Division of Biomedical Sciences, Mercer University School of Medicine, Macon, Georgia, USA.
Sci Rep. 2019 Jul 2;9(1):9523. doi: 10.1038/s41598-019-45825-5.
Epstein-Barr virus (EBV) latent membrane protein-1 (LMP1) activates numerous signal transduction pathways using its C-terminal activating regions. We reported that LMP1 increased global levels of sumoylated proteins, which aided the oncogenic nature of LMP1. Because increased protein sumoylation is detected in numerous cancers, we wanted to elucidate additional mechanisms by which LMP1 modulates the sumoylation machinery. Results indicated that SUMO-protease activity decreased in a LMP1-dependent manner, so we hypothesized that LMP1 inhibits SUMO-protease activity, resulting in reduced de-sumoylation of cellular proteins, which contributes to the detected accumulation of sumoylated proteins in EBV-positive lymphomas. Focusing on SENP2, findings revealed that LMP1 expression corresponded with increased sumoylation of SENP2 at K48 and K447 in a CTAR-dependent manner. Interestingly, independent of LMP1-induced sumoylation of SENP2, LMP1 also decreased SENP2 activity, decreased SENP2 turnover, and altered the localization of SENP2, which led us to investigate if LMP1 regulated the biology of SENP2 by a different post-translational modification, specifically ubiquitination. Data showed that expression of LMP1 inhibited the ubiquitination of SENP2, and inhibition of ubiquitination was sufficient to mimic LMP1-induced changes in SENP2 activity and trafficking. Together, these findings suggest that LMP1 modulates different post-translational modifications of SENP2 in order to modulate its biology and identify a third member of the sumoylation machinery that is manipulated by LMP1 during latent EBV infections, which can affect oncogenesis.
EB 病毒(EBV)潜伏膜蛋白 1(LMP1)通过其 C 端激活区域激活许多信号转导途径。我们报道 LMP1 增加了泛素化蛋白的整体水平,这有助于 LMP1 的致癌性质。由于在许多癌症中检测到蛋白质泛素化增加,我们希望阐明 LMP1 调节泛素化机制的其他机制。结果表明,SUMO 蛋白酶活性以 LMP1 依赖的方式降低,因此我们假设 LMP1 抑制 SUMO 蛋白酶活性,导致细胞蛋白去泛素化减少,这有助于解释 EBV 阳性淋巴瘤中检测到的泛素化蛋白积累。研究集中在 SENP2 上,发现 LMP1 表达与 SENP2 的 SUMO 化在 CTAR 依赖性方式下在 K48 和 K447 处增加相对应。有趣的是,独立于 LMP1 诱导的 SENP2 泛素化,LMP1 还降低 SENP2 活性,降低 SENP2 周转率并改变 SENP2 的定位,这导致我们研究 LMP1 是否通过另一种翻译后修饰,特别是泛素化,调节 SENP2 的生物学功能。数据表明,LMP1 的表达抑制了 SENP2 的泛素化,并且抑制泛素化足以模拟 LMP1 诱导的 SENP2 活性和运输变化。总之,这些发现表明 LMP1 调节 SENP2 的不同翻译后修饰,以调节其生物学功能,并确定 LMP1 在潜伏 EBV 感染期间操纵的泛素化机制的第三个成员,这可能会影响肿瘤发生。