Kaufman P A, Weinberg J B, Greene W C
Howard Hughes Medical Institute, Durham, North Carolina.
J Clin Invest. 1992 Jul;90(1):121-9. doi: 10.1172/JCI115824.
The nuclear factor (NF)-kappa B transcription factor system is composed of at least four inducible nucleoprotein adducts termed p50, p55 (NF-kappa B p50), p75 (NF-kappa B p65), and p85 (c-Rel). These proteins are expressed in the nuclei of activated T cells in a distinctly biphasic fashion, with p55 and p75 induction occurring within minutes whereas the induction of p50 and p85 occurs after several hours. In contrast, p50 and p55 are constitutively expressed in the nuclei of U937 and THP-1 monocytic cells. However, cellular activation is required for the nuclear expression of p75 in these cells. Additionally, activation of monocytic cells does not result in a significant induction of p85. Tumor necrosis factor alpha induces the nuclear expression of p55 and p75 in these monocytic cells within 20 min, presumably reflecting the liberation of these proteins from I kappa B. In contrast, phorbol myristate acetate (PMA) induces the expression of these proteins with delayed kinetics, raising the possibility that PMA is incapable of mediating the efficient release of p55 and p75 from I kappa B in these cells. These findings highlight important differences in the regulation of these proteins in monocytic cells versus T cells and suggest that the induced expression of NF-kappa B p65 in monocytes may play a central role in the activation of HIV-1 gene expression.
核因子（NF）-κB转录因子系统由至少四种可诱导的核蛋白加合物组成，分别称为p50、p55（NF-κB p50）、p75（NF-κB p65）和p85（c-Rel）。这些蛋白质在活化T细胞的细胞核中以明显的双相方式表达，p55和p75在数分钟内被诱导，而p50和p85的诱导则在数小时后发生。相比之下，p50和p55在U937和THP-1单核细胞的细胞核中组成性表达。然而，这些细胞中p75的核表达需要细胞活化。此外，单核细胞的活化不会导致p85的显著诱导。肿瘤坏死因子α在20分钟内诱导这些单核细胞中p55和p75的核表达，推测这反映了这些蛋白质从IκB中释放出来。相比之下，佛波酯肉豆蔻酸酯（PMA）以延迟的动力学诱导这些蛋白质的表达，这增加了PMA无法介导这些细胞中p55和p75从IκB中有效释放的可能性。这些发现突出了单核细胞与T细胞中这些蛋白质调节的重要差异，并表明单核细胞中NF-κB p65的诱导表达可能在HIV-1基因表达的激活中起核心作用。
