David M, Romero G, Zhang Z Y, Dixon J E, Larner A C
Division of Cytokine Biology, Center for Biologics Evaluation and Research, Bethesda, Maryland 20892.
J Biol Chem. 1993 Mar 25;268(9):6593-9.
Interaction of interferon alpha (IFN alpha) with its cell surface receptor rapidly activates the formation of the transcription complex ISGF3, which subsequently translocates to the nucleus and stimulates the expression of a variety of early response genes. We have recently developed a cell-free system where IFN alpha can activate the formation of ISGF3 in vitro. This system has enabled us to demonstrate that the component of the ISGF3 transcription complex which is modified by IFN alpha treatment (ISGF3 alpha) is membrane-associated and that its activation involves a protein kinase. Using a combination of specific tyrosine kinase and phosphatase inhibitors and monoclonal anti-phosphotyrosine antibodies we now are able to demonstrate that IFN alpha-activated transcription involves at least a two-step process where a membrane-associated tyrosine phosphatase and a tyrosine kinase lead to modification of ISGF3 alpha and subsequent formation of the complete complex. Furthermore, formation of the ISGF3 complex is specifically disrupted by protein tyrosine phosphatase and can be reversibly dissociated by the phosphotyrosine analogue phenylphosphate. The latter observation suggested that SH2 and/or SH3 domains may be required for the stable formation of this transcription complex.
干扰素α（IFNα）与其细胞表面受体相互作用可迅速激活转录复合物ISGF3的形成，该复合物随后转移至细胞核并刺激多种早期反应基因的表达。我们最近开发了一种无细胞系统，在该系统中IFNα能够在体外激活ISGF3的形成。此系统使我们能够证明，经IFNα处理而被修饰的ISGF3转录复合物组分（ISGF3α）与膜相关，且其激活涉及一种蛋白激酶。通过联合使用特异性酪氨酸激酶和磷酸酶抑制剂以及单克隆抗磷酸酪氨酸抗体，我们现在能够证明IFNα激活的转录至少涉及一个两步过程，其中一种膜相关酪氨酸磷酸酶和一种酪氨酸激酶导致ISGF3α的修饰以及随后完整复合物的形成。此外，ISGF3复合物的形成被蛋白酪氨酸磷酸酶特异性破坏，并且可被磷酸酪氨酸类似物苯磷酸盐可逆解离。后一观察结果表明，SH2和/或SH3结构域可能是该转录复合物稳定形成所必需的。
