Salzberg S, Wreschner D H, Oberman F, Panet A, Bakhanashvili M
Mol Cell Biol. 1983 Oct;3(10):1759-65. doi: 10.1128/mcb.3.10.1759-1765.1983.
To screen for cells with different sensitivities to interferon (IFN), NIH 3T3 mouse fibroblasts were subcloned and examined for their response to IFN treatment. Of 30 clones tested, 2 appeared to be relatively resistant to IFN, since the replication of both vesicular stomatitis virus and mengovirus was not inhibited, even in the presence of 1,000 U of IFN per ml. One resistant (A10) and one sensitive (A5) clone were further analyzed. In both clones, murine leukemia virus replication was equally inhibited by IFN, indicating the presence of functional receptors for IFN in the resistant clone. Using the (2'-5')oligoadenylate (2-5A) radiobinding assay, we could demonstrate that both clones contained the RNase L protein. Furthermore, this enzyme appears to be active, since a similar reduction in the rate of protein synthesis was evident after the introduction of exogenous 2-5A to the cells. We also analyzed the activity of another enzyme in the 2-5A pathway, namely, 2-5A synthetase. In the sensitive cells (A5), the induction of enzyme activity was proportional to the IFN concentration used, reaching a maximum of more than a 10-fold increase over the background of untreated cells. However, little if any induction over the basal activity was observed in the resistant cells (A10) when similar doses of IFN were used. It is thus probable that the lack of induction of 2-5A synthetase activity by IFN in A10 cells is at least partly responsible for their relative resistance to IFN treatment.
为筛选对干扰素（IFN）具有不同敏感性的细胞，对NIH 3T3小鼠成纤维细胞进行亚克隆，并检测它们对IFN处理的反应。在检测的30个克隆中，有2个似乎对IFN相对耐药，因为即使在每毫升含有1000 U IFN的情况下，水疱性口炎病毒和脑心肌炎病毒的复制也未受到抑制。进一步分析了一个耐药克隆（A10）和一个敏感克隆（A5）。在这两个克隆中，小鼠白血病病毒的复制均受到IFN的同等抑制，表明耐药克隆中存在功能性IFN受体。使用（2'-5'）寡腺苷酸（2-5A）放射性结合测定法，我们能够证明两个克隆均含有RNase L蛋白。此外，这种酶似乎具有活性，因为在向细胞中引入外源性2-5A后，蛋白质合成速率出现了类似的降低。我们还分析了2-5A途径中另一种酶即2-5A合成酶的活性。在敏感细胞（A5）中，酶活性的诱导与所用的IFN浓度成正比，在未处理细胞的背景基础上，最高增加超过10倍。然而，当使用相似剂量的IFN时，在耐药细胞（A10）中几乎未观察到比基础活性有任何诱导增加。因此，A10细胞中IFN未能诱导2-5A合成酶活性可能至少部分导致了它们对IFN处理的相对耐药性。
