Dynamic relocation of chromosomal protein HMG-17 in the nucleus is dependent on transcriptional activity
Dynamic relocation of chromosomal protein HMG-17 in the nucleus is dependent on transcriptional activity
复制标题
DOI：
10.1093/emboj/17.23.6992
复制
发表时间：
1998-12-01
期刊：
影响因子：
11.4
通讯作者：
Bustin, M
中科院分区：
文献类型：
--
作者：
Hock, R;Wilde, F;Bustin, M
染色体蛋白HMG-14/-17是核小体结合蛋白，其改变染色质纤维的结构并增强转录，但仅来自染色质模板。在这里，我们表明，在组织培养细胞中，HMG-17蛋白与活性转录位点共定位。用对应于HMG-14/-17的核小体结合结构域的肽孵育透化细胞特异性地阻止聚合酶II依赖性转录。在这些细胞中，肽从染色质中置换HMG-17并减少蛋白质的细胞含量。这些结果表明，染色质中HMG-14/-17的存在是有效的聚合酶II转录所必需的。在非透化的活跃转录细胞中，蛋白质以点状模式分散在整个细胞核中。在α-鹅膏毒肽或放线菌素D的转录抑制下，该蛋白逐渐重新分布，直到它与剪接因子SC 35一起完全定位于染色质间颗粒簇。结果表明，HMG-17与染色质的缔合是动态的而不是静态的，并且在没有转录的情况下，HMG-17从染色质释放并积聚在染色质间颗粒簇中。因此，作为染色质结构的结构元件的染色体蛋白质的核内分布可能是动态的，并且在功能上与细胞的转录活性相关。
Chromosomal proteins HMG-14/-17 are nucleosomal binding proteins, which alter the structure of the chromatin fiber and enhance transcription, but only from chromatin templates. Here we show that in tissue culture cells, HMG-17 protein colocalizes with sites of active transcription. Incubation of permeabilized cells with a peptide corresponding to the nucleosomal binding domains of HMG-14/-17 specifically arrested polymerase II-dependent transcription. In these cells the peptide displaces HMG-17 from chromatin and reduces the cellular content of the protein. These results suggest that the presence of HMG-14/-17 in chromatin is required for efficient polymerase II transcription. In non-permeabilized, actively transcribing cells, the protein is dispersed in a punctate pattern, throughout the nucleus. Upon transcriptional inhibition by a-amanitin or actinomycin D, the protein gradually redistributes until it localizes fully to interchromatin granule clusters, together with the splicing factor SC35, The results suggest that the association of HMG-17 with chromatin is dynamic rather than static, and that in the absence of transcription, HMG-17 is released from chromatin and accumulates in interchromatin granule clusters. Thus, the intranuclear distribution of chromosomal proteins which act as architectural elements of chromatin structure may be dynamic and functionally related to the transcriptional activity of the cell.