Acetylation-dependent regulation of MDM2 E3 ligase activity dictates its oncogenic function.
Acetylation-dependent regulation of MDM2 E3 ligase activity dictates its oncogenic function.
复制标题
DOI：
10.1126/scisignal.aai8026
复制
发表时间：
2017-02-14
影响因子：
7.3
通讯作者：
Wei W
中科院分区：
文献类型：
--
作者：
Nihira NT;Ogura K;Shimizu K;North BJ;Zhang J;Gao D;Inuzuka H;Wei W
在人类癌症中经常观察到致癌E3泛素连接酶鼠双微体2（MDM 2）的异常激活。通过泛素化肿瘤抑制蛋白p53，导致其蛋白酶体介导的破坏，MDM 2限制了p53的肿瘤抑制活性。另一方面，通过自身遍在化，MDM 2以自身为目标进行破坏并促进p53肿瘤抑制途径，这一过程可以被去遍在蛋白酶疱疹病毒相关遍在蛋白特异性蛋白酶（HAUSP）拮抗。我们研究了MDM 2底物特异性的调节，发现乙酰转移酶p300介导的MDM 2的乙酰化和稳定化是阻断自我泛素化的分子开关，从而将其E3连接酶活性转移到p53。在体外和癌细胞系中，p300介导的MDM 2在Lys 182和Lys 185上的乙酰化使HAUSP能够结合，推测是去泛素化，并稳定MDM 2。这种核定位信号结构域内的乙酰化降低了其与酸性结构域的相互作用，随后增加了MDM 2中酸性结构域和RING结构域之间的相互作用，使HAUSP能够与MDM 2中的酸性结构域结合，并将MDM 2活性从autoubiquitination转移到p53泛素化。然而，在通过暴露于依托泊苷的遗传毒性应激后，去乙酰化酶沉默调节蛋白1（SIRT 1）在Lys 182和Lys 185处使MDM 2去乙酰化，从而促进自身泛素化和较少的泛素化以及随后的p53降解，从而增加p53依赖性凋亡。因此，这项研究表明，动态乙酰化是一个分子开关在MDM 2底物特异性的调节，揭示了进一步的洞察MDM 2/p53细胞生存轴的翻译后调节。
Abnormal activation of the oncogenic E3 ubiquitin ligase murine double minute 2 (MDM2) is frequently observed in human cancers. By ubiquitinating the tumor suppressor p53 protein, which leads to its proteasome-mediated destruction, MDM2 limits the tumor-suppressing activity of p53. On the other hand, by ubiquitinating itself, MDM2 targets itself for destruction and promotes the p53 tumor suppressor pathway, a process that can be antagonized by the deubiquitinase herpesvirus-associated ubiquitin-specific protease (HAUSP). We investigated the regulation of MDM2 substrate specificity and found that acetyltransferase p300–mediated acetylation and stabilization of MDM2 are molecular switches that block self-ubiquitination, thereby shifting its E3 ligase activity toward p53. In vitro and in cancer cell lines, p300-mediated acetylation of MDM2 on Lys182 and Lys185 enabled HAUSP to bind, presumably deubiquitinate, and stabilize MDM2. This acetylation within the nuclear localization signal domain decreased its interaction with the acidic domain, subsequently increased the interaction between the acidic domain and RING domain in MDM2, enabled the binding of HAUSP to the acidic domain in MDM2, and shifted MDM2 activity from autoubiquitination to p53 ubiquitination. However, upon genotoxic stress through exposure to etoposide, the deacetylase sirtuin 1 (SIRT1) deacetylated MDM2 at Lys182 and Lys185, thereby promoting self-ubiquitination and less ubiquitination and subsequent degradation of p53, thus increasing p53-dependent apoptosis. Therefore, this study indicates that dynamic acetylation is a molecular switch in the regulation of MDM2 substrate specificity, revealing further insight into the posttranslational regulation of the MDM2/p53 cell survival axis.