Binding of HMG-I(Y) imparts architectural specificity to a positioned nucleosome on the promoter of the human interleukin-2 receptor alpha gene.
Binding of HMG-I(Y) imparts architectural specificity to a positioned nucleosome on the promoter of the human interleukin-2 receptor alpha gene.
复制标题
HMG-1(Y)的结合赋予人白细胞介素2受体α基因启动子上定位的核小体结构特异性。
DOI：
10.1128/mcb.20.13.4666-4679.2000
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发表时间：
2000
影响因子：
5.3
通讯作者：
Nissen,MS
中科院分区：
文献类型：
--
作者：
Reeves,R;Leonard,WJ;Nissen,MS
白细胞介素-2受体α链（IL-2 R α）基因的转录诱导是调节哺乳动物T细胞介导的免疫的关键事件。在体内，T细胞限制性蛋白Elf-1和一般结构转录因子HMG-I（Y）通过结合人IL-2 R α基因近端启动子中的特异性正调控区（PRRII），在人IL-2 R α基因的转录调控中协同作用。采用染色质重建分析，我们证明了PRRII元件中的HMG-I（Y）和Elf-1的结合位点在体外被掺入到强定位的核小体中。各种分析技术被用来确定一个稳定的核心颗粒被定位在大多数的PRRII元件，并且该核小体仅表现出有限量的横向平移移动性。无论其翻译设置如何，核小体的体外位置使得HMG-I（Y）和Elf-1的DNA识别序列都位于核心颗粒的表面上。限制性核酸酶可及性分析表明，当IL-2 R α基因沉默时，未刺激淋巴细胞中的PRRII元件上也存在类似位置的核小体，并表明该核心颗粒在体内基因转录激活后重塑。采用共价连接到其C-末端的化学裂解试剂1，10-菲咯啉铜（II）的体外实验证明，HMG-I（Y）蛋白以方向特异性方式结合到定位的PRRII核小体，从而赋予核心颗粒独特的结构构型。总之，这些发现表明HMG-I（Y）蛋白在体内淋巴细胞IL-2 R α转录激活过程中协助PRRII启动子元件上关键位置核小体重塑的作用。
Transcriptional induction of the interleukin-2 receptor alpha-chain (IL-2Rα) gene is a key event regulating T-cell-mediated immunity in mammals. In vivo, the T-cell-restricted protein Elf-1 and the general architectural transcription factor HMG-I (Y) cooperate in transcriptional regulation of the human IL-2Rα gene by binding to a specific positive regulatory region (PRRII) in its proximal promoter. Employing chromatin reconstitution analyses, we demonstrate that the binding sites for both HMG-I (Y) and Elf-1 in the PRRII element are incorporated into a strongly positioned nucleosome in vitro. A variety of analytical techniques was used to determine that a stable core particle is positioned over most of the PRRII element and that this nucleosome exhibits only a limited amount of lateral translational mobility. Regardless of its translational setting, the in vitro position of the nucleosome is such that DNA recognition sequences for both HMG-I (Y) and Elf-1 are located on the surface of the core particle. Restriction nuclease accessibility analyses indicate that a similarly positioned nucleosome also exists on the PRRII element in unstimulated lymphocytes when the IL-2Rα gene is silent and suggest that this core particle is remodeled following transcriptional activation of the gene in vivo. In vitro experiments employing the chemical cleavage reagent 1, 10-phenanthroline copper (II) covalently attached to its C-terminal end demonstrate that HMG-I (Y) protein binds to the positioned PRRII nucleosome in a direction-specific manner, thus imparting a distinct architectural configuration to the core particle. Together, these findings suggest a role for the HMG-I (Y) protein in assisting the remodeling of a critically positioned nucleosome on the PRRII promoter element during IL-2Rα transcriptional activation in lymphocytes in vivo.