Herpes Simplex Virus Protein Kinases US3 and UL13 Modulate VP11/12 Phosphorylation, Virion Packaging, and Phosphatidylinositol 3-Kinase/Akt Signaling Activity
Herpes Simplex Virus Protein Kinases US3 and UL13 Modulate VP11/12 Phosphorylation, Virion Packaging, and Phosphatidylinositol 3-Kinase/Akt Signaling Activity
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DOI：
10.1128/jvi.00712-14
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发表时间：
2014-07-01
影响因子：
5.4
通讯作者：
Smiley, James R.
中科院分区：
文献类型：
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作者：
Eaton, Heather E.;Saffran, Holly A.;Smiley, James R.
磷脂酰肌醇3-激酶(PI3K)/Akt信号通路在多种细胞活动中发挥关键作用，促进细胞生长和存活。因此，大多数病毒修改这一途径以促进其复制和传播也就不足为奇了。以往的工作表明，单纯疱疹病毒1型(HSV-1)被膜蛋白VP11/12和US3蛋白激酶以相反的方式调控PI3K/Akt通路：VP11/12结合并激活Src家族激酶(SFK)，酪氨酸磷酸化，以SFK依赖的方式招募PI3K，并在HSV诱导的Akt活化残基上对Akt进行磷酸化；相反，US3抑制Akt的激活，并直接磷酸化下游的Akt靶点。我们研究了US3是否通过抑制VP11/12的信号活性来负向调节Akt。与这一假设一致，在US3缺失感染期间发生的Akt激活增强需要VP11/12，并与依赖SFK的VP11/12酪氨酸磷酸化增加相关。此外，删除US3导致几个VP11/12物种的相对丰度显著增加，这些物种在SDS-PAGE中迁移时迁移率降低。这些形式通过磷酸化产生，严格需要病毒UL13蛋白激酶，并被病毒粒子排除在外。综上所述，这些数据表明，US3抑制依赖SFK的酪氨酸和依赖UL13的VP11/12的丝氨酸/苏氨酸的磷酸化，从而抑制VP11/12的信号转导，促进VP11/12的病毒粒子包装。这些结果表明，病毒蛋白激酶介导的蛋白磷酸化事件协调了VP11/12作为病毒粒子成分和细胞内信号分子的作用。
The phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway plays key roles in diverse cellular activities and promotes cell growth and survival. It is therefore unsurprising that most viruses modify this pathway in order to facilitate their replication and spread. Previous work has suggested that the herpes simplex virus 1 (HSV-1) tegument proteins VP11/12 and US3 protein kinase modulate the PI3K/Akt pathway, albeit in opposing ways: VP11/12 binds and activates Src family kinases (SFKs), is tyrosine phosphorylated, recruits PI3K in an SFK-dependent fashion, and is required for HSV-induced phosphorylation of Akt on its activating residues; in contrast, US3 inhibits Akt activation and directly phosphorylates downstream Akt targets. We examined if US3 negatively regulates Akt by dampening the signaling activity of VP11/12. Consistent with this hypothesis, the enhanced Akt activation that occurs during US3-null infection requires VP11/12 and correlates with an increase in SFK-dependent VP11/12 tyrosine phosphorylation. In addition, deleting US3 leads to a striking increase in the relative abundances of several VP11/12 species that migrate with reduced mobility during SDS-PAGE. These forms arise through phosphorylation, strictly require the viral UL13 protein kinase, and are excluded from virions. Taken in combination, these data indicate that US3 dampens SFK-dependent tyrosine and UL13-dependent serine/threonine phosphorylation of VP11/12, thereby inhibiting VP11/12 signaling and promoting virion packaging of VP11/12. These results illustrate that protein phosphorylation events mediated by viral protein kinases serve to coordinate the roles of VP11/12 as a virion component and intracellular signaling molecule.