Arginine methylation of BCL-2 antagonist of cell death (BAD) counteracts its phosphorylation and inactivation by Akt
Arginine methylation of BCL-2 antagonist of cell death (BAD) counteracts its phosphorylation and inactivation by Akt
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DOI：
10.1073/pnas.1015328108
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发表时间：
2011-04-12
影响因子：
11.1
通讯作者：
Fukamizu, Akiyoshi
中科院分区：
文献类型：
--
作者：
Sakamaki, Jun-ichi;Daitoku, Hiroaki;Fukamizu, Akiyoshi
蛋白质精氨酸甲基化是由蛋白质精氨酸甲基转移酶（PRMTs）家族催化的一种常见的翻译后修饰。我们以前报道过PRMT 1在Akt共有磷酸化基序（RxRxxS/T）内的两个精氨酸残基处甲基化Forkhead box O转录因子，并且这种甲基化阻断Akt介导的转录因子磷酸化。这些发现使我们假设精氨酸甲基化和磷酸化之间的功能串扰可以扩展到其他Akt靶蛋白以及Forkhead box O蛋白。在这里，我们确定BCL-2拮抗剂的细胞死亡（BAD）作为一个额外的底物PRMT 1之间的几个Akt靶蛋白。我们发现PRMT 1特异性结合并甲基化BAD的Arg-94和Arg-96，这两者都包含Akt共有磷酸化基序。与该假设一致，PRMT 1介导的这两个精氨酸残基的甲基化在体外和体内抑制Akt介导的BAD在Ser-99的磷酸化。我们还证明，BAD与14-3-3蛋白的复合物形成，发生在Akt介导的磷酸化之后，由PRMT 1负调控。此外，PRMT 1敲低阻止BAD的线粒体定位及其与抗凋亡BCL-XL蛋白的结合。BAD过表达导致凋亡增加，伴随着caspase-3的激活，而PRMT 1敲低显著抑制这些凋亡过程。总之，我们的研究结果增加了一个新的层面的复杂性翻译后BAD调控，并提供证据表明，精氨酸甲基化Akt共识磷酸化基序的功能作为一种抑制性修饰对Akt依赖的生存信号。
Protein arginine methylation is a common posttranslational modification catalyzed by a family of the protein arginine methyltransferases (PRMTs). We have previously reported that PRMT1 methylates Forkhead box O transcription factors at two arginine residues within an Akt consensus phosphorylation motif (RxRxxS/T), and that this methylation blocks Akt-mediated phosphorylation of the transcription factors. These findings led us to hypothesize that the functional crosstalk between arginine methylation and phosphorylation could be extended to other Akt target proteins as well as Forkhead box O proteins. Here we identify BCL-2 antagonist of cell death (BAD) as an additional substrate for PRMT1 among several Akt target proteins. We show that PRMT1 specifically binds and methylates BAD at Arg-94 and Arg-96, both of which comprise the Akt consensus phosphorylation motif. Consistent with the hypothesis, PRMT1-mediated methylation of these two arginine residues inhibits Akt-mediated phosphorylation of BAD at Ser-99 in vitro and in vivo. We also demonstrate that the complex formation of BAD with 14-3-3 proteins, which occurs subsequent to Akt-mediated phosphorylation, is negatively regulated by PRMT1. Furthermore, PRMT1 knockdown prevents mitochondrial localization of BAD and its binding to the antiapoptotic BCL-XL protein. BAD overexpression causes an increase in apoptosis with concomitant activation of caspase-3, whereas PRMT1 knockdown significantly suppresses these apoptotic processes. Taken together, our results add a new dimension to the complexity of posttranslational BAD regulation and provide evidence that arginine methylation within an Akt consensus phosphorylation motif functions as an inhibitory modification against Akt-dependent survival signaling.