Expression of IκBα in the nucleus of human peripheral blood T lymphocytes
Expression of IκBα in the nucleus of human peripheral blood T lymphocytes
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DOI：
10.1038/sj.onc.1202455
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发表时间：
1999-02-25
期刊：
影响因子：
8
通讯作者：
Alcami, J
中科院分区：
文献类型：
--
作者：
de Lera, TL;Folgueira, L;Alcami, J
根据目前的模型，I kappa Bα的抑制能力可能是通过Rel/NF-kappa B蛋白在胞浆中的滞留而介导的。然而，I kappa Bα也在细胞系的细胞核中被检测到，并在瞬时转染时过表达。为了更好地了解核I kappa Bα在生理环境中的潜在作用，我们分析了它在人外周血T淋巴细胞(PBL)核中的存在。我们通过免疫印迹、间接免疫荧光和电子显微镜等不同技术证明了I kappa Bα在PBL中的核定位。在静息细胞中检测到低水平的核I kappaBα，而在PMA激活后获得超诱导。I kappa Bα的核库表现出比胞浆I kappa Bα更高的稳定性，并且部分不依赖于蛋白质的重新合成。出乎意料的是，核I kappa Bα的存在并没有抑制NF-kappa B与DNA的结合，这种现象并不是由于核水平上I kappa Bβ的存在。免疫沉淀实验未能证明核I-kappa Bα和核因子-kappaB蛋白之间的联系。我们的结果表明，在静息和PMA激活的人PBL中，I-kappa Bα以一种明显不活跃的形式存在于细胞核中，不能破坏核因子-kappaB与DNA的结合。
According to current models the inhibitory capacity of I kappa B alpha would be mediated through the retention of Rel/NF-kappa B proteins in the cytosol. However, I kappa B alpha has also been detected in the nucleus of cell lines and when overexpressed by transient transfection. To gain better insight into the potential role of nuclear I kappa B alpha in a physiological context we have analysed its presence in the nucleus of human peripheral blood T lymphocytes (PBL). We demonstrate the nuclear localization of I kappa B alpha in PBL by different techniques: Western blot, indirect immunofluorescence and electron microscopy. Low levels of nuclear I kappa B alpha were detected in resting cells whereas a superinduction was obtained after PMA activation. The nuclear pool of I kappa B alpha showed a higher stability than cytosolic I kappa B alpha and was partially independent of the resynthesis of the protein. Unexpectedly, the presence of nuclear I kappa B alpha did not inhibit NF-kappa B binding to DNA and this phenomenon was not due to the presence of I kappa B beta at the nuclear level. Immunoprecipitation experiments failed to demonstrate an association between nuclear I kappa B alpha and NF-kappa B proteins. Our results demonstrate that in resting and PMA-activated human PBL, I kappa B alpha is present in the nucleus in an apparently inactive form unable to disrupt NF-kappa B binding from DNA.