Department of Physiology, McGill University, Montreal, Canada.
PLoS One. 2009 Dec 24;4(12):e8420. doi: 10.1371/journal.pone.0008420.
Signaling through MEK-->ERK1/2 and PI3 kinases is implicated in many aspects of cell physiology, including the survival of oxidant exposure. Oxidants play a role in numerous physiological and pathophysiological processes, many of which rely on transport in and out of the nucleus. However, how oxidative stress impacts nuclear trafficking is not well defined.
METHODOLOGY/PRINCIPAL FINDINGS: To better understand the effect of stress on nucleocytoplasmic trafficking, we exposed cells to the oxidant diethyl maleate. This treatment activated MEK-->ERK1/2 as well as PI3 kinase-->Akt cascades and triggered the inhibition of classical nuclear import. To define the molecular mechanisms that regulate nuclear transport, we examined whether MEK and PI3 kinase signaling affected the localization of key transport factors. Using recently developed tools for image acquisition and analysis, the subcellular distributions of importin-alpha, CAS, and nucleoporins Nup153 and Nup88 were quantified in different cellular compartments. These studies identified specific profiles for the localization of transport factors in the nucleus and cytoplasm, and at the nuclear envelope. Our results demonstrate that MEK and PI3 kinase signaling as well as oxidative stress control nuclear trafficking and the localization of transport components. Furthermore, stress not only induced changes in transport factor distribution, but also upregulated post-translational modification of transport factors. Our results are consistent with the idea that the phosphorylation of importin-alpha, CAS, Nup153, and Nup88, and the O-GlcNAc modification of Nup153 increase when cells are exposed to oxidant.
CONCLUSIONS/SIGNIFICANCE: Our studies defined the complex regulation of classical nuclear import and identified key transport factors that are targeted by stress, MEK, and PI3 kinase signaling.
MEK-->ERK1/2 和 PI3 激酶的信号传递涉及细胞生理学的许多方面，包括对氧化剂暴露的存活。氧化剂在许多生理和病理生理过程中发挥作用，其中许多过程依赖于进出核的运输。然而，氧化应激如何影响核转运尚不清楚。
方法/主要发现：为了更好地了解应激对核质转运的影响，我们使细胞暴露于氧化剂二乙基马来酸酯中。这种处理激活了 MEK-->ERK1/2 以及 PI3 激酶-->Akt 级联，并触发了经典核输入的抑制。为了定义调节核转运的分子机制，我们检查了 MEK 和 PI3 激酶信号是否影响关键转运因子的定位。使用最近开发的图像采集和分析工具，在不同的细胞区室中定量测定了进口蛋白-α、CAS 和核孔蛋白 Nup153 和 Nup88 的亚细胞分布。这些研究确定了转运因子在核和细胞质以及核膜中定位的特定模式。我们的结果表明，MEK 和 PI3 激酶信号以及氧化应激控制核转运和转运成分的定位。此外，应激不仅诱导转运因子分布的变化，而且还上调转运因子的翻译后修饰。我们的结果与以下观点一致，即当细胞暴露于氧化剂时，进口蛋白-α、CAS、Nup153 和 Nup88 的磷酸化以及 Nup153 的 O-GlcNAc 修饰增加。
结论/意义：我们的研究定义了经典核输入的复杂调节，并确定了应激、MEK 和 PI3 激酶信号靶向的关键转运因子。
