大鼠肝细胞核来源的无细胞体系中肝细胞核因子4介导的转录激活作用
Transcriptional activation by hepatocyte nuclear factor-4 in a cell-free system derived from rat liver nuclei.
作者信息
Harish S, Khanam T, Mani S, Rangarajan P
机构信息
Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India.
出版信息
Nucleic Acids Res. 2001 Mar 1;29(5):1047-53. doi: 10.1093/nar/29.5.1047.
Hepatocyte nuclear factor-4 (HNF4) regulates gene expression by binding to direct repeat motifs of the RG(G/T)TCA sequence separated by one nucleotide (DR1). In this study we demonstrate that endogenous HNF4 present in rat liver nuclear extracts, as well as purified recombinant HNF4, activates transcription from naked DNA templates containing multiple copies of the DR1 element linked to the adenovirus major late promoter. Recombinant HNF4 also activates transcription from the rat cellular retinol binding protein II (CRBPII) promoter in vitro. The region between -105 and -63 bp of this promoter is essential for HNF-mediated transactivation. The addition of a peptide containing the LXXLL motif abolished HNF4-mediated transactivation in vitro suggesting that LXXLL-containing protein factor(s) are involved in HNF4-mediated transactivation in rat liver nuclear extracts. This is the first report on transactivation by HNF4 in a cell-free system derived from rat liver nuclei.
肝细胞核因子4（HNF4）通过与被一个核苷酸隔开的RG(G/T)TCA序列的直接重复基序（DR1）结合来调节基因表达。在本研究中，我们证明大鼠肝核提取物中存在的内源性HNF4以及纯化的重组HNF4，可激活来自含有与腺病毒主要晚期启动子相连的多个DR1元件拷贝的裸露DNA模板的转录。重组HNF4在体外也可激活大鼠细胞视黄醇结合蛋白II（CRBPII）启动子的转录。该启动子-105至-63 bp之间的区域对于HNF介导的反式激活至关重要。添加含有LXXLL基序的肽可在体外消除HNF4介导的反式激活，这表明含LXXLL的蛋白质因子参与了大鼠肝核提取物中HNF4介导的反式激活。这是关于HNF4在源自大鼠肝细胞核的无细胞系统中进行反式激活的首次报道。
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