Consequences of mevalonate depletion - Differential transcriptional, translational, and post-translational up-reguiation of Ras, Rap1a, RhoA, and RhoB
Consequences of mevalonate depletion - Differential transcriptional, translational, and post-translational up-reguiation of Ras, Rap1a, RhoA, and RhoB
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DOI：
10.1074/jbc.m111369200
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发表时间：
2002-03-22
影响因子：
4.8
通讯作者：
Hohl, RJ
中科院分区：
文献类型：
--
作者：
Holstein, SA;Wohlford-Lenane, CL;Hohl, RJ
RAS相关蛋白是小的GTP酶，翻译后被甲氧戊酸衍生的异戊二烯类化合物修饰。尽管抑制异戊二烯基化对蛋白质功能的影响已经被研究，但异戊二烯样库的耗尽对异戊二烯基化蛋白表达的调节的后果还有待研究。在这些研究中，我们已经证明甲氧戊酸的耗竭会导致K562细胞中RAS、RAPIa、RhoA和RhoB的总水平增加。环己亚胺和[S-35]蛋氨酸脉冲/脉冲追逐实验表明，甲羟戊酸的耗竭增加了RAS和RhoA的从头合成，并减少了现有RAS和RhoA蛋白的降解。用放线菌素D预处理可完全阻止RhoB的诱导上调，但仅部分阻止RAS、RaplA和RhoA的上调。虽然甲氧戊酸的耗竭不会改变Ras mRNA的稳态水平，但RhoB mRNA的表达会增加。我们的结果首次证明，甲氧戊酸的耗竭通过包括转录、翻译和翻译后过程的调节在内的离散机制诱导RAS和RAS相关蛋白的上调。
Ras-related proteins are small GTPases that are post-translationally modified with mevalonate-derived isoprenoids. Although the effects of inhibition of isoprenylation on protein function have been examined, the consequences of depletion of isoprenoid pools on regulation of expression of isoprenylated proteins have yet to be investigated. In these studies we have shown that depletion of mevalonate results in increased total levels of Ras, Rap1a, RhoA, and RhoB in K562 cells. Cycloheximide and [S-35]methionine pulse/pulse-chase experiments reveal that mevalonate depletion increases the de novo synthesis of Ras and RhoA and decreases the degradation of existing Ras and RhoA protein. Pretreatment with actinomycin D completely prevents the induced up-regulation of RhoB and only partially prevents the up-regulation of Ras, Rapla, and RhoA. Although depletion of mevalonate does not alter steady state levels of Ras mRNA, there is an increase in RhoB mRNA Our results are the first to demonstrate that mevalonate depletion induces up-regulation of Ras and Ras-related proteins by discrete mechanisms that include modulation of transcriptional, translational, and post-translational processes.