Moshier J A, Skunca M, Wu W, Boppana S M, Rauscher F J, Dosescu J
Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI 48201 USA.
Nucleic Acids Res. 1996 Mar 15;24(6):1149-57. doi: 10.1093/nar/24.6.1149.
The importance of ornithine decarboxylase (ODC) to cell proliferation is underscored by the complex array of cell-specific mechanisms invoked to regulate its synthesis and activity. Misregulation of ODC has severe negative consequences on normal cell function, including the acquisition of tumorigenic growth properties by cells overexpressing ODC. We hypothesize that ODC gene expression is a candidate target for the anti-proliferative function of certain tumor suppressors. Here we show that the Wilms' tumor suppressor WT1 binds to multiple sites within the human ODC promoter, as determined by DNase I protection and methylation interference assays. The expression of WT1 in transfected HCT 116, NIH/3T3 and HepG2 cells represses activity of the ODC promoter controlling expression of a luciferase reporter gene. In contrast WT1 expression enhances ODC promoter activity in SV40-transfected HepG2 cells. Both the extent of modulation of ODC gene expression and the mediating WT1 binding elements are cell specific. Constructs expressing WT1 deletion mutants implicate two regions required for repressor function, as well as an intrinsic activation domain. Understanding the regulation of ODC gene expression by WT1 may provide valuable insights into the roles of both WT1 and ODC in development and tumorigenesis.
鸟氨酸脱羧酶（ODC）对细胞增殖的重要性，通过一系列复杂的细胞特异性机制来调节其合成和活性得以凸显。ODC的调控异常对正常细胞功能具有严重的负面影响，包括过表达ODC的细胞获得致瘤生长特性。我们推测ODC基因表达是某些肿瘤抑制因子抗增殖功能的候选靶点。在此我们表明，通过DNA酶I保护和甲基化干扰实验确定，威尔姆斯肿瘤抑制因子WT1与人ODC启动子内的多个位点结合。在转染的HCT 116、NIH/３T3和HepG2细胞中WT1的表达抑制了控制荧光素酶报告基因表达的ODC启动子的活性。相反，WT1表达增强了SV40转染的HepG2细胞中ODC启动子的活性。ODC基因表达的调节程度和介导WT1结合的元件都是细胞特异性的。表达WT1缺失突变体的构建体表明了阻遏功能所需的两个区域以及一个内在激活域。了解WT1对ODC基因表达的调控可能为WT1和ODC在发育和肿瘤发生中的作用提供有价值的见解。
