TRANSCRIPTIONAL CONTROL ELEMENTS IN THE GIBBON APE LEUKEMIA VIRUS LTR

进行了研究，以精确定位转录 长末端重复序列（LTR）内的增强子元件 不同的巨猿白血病病毒（GALV）株并鉴定 与增强子区域结合的细胞因子。 1)我们已经证明， GALV LTR的增强子活性包含在12 bp的 45 bp重复DNA片段的序列。 2)使用核酸外切酶II和DNA酶I足迹技术， 已经鉴定出一种核因子， 123 bp增强子序列。 它存在于表达 GALV，而不是在表达GALV差的细胞。 3)我们已经证明了肿瘤促进剂佛波醇 肉豆蔻酸酯乙酸酯可以增强转录活性， 在各种淋巴样细胞系中GALV LTR为50-100倍。 它还 增强其他几种病毒转录因子的表达， 元件包括SV 40，人T细胞嗜淋巴细胞病毒I型， 和劳斯肉瘤病毒，这表明它通过广义的 机制 出于实用目的，PMA提供了一个方便的 增加外源DNA在细胞中瞬时表达的方法 淋巴样细胞

Studies were undertaken to localize precisely the transcriptional enhancer elements within the long terminal repeats (LTRs) of different gibbon ape leukemia virus (GALV) strains and identify the cellular factor which binds to the enhancer region. 1) We have shown that the major element responsible for enhancer activity of the GALV LTR is contained within a 12 bp sequence of a 45 bp repeated DNA segment. 2) Using exonuclease II and DNAse I footprinting techniques we have identified a nuclear factor which binds specifically to the 123 bp enhancer sequence. It is present in cells which express GALV but not in cells which express GALV poorly. 3) We have demonstrated that the tumor promoter phorbol myristate acetate can enhance transcriptional activity of the GALV LTR 50-100 fold in various lymphoid cell lines. It also enhances expression of several other viral transcriptional elements including SV40, human T cell lymphotrophic virus type I, and Rous sarcoma virus, suggesting it works via a generalized mechanism. For practical purposes, PMA provides a convenient means for increasing transient expression of foreign DNA in lymphoid cells.