INTERFERON-ALPHA REGULATES NUCLEAR TRANSLOCATION AND DNA-BINDING AFFINITY OF ISGF3, A MULTIMERIC TRANSCRIPTIONAL ACTIVATOR
INTERFERON-ALPHA REGULATES NUCLEAR TRANSLOCATION AND DNA-BINDING AFFINITY OF ISGF3, A MULTIMERIC TRANSCRIPTIONAL ACTIVATOR
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DOI：
10.1101/gad.4.10.1753
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发表时间：
1990-10-01
影响因子：
10.5
通讯作者：
LEVY, DE
中科院分区：
文献类型：
--
作者：
KESSLER, DS;VEALS, SA;LEVY, DE
干扰素-α的相互作用（IFN-α）具有特异性细胞表面受体的IFN-α-γ刺激依赖于一组IFN-α-γ的快速转录激活的生理变化。刺激基因（ISG）。干扰素刺激的反应元件（ISRE）是所有ISG的保守调节元件，是正调节因子干扰素刺激的基因因子-3（ISGF 3）转录激活的靶标。我们先前报道了IFN-α-IFN-γ细胞质中ISGF 3的翻译后活化。处理的细胞需要两种细胞质活性（ISFG 3 α.和ISGF 3 γ）。产生一种在细胞核中积累的ISRE结合复合物。在这项研究中，我们发现这些活动实际上是ISGF 3复合物的不同亚基，它们通过非共价相互作用相关联。细胞质ISGF 37 a和ISGF 3 γ的富集制剂的沉降分析、蛋白质复性和光亲和交联。和核ISGF 3的表达证实了ISGF 3 γ。是一个48 kD的多肽，具有内在的，低亲和力的DNA结合活性。48、84、91和113 kD的四种多肽在体外与ISRE结合;较大的三种多肽最可能组成ISGF 3 α。成分这些ISFG3.alpha。多肽不能单独结合DNA，但与ISGF 3 γ结合形成DNA结合复合物。所得异聚复合物具有与单个ISGF 3 γ相同的ISRE结合特异性。多肽，但25-倍的亲和力。而ISFG 3.在未刺激的细胞中，ISGF 37 a在细胞质和细胞核之间分配，仅在IF-α刺激后，ISGF 37 a才被刺激易位到细胞核。处理，导致两种ISGF 3 α的优先核积累。和ISGF 3 γ。作为稳定的ISGF 3-ISRE复合物。活化转录因子亚基的这种受调节的核转位维持IFN-α的特异性和快速性。信号通路
The interaction of interferon-.alpha. (IFN-.alpha.) with a specific cell-surface receptor elicits physiological changes that rely on rapid transcriptional activation of a group of IFN-.alpha.-stimulated genes (ISGs). The IFN-stimulated responses elements (ISRE), a conserved regulatory element of all ISGs, is the target for transcriptional activation by the positive regulator IFN-stimulated gene factor-3 (ISGF3). We reported previously that post-translational activation of ISGF3 in the cytoplasm of IFN-.alpha.-treated cells requires two cytoplasmic activities (ISFG3.alpha. and ISGF3.gamma.) to produce an ISRE-binding complex that accumulates in the nucleus. In ths study, we show that these activities are actually distinct subunits of the ISGF3 complex, which associate through noncovalent interaction. Sedimentation analysis, protein renaturation, and photoaffinity cross-linking of enriched preparations of cytoplasmic ISGF37a and ISGF3.gamma. and of nuclear ISGF3 demonstrated that ISGF3.gamma. was a 48-kD polypeptide with intrinsic, low-affinity DNA-binding activity. Tour polypeptides of 48, 84, 91, and 113 kD bound to the ISRE in vitro; the larger three polypeptides most likely compose the ISGF3.alpha. component. These ISFG3.alpha. polypeptides were unable to bind DNA alone but formed a DNA-binding complex in conjunction with ISGF3.gamma.. The resulting heteromeric complex had the same ISRE-binding specificity as the individual ISGF3.gamma. polypeptide but .apprx. 25-fold higher affinity. Whereas ISFG3.gamma. partitioned between the cytoplasm and nucleus in unstimulated cells, ISGF37a was stimulated to translocate to the nucleus only following IF-.alpha. treatment, resulting in preferential nucler accumulation of both ISGF3.alpha. and ISGF3.gamma. as a stable ISGF3-ISRE complex. This regulated nuclear translocation of an activated transcription factor subunit maintained the specificity and rapidity of the IFN-.alpha. signaling pathway.