Swamynathan S K, Nambiar A, Guntaka R V
Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri-Columbia, 65212, USA.
J Virol. 1997 Apr;71(4):2873-80. doi: 10.1128/JVI.71.4.2873-2880.1997.
We have previously reported on the cloning and characterization of chk-YB-2, a novel member of the Y-box family of proteins, that binds to the sequence 5'-GTACCACC-3' present on the noncoding strand of the Rous sarcoma virus (RSV) long terminal repeat (LTR) in a single-strand-specific manner. Here, we demonstrate that deletion or mutation of this motif not only eliminates chk-YB-2 binding in vitro but also down-regulates RSV LTR-driven transcription in avian cells. Selective abrogation of chk-YB-2 expression by using antisense oligonucleotides decreased RSV LTR-driven transcription in a promoter-specific manner. This inhibition was not observed when a reporter construct with a deletion in the chk-YB-2 binding site was used. Depletion of cellular chk-YB-2 by transfecting the cells with excess of its recognition sequence oligonucleotides also resulted in reduced transcription from the RSV LTR. Taken together, these results suggest that chk-YB-2 acts as an activator of LTR-promoted transcription in avian cells and that this activation is mediated primarily through the sequence 5'-GTACCACC-3'.
我们之前报道过chk-YB-2的克隆和特性分析，它是Y-box蛋白家族的一个新成员，能以单链特异性方式与劳斯肉瘤病毒（RSV）长末端重复序列（LTR）非编码链上的5'-GTACCACC-3'序列结合。在此，我们证明该基序的缺失或突变不仅消除了chk-YB-2在体外的结合，还下调了禽细胞中RSV LTR驱动的转录。通过使用反义寡核苷酸选择性消除chk-YB-2的表达，以启动子特异性方式降低了RSV LTR驱动的转录。当使用在chk-YB-2结合位点有缺失的报告构建体时，未观察到这种抑制作用。用过量的其识别序列寡核苷酸转染细胞来耗尽细胞中的chk-YB-2，也导致RSV LTR的转录减少。综上所述，这些结果表明chk-YB-2在禽细胞中作为LTR促进转录的激活因子，并且这种激活主要通过5'-GTACCACC-3'序列介导。
