Schmit Fabienne, Cremer Sarah, Gaubatz Stefan
Department of Physiological Chemistry I, Biocenter, University of Wuerzburg, Germany.
FEBS J. 2009 Oct;276(19):5703-16. doi: 10.1111/j.1742-4658.2009.07261.x. Epub 2009 Sep 2.
Recently, the conserved human LINC/DREAM complex has been described as an important regulator of cell cycle genes. LINC consists of a core module that dynamically associates with E2F transcription factors, p130 and the B-MYB transcription factor in a cell cycle-dependent manner. In this study, we analyzed the evolutionary conserved LIN54 subunit of LINC. We found that LIN54 is required for cell cycle progression. Protein interaction studies demonstrated that a predicted helix-coil-helix motif is required for the interaction of LIN54 with p130 and B-MYB. In addition, we found that the cysteine-rich CXC domain of LIN54 is a novel DNA-binding domain that binds to the cdc2 promoter in a sequence-specific manner. We identified two binding sites for LIN54 in the cdc2 promoter, one of which overlaps with the cell cycle homology region at the transcriptional start site. Gel shift assays suggested that, in quiescent cells, the binding of LIN54 at the cell cycle homology region is stabilized by the binding of E2F4 to the adjacent cell cycle-dependent element. Our data demonstrate that LIN54 is an important and integral subunit of LINC.
最近，保守的人类LINC/DREAM复合物被描述为细胞周期基因的重要调节因子。LINC由一个核心模块组成，该模块以细胞周期依赖性方式与E2F转录因子、p130和B-MYB转录因子动态结合。在本研究中，我们分析了LINC进化保守的LIN54亚基。我们发现LIN54是细胞周期进程所必需的。蛋白质相互作用研究表明，LIN54与p130和B-MYB相互作用需要一个预测的螺旋-螺旋-螺旋基序。此外，我们发现LIN54富含半胱氨酸的CXC结构域是一个新的DNA结合结构域，它以序列特异性方式与cdc2启动子结合。我们在cdc2启动子中鉴定出两个LIN54结合位点，其中一个与转录起始位点的细胞周期同源区域重叠。凝胶迁移实验表明，在静止细胞中，E2F4与相邻的细胞周期依赖性元件结合可稳定LIN54在细胞周期同源区域的结合。我们的数据表明LIN54是LINC的一个重要且不可或缺的亚基。
