Scott Kenneth L, Plon Sharon E
Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA.
Gene. 2005 Oct 10;359:119-26. doi: 10.1016/j.gene.2005.06.014.
Checkpoint Suppressor 1 (CHES1; FOXN3) encodes a member of the forkhead/winged-helix transcription factor family. The human CHES1 cDNA was originally identified by its ability to function as a high-copy suppressor of multiple checkpoint mutants of Saccharomyces cerevisiae. Accumulating expression profile data suggest that CHES1 plays a role in tumorigenicity and responses to cancer treatments, though nothing is known regarding the transcriptional function of CHES1 or other FOXN proteins in human cells. In this report, we find that the carboxyl terminus of CHES1 fused to a heterologous DNA binding domain consistently represses reporter gene transcription in cell lines derived from tumor tissues. Using a cytoplasmic two-hybrid screening approach, we find that this portion of CHES1 interacts with Ski-interacting protein (SKIP; NCoA-62), which is a transcriptional co-regulator known to associate with repressor complexes. We verify this interaction through co-immunoprecipitation experiments performed in mammalian cells. Further analysis of the CHES1/SKIP interaction indicates that CHES1 binds to a region within the final 66 hydrophobic residues of SKIP thus defining a new protein-protein interaction domain of SKIP. These data suggest that CHES1 recruits SKIP to repress genes important for tumorigenesis and the response to cancer treatments.
检查点抑制因子1(CHES1;FOXN3)编码叉头/翼状螺旋转录因子家族的一个成员。人类CHES1 cDNA最初是因其能够作为酿酒酵母多个检查点突变体的高拷贝抑制因子发挥作用而被鉴定出来的。越来越多的表达谱数据表明,CHES1在肿瘤发生和癌症治疗反应中发挥作用,尽管对于CHES1或其他FOXN蛋白在人类细胞中的转录功能尚不清楚。在本报告中,我们发现与异源DNA结合域融合的CHES1羧基末端在源自肿瘤组织的细胞系中持续抑制报告基因转录。使用细胞质双杂交筛选方法,我们发现CHES1的这一部分与Ski相互作用蛋白(SKIP;NCoA - 62)相互作用,SKIP是一种已知与抑制复合物相关的转录共调节因子。我们通过在哺乳动物细胞中进行的免疫共沉淀实验验证了这种相互作用。对CHES1/SKIP相互作用的进一步分析表明,CHES1与SKIP最后66个疏水残基内的一个区域结合,从而确定了SKIP的一个新的蛋白质 - 蛋白质相互作用结构域。这些数据表明,CHES1招募SKIP来抑制对肿瘤发生和癌症治疗反应重要的基因。