IRFs Regulate Cell Cycle and Growth Inhibitory Genes in

IRF 调节细胞周期和生长抑制基因

• 批准号: 6675559
• 负责人: Charles E Egwuagu
• 金额: --
• 依托单位: NATIONAL EYE INSTITUTE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6675559
• 关键词: antineoplastics; apoptosis; cell line; cysteine endopeptidases; eye neoplasms; gene expression; genetically modified animals; interferon gamma; intermolecular interaction; laboratory mouse; lens disorder; neoplasm /cancer genetics; neoplasm /cancer immunology; neoplasm /cancer remission /regression; neoplastic growth; p53 gene /protein; retinoblastoma protein; simian virus 40; transcription factor; tumor antigens; tumor suppressor proteins

Two members of the Interferon regulatory factor (IRF) family, IRF-1 and ICSBP (Interferon consensus sequence binding protein) are tumor suppressors and have potent growth inhibitory effects on hematopoietic cells. We previously showed that that IRF-1 and ICSBP are differentially expressed in the mouse lens and that perturbation of their levels or spatial distribution in the developing lens inhibited lens growth. In this study, we investigated the molecular mechanisms underlying their growth inhibitory effects in lens cells. Coding sequence of murine IRF-1 or ICSBP was cloned into a mammalian expression vector and used to transfect the a-TN4-1 lens epithelial cell line. Stable transfectants were established by selection in hygromycin B. The effects of IRF-1 or ICSBP on lens cell growth, transcription of cell cycle, tumor suppressor, apoptosis, and growth inhibitory genes were examined by RNase protection assay, Western blotting, immunoprecipitation, in vitro proliferation assay and gel-shift assay. We show that both IRF-1 and ICSBP inhibite the growth of the lens cells and that the growth inhibitory effects are mediated by up-regulation of cell cycle regulatory proteins (p130, cyclin-dependent kinase inhibitors p21 & p27), apoptotic-proteins (caspase 1) and the tumor suppressor p53. Although the two IRFs exhibit overlapping functions, they also have distinct effects on the lens cells; whereas IRF-1 and ICSBP induce p21, ICSBP also enhance p27 and IRF-1 expression. Neither protein affected Rb, Bcl-2/w/x, Bak, Bax or Bad gene expression. We further show that induction of the apoptotic and growth regulatory proteins is mediated by IRF-1/ICSBP interactions with IFN responsive elements in promoters of these genes. We provide for the first time empirical evidence that JAK/STAT signaling pathways mediated by IRF-1 and ICSBP regulate proteins that are critical to lens growth and differentiation. Our data therefore suggest that this important family of transcription factors implicated in hematopoietic cell growth and differentiation may also play a role in controling lens growth and differentiation through their effects on the cell cycle and growth factors/cytokine signaling in the lens.

干扰素调节因子（IRF）家族的两个成员，IRF-1和ICSBP（干扰素共有序列结合蛋白）是肿瘤抑制因子，对造血细胞具有强效的生长抑制作用。我们先前表明，IRF-1和ICSBP在小鼠透镜中差异表达，并且它们在发育中的透镜中的水平或空间分布的扰动抑制了透镜的生长。在这项研究中，我们调查的分子机制，其生长抑制作用的透镜细胞。将鼠IRF-1或ICSBP的编码序列克隆到哺乳动物表达载体中，并用于转染α-TN 4 -1透镜上皮细胞系。通过在潮霉素B中选择建立稳定的转染子。通过RNA酶保护实验、Western印迹、免疫沉淀、体外增殖实验和凝胶迁移实验检测IRF-1或ICSBP对透镜细胞生长、细胞周期、肿瘤抑制基因、凋亡和生长抑制基因转录的影响。我们发现，IRF-1和ICSBP都抑制了透镜细胞的生长，并且生长抑制作用是通过上调细胞周期调节蛋白（p130，细胞周期蛋白依赖性激酶抑制剂p21和p27），促凋亡蛋白（caspase 1）和肿瘤抑制因子p53介导的。虽然这两个IRF表现出重叠的功能，但它们对透镜细胞也有不同的作用;而IRF-1和ICSBP诱导p21，ICSBP也增强p27和IRF-1的表达。两种蛋白均不影响Rb、Bcl-2/w/x、巴克、Bax或Bad基因表达。我们进一步表明，诱导的凋亡和生长调节蛋白介导的IRF-1/ICSBP与这些基因的启动子中的IFN反应元件的相互作用。我们首次提供了经验证据表明，JAK/STAT信号通路介导的IRF-1和ICSBP调节蛋白质是至关重要的透镜的生长和分化。因此，我们的数据表明，这一重要的家族的转录因子参与造血细胞的生长和分化，也可能发挥作用，控制透镜的生长和分化，通过其对细胞周期和生长因子/细胞因子信号在透镜。