MOLECULAR DETERMINANTS OF SENSITIVITY TO IFN IN CML

α-干扰素在15%的CML患者中诱导细胞遗传学缓解。 这些缓解与进化的可能性降低有关。 到了疾病的急变期。这项提议旨在 确定可能用来改变细胞周期的分子机制 髓系细胞对α-干扰素和细胞因子的反应性 敏感性或抵抗力的决定因素。对法律的监管 干扰素基因，它们的细胞作用，以及对 干扰素及其对干扰素诱导基因的影响 通过转录调节蛋白。其中包括IRF-1和 IRF-2，分别为正、负性调控因子的比值 它决定了细胞对激活的敏感性 干扰素信号转导途径。IRF-1已被证明与 干扰素基因的转录增强子和干扰素- 可诱导基因。此外，ISGF3pha和ISGF3-Gamma直接 参与干扰素诱导基因的转录激活 由α-干扰素引起。为了开发改变比率的方法 IRF-1和IRF-2在细胞内的表达，从而使细胞对 干扰素信号转导通路的激活，我们着手 基因5‘端转录调控区的克隆与分析 IRF-1和IRF-2基因的启动子。我们已经完成了克隆和 IRF-1基因及其5‘端启动子区(CHA，DNA)的全序列测定 和细胞生物学11：605-611,1992)。我们已经在功能上描述了 IRF-1基因转录启动子(SIMS，出版中，分子 和细胞生物学，1992)。我们已经克隆了IRF-2基因，并 目前其启动子的特征(Cha，1992)。此外，我们的 研究已经确定了一种细胞因素，它改变了 ISGF3之间形成的络合物的电泳迁移率 和IRF-1核调节蛋白及其转录增强子 干扰素诱导基因(Seong等人，JCI 86：1664-1770,1990)。 这是一种蛋白质二硫键异构酶(PDI)蛋白质(Johnson等人，JBC 267：14412-14417,1992年)，它在慢性粒细胞白血病细胞中升高，并且是 与干扰素敏感状态的改变有关(Howard et Al，布拉德76：1117-1130,1990)。最后，我们已经证明了持续时间 细胞对α-干扰素的反应程度是可以改变的 通过伽玛-干扰素预处理(Gao等人，提交，JBC，1992)。我们 建议通过以下方式扩展这些发现：(1)开发 改变ELL内IRF-1和IRF-2的比例以改变其 对干扰素途径的敏感性；(2)功能特征 与阿尔法状态改变相关的氧化还原蛋白- 干扰素敏感性；以及(3)表征伽马干扰素如何 导致细胞反应的大小和持续时间发生变化 到α-干扰素。这些研究将有助于我们理解 α-干扰素反应的机制，以确定分子 对α-干扰素的敏感性和耐药性的决定因素 为新的治疗策略奠定基础，以增强细胞 对α-干扰素反应和规避耐药性的敏感性。 这可能会将α-干扰素的好处扩大到更多的 慢性粒细胞白血病患者。

Alpha-interferon induces cytogenetic remissions in 15% of CML patients. These remissions are associated with a reduced probability of evolution to the blastic phase of the disease. this proposal is designed to identify molecular mechanisms which may be used to alter the responsiveness of myeloid cells to alpha-interferon and the cellular determinants of sensitivity or resistance. The regulation of the interferon genes, their cellular actions, and the sensitivity to interferon and its effect on interferon-inducible genes are mediated through transcriptional regulatory proteins. Among these are IRF-1 and IRF-2, positive and negative regulatory factors respectively, the ratio of which determines the sensitivity of the cell to activation of the interferon signal transduction pathway. IRF-1 has been shown to bind to the transcriptional enhancers of the interferon genes and the interferon- inducible genes. In addition, ISGF3alpha and ISGF3-gamma are directly involved in the transcriptional activation of interferon-inducible genes by alpha-interferon. In order to develop methods of altering the ratio of IRF-1 and IRF-2 within cells, therefore sensitizing the cells to activation of the interferon signal transduction pathway, we set out to clone and analyze the 5' transcriptional regulatory regions of the promoters of IRF-1 and IRF-2 genes. We have completed the cloning and total sequencing of the IRF-1 gene and its 5' promoter region (Cha, DNA and Cell Biology 11:605-611, 1992). We have functionally characterized the transcriptional promoter of the IRF-1 gene (Sims, In press, Molecular and Cellular Biology, 1992). We have cloned the IRF-2 gene and are currently characterizing its promoter (Cha, 1992). In addition, our studies have identified a cellular factor which alters the electrophoretic mobility of the complexes which form between the ISGF3 and IRF-1 nuclear regulatory proteins and the transcriptional enhancers of interferon-inducible genes (Seong et al, JCI 86:1664-1770, 1990). this is a protein disulfide isomerase (PDI) protein (Johnson et al, JBC 267:14412-14417, 1992) which is elevated in CML cells, and which is associated with altered states of sensitivity to interferon (Howard et al, Blood 76:1117-1130, 1990). finally, we have shown that the duration and magnitude of the cellular response to alpha-interferon can be altered by gamma-interferon pretreatment (Gao et al, Submitted, JBC, 1992). We are proposing to extend these findings by: (1) developing ways of altering the ratio of IRF-1 and IRF-2 within ells to alter their sensitivity to the interferon pathway; (2) functionally characterizing the redox protein which is associated with altered states of alpha- interferon sensitivity; and (3) characterizing how gamma-interferon induces a change in the magnitude and duration of the cellular response to alpha-interferon. These studies will help us to understand the mechanism of the alpha-interferon response, to identify the molecular determinants of the sensitivity and resistance to alpha-interferon, to lay the foundation for new therapeutic strategies to enhance cellular sensitivity to alpha-interferon response, and to circumvent resistance. This may extend the benefits of alpha-interferon to greater numbers of CML patients.