。因此，我们得出结论：星形孢菌素以半胱天冬酶依赖的方式通过抑制转录来下调Mcl - 1 mRNA水平，并通过一种不依赖半胱天冬酶的转录后机制降低Mcl - 1蛋白质水平。相比之下，阿司匹林在诱导细胞活力丧失和Mcl - 1蛋白质降解的剂量和时间下，对Mcl - 1 mRNA水平没有影响。阿司匹林在半胱天冬酶激活之前迅速抑制新生蛋白质合成。此外，翻译因子eIF2α被瞬时磷酸化，因此在阿司匹林处理后很快被抑制。阿司匹林还抑制了几种连接的启动子构建体的荧光素酶报告基因活性，但不影响其mRNA 5'UTR中含有内部核糖体进入位点（IRES）的构建体的荧光素酶活性。我们得出结论：星形孢菌素抑制转录和翻译，而阿司匹林仅抑制依赖帽子结构的翻译。用环己酰亚胺处理，在抑制蛋白质合成但不影响细胞活力的剂量下，也诱导了Mcl - 1蛋白质降解。Mcl - 1的消失对于星形孢菌素和阿司匹林诱导凋亡可能是必要的，但不是充分的。提出了一个在药物诱导凋亡过程中Mcl - 1调控的模型。（C）2003爱思唯尔公司。保留所有权利。
Mcl-1 is an antiapoptotic member of the Bcl-2 family whose protein and mRNA have a short half-life. In this report, we studied the changes in Mcl-1 protein and mRNA expression induced by staurosporine and aspirin. Both drugs induced apoptosis in Jurkat cells and reduced the levels of Mcl-1 protein. The caspase inhibitor Z-VAD.fmk and the proteasome inhibitor MG132 partially protected Mcl-1 from decay, indicating that both caspase-dependent and proteasome pathways are involved during apoptosis. Staurosporine also reduced Mcl-1 mRNA levels and this reduction was mostly caspase-dependent. In addition, staurosporine reduced the transcriptional activity of the Mcl-1 promoter fused to a luciferase gene reporter more than actinomycin D, a general inhibitor of transcription. Thus, we conclude that staurosporine down-regulates Mcl-1 mRNA levels by inhibiting transcription in a caspase-dependent manner and reduces Mcl-1 protein levels by a caspase-independent post-transcriptional mechanism. In contrast aspirin, at doses and times that induced loss of viability and decay of Mcl-1 protein, had no effect on Mcl-1 mRNA levels. Aspirin rapidly inhibited de novo protein synthesis before caspase activation. Moreover, the translational factor eIF2alpha was transiently phosphorylated and therefore inhibited very soon after aspirin treatment. Aspirin also inhibited the luciferase reporter activity of several attached promoter constructs, but it did not affect the luciferase activity of a construct containing an internal ribosome entry site (IRES) in its mRNA 5'UTR. We conclude that staurosporine inhibits transcription and translation, whereas aspirin only inhibits cap-dependent translation. Treatment with cycloheximide, at doses that inhibit protein synthesis without affecting cell viability, also induced Mcl-1 protein decay. Mcl-1 disappearance might be necessary but not sufficient for the induction of apoptosis by staurosporine and aspirin. A model for the control of Mcl-1 during drug-induced apoptosis is presented. (C) 2003 Elsevier Inc. All rights reserved.