INTERFERON ACTION ON CELL STRUCTURE AND PROLIFERATION

干扰素（IFN）是细胞因子，已记录其在免疫调节中的功效。 毛细胞白血病的治疗，并显示出有希望的结果 在治疗肾细胞癌、慢性粒细胞性 白血病、肝炎和获得性免疫缺陷综合症。 的 拟议研究计划的目标是确定分子 IFN的抗增殖作用的基础，重点是 IFN α受体的表征; IFN α的拮抗作用 α与生长因子在信号转导水平的关系 和IFN α诱导的生长因子下调 受体表达 研究报告的基础 IFN的抗增殖作用是关键的辅助比较 分析干扰素对敏感和耐药Daudi和 肾癌细胞系均表达IFN受体。 这样的细胞系允许关键实验来鉴定特定的 IFN α抑制细胞增殖的机制 增殖 使用这样的细胞系，我们将定义 IFN α诱导的受体二聚化，高和低亲和力 结合成分和IFN α的糖基化部分 干扰素诱导的干扰素刺激基因（ISG）表达中的受体 以及诱导抗增殖和抗病毒活性。 基于我们最近的发现，IFN α刺激GTP结合 膜和抑制花生四烯酸（AA）释放IFN- 敏感但不耐药的细胞，我们假设这些细胞可能 是早期的，也许是强制性的步骤， α干扰素的作用。 GTP结合蛋白在干扰素中的作用 将调查激活ISG的行动， IFN的抗增殖作用。 我们认为干扰素阻断信号 由相关生长因子（EGF， PDGF、胰岛素等）。 我们将直接检查干扰素的作用 花生四烯酸（AA）释放，蛋白激酶C活性，和 在存在和不存在添加剂的情况下， 生长因子 干扰素对细胞功能的重要影响 只有在几个小时后才会显现出来。 基于我们 研究发现IFN-γ下调生长因子受体， α治疗减弱了细胞对这种免疫应答的能力， 我们将确定IFN是否调节生长因子 受体在转录和转录后的表达 转录水平。 我们将定义转录后 IFN α的作用，通过测量磷酸化和再循环 胰岛素，转铁蛋白和EGF受体的稳定性， 这些受体的mRNA。 我们计划确定 转录调控的研究， 特异性IFN-应答元件在5'区上游， EGF受体基因的起始位点。 这将使用 该基因的克隆片段和瞬时表达测定。 我们 也将决定是否有转录因子， 结合这些元素。

Interferons (IFNs) are cytokines that have documented efficacy in the treatment of hairy cell leukemia, and show promising results in the treatment of renal cell carcinoma, chronic myelocytic leukemia, hepatitis and acquired immune deficiency syndrome. The goal of the proposed research program is to define the molecular basis of the antiproliferative action of IFNs, focussing on characterization of the IFN alpha receptor; the antagonism of IFN alpha with growth factors at the level of signal transduction pathways; and IFN alpha-induced down-regulation of growth factor receptor expression. Studies of the basis for the antiproliferative action of IFN are critically aided by comparative analysis of the effects of IFN on sensitive and resistant Daudi and renal carcinoma cell lines all of which express IFN receptors. Such cell lines permit critical experiments to identify specific mechanisms underlying the inhibitory action of IFN alpha on cell proliferation. Using such cell lines, we will define the roles of IFN alpha-induced receptor dimerization, the high and low affinity binding components, and the glycosylated portion of the IFN alpha receptor in IFN-induced expression of IFN-stimulated genes (ISGs) and the induction of antiproliferative and antiviral activities. Based on our recent findings that IFN alpha stimulates GTP binding to membranes and depresses arachidonic acid (AA) release in IFN- sensitive but not in resistant cells, we hypothesize that these may be early and perhaps obligatory steps in the antiproliferative action of IFN alpha. The role of GTP-binding proteins in IFN action will be investigated in the activation of ISGs and the antiproliferative action of IFN. We propose that IFN blocks signal transduction pathways activated by relevant growth factors (EGF, PDGF, insulin, etc.). We will directly examine the effects of IFN on arachidonic acid (AA) release, protein kinase C activity, and membrane GTPase activity in the presence and absence of added growth factors. Some important effects of IFN on cell function become manifest only after a period of several hours. Based on our findings that down-regulation of growth factor receptors by IFN alpha treatment attenuates the ability of cells to respond to such factors, we will determine whether IFN modulates growth factor receptor expression at both transcriptional and post- transcriptional levels. We will define post-transcriptional effects of IFN alpha by measuring the phosphorylation and recycling of insulin, transferrin and EGF receptors, and the stability of the mRNA for these receptors. We plan to define the molecular basis of transcriptional regulation by determining whether there are specific IFN-responsive elements in the 5' region upstream from the start site of the EGF receptor gene. This will be done using cloned segments of this gene and transient expression assays. We will also determine whether there are transcription factors that bind such elements.