McCaffrey P G, Goldfeld A E, Rao A
Division of Tumor Virology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115.
J Biol Chem. 1994 Dec 2;269(48):30445-50.
The tumor necrosis factor-alpha (TNF alpha) gene is an immediate early gene in activated T cells, in that it is rapidly induced without a requirement for protein synthesis. Maximal induction of TNF alpha mRNA can be induced by treatment of T cells with calcium ionophores alone, via a calcineurin-dependent process that is blocked by cyclosporin A. We have previously identified a promoter element, kappa 3, that is required for calcium-stimulated, cyclosporin A-sensitive induction of the TNF alpha gene in activated T cells. Here, we demonstrate that the kappa 3 binding factor contains NFATp, a cyclosporin-sensitive DNA-binding protein required for interleukin-2 gene transcription. NFATp binds to two sites within the kappa 3 element, and occupancy of both sites is required for TNF alpha gene induction. Thus, although the kappa 3 element has little sequence similarity to other NFATp-binding sites, it appears to function as a cyclosporin-sensitive promoter element in T cells by virtue of its ability to bind NFATp. The involvement of NFATp in transcriptional activation of both the interleukin-2 and TNF alpha genes suggests that this factor plays an important role in the coordinate induction of multiple cytokine genes, starting at the earliest stages of T cell activation.
肿瘤坏死因子-α（TNFα）基因是活化T细胞中的一个即早基因，即它在无需蛋白质合成的情况下即可被快速诱导。单独用钙离子载体处理T细胞，通过一种被环孢素A阻断的钙调神经磷酸酶依赖性过程，可诱导TNFα mRNA的最大程度表达。我们之前已鉴定出一个启动子元件κ3，它是活化T细胞中钙离子刺激的、对环孢素A敏感的TNFα基因诱导所必需的。在此，我们证明κ3结合因子包含NFATp，这是一种白细胞介素-2基因转录所需的对环孢素敏感的DNA结合蛋白。NFATp结合到κ3元件内的两个位点，且两个位点都被占据是TNFα基因诱导所必需的。因此，尽管κ3元件与其他NFATp结合位点的序列相似性很小，但由于其结合NFATp的能力，它似乎在T细胞中作为一个对环孢素敏感的启动子元件发挥作用。NFATp参与白细胞介素-2和TNFα基因的转录激活，这表明该因子在T细胞激活的最早阶段开始，在多种细胞因子基因的协同诱导中发挥重要作用。
