REGULATION OF VIRAL AND CELLULAR GENE EXPRESSON

CBP/p300是几种转录因子的重要共激活因子 包括CREB、核激素受体、核因子-B和P53。近期 实验表明，CBP/p300通过 对染色质重塑的影响，但与基底的相互作用 转录因子也已被提出。分析CBP 转录激活，我们利用了体外转录 一种分析转录起始和转录的分析方法 在没有染色质效应的情况下重新启动。税项及附加费 CBP(氨基酸1-682)的N-末端片段体外结合 转录反应增加了全长和较短的 由启动和重新启动产生的抄本。CBP删除 缺失N端激活结构域的突变体为失活突变体。分析 税收与全长内源性CBP的相互作用表明 具有转录活性的TAX/CBP/RNA PolII复合体可以是 从细胞提取液中免疫沉淀。我们建议CBP激活 体内转录不仅通过其松动染色质结构实现 组蛋白乙酰化酶的功能，也是通过直接促进转录 通过税收响应性CREB绑定启动和重新启动。

CBP/p300 are important coactivators for several transcription factors including CREB, nuclear hormone receptors, NF- B and p53. Recent experiments suggest that CBP/p300 mediate gene activation through effects on chromatin remodeling, but interactions with basal transcription factors have also been proposed. To analyze CBP transcription activation, we have utilized an in vitro transcription assay that allows the analysis of transcription initiation and reinitiation in the absence of chromatin effects. Addition of Tax and a N-terminal fragment of CBP (amino acids 1-682) to the in vitro transcription reactions increased both full-length and shorter transcripts resulting from initiation and reinitiation. A CBP deletion mutant lacking the N-terminal activation domain was inactive. Analysis of the interaction of Tax with full-length endogenous CBP indicates that a transcriptionally active complex of Tax/CBP/RNA pol II can be immunoprecipitated from cell extracts. We propose that CBP activates transcription in vivo not only by loosening chromatin structure by its histone acetylase function, but also by directly promoting transcription initiation and reinitiation through Tax-responsive CREB binding.