v-Src-mediated down-regulation of SSeCKS metastasis suppressor gene promoter by the recruitment of HDAC1 into a USF1-Sp1-Sp3 complex
v-Src-mediated down-regulation of SSeCKS metastasis suppressor gene promoter by the recruitment of HDAC1 into a USF1-Sp1-Sp3 complex
复制标题
DOI：
10.1074/jbc.m702885200
复制
发表时间：
2007-09-14
影响因子：
4.8
通讯作者：
Gelman, Irwin H.
中科院分区：
文献类型：
--
作者：
Bu, Yahao;Gelman, Irwin H.
SSeCKS（（S）在bar下-rc（s）在bar下uppr（e）在bar下ssed（C）在bar下k）在bar下inase（s）在bar下substrate），也称为gravin/AKAP 12，是具有转移抑制活性的大支架蛋白。SSeCKS的两种主要同种型在两个独立的启动子（命名为α和β，相隔68 kb）的控制下在大多数细胞和组织类型中表达。SSeCKS转录和蛋白水平在Src和Ras转化的成纤维细胞和许多上皮肿瘤中严重降低。通过用渐进缺失分析剖析其启动子，我们鉴定了α近端启动子中-106和-49之间的序列作为最小的v-Src响应元件，其包含分别由USF 1和Sp1/Sp3结合的E盒和GC盒。E-盒和GC-盒对于v-Src响应性和基础启动子活性都是至关重要的。v-Src不改变USF 1在E盒的结合水平，但它增加了Sp1/Sp3与GC盒的结合，尽管它们的细胞蛋白丰度没有变化。V-Src/3 T3细胞中SSeCKS α和β转录水平可以通过用组蛋白脱乙酰酶抑制剂，阿司他丁A，但不能用DNA去甲基化剂，5-氮杂胞苷治疗来恢复。染色质的变化仅在α启动子上发现，即使β近端启动子包含类似的E盒和GC盒排列。HDAC 1的募集是必需的，足以引起α近端启动子活性的抑制，并且Sp1和/或Sp3的加入增强了抑制。我们的数据表明，β启动子的抑制是由Src诱导的α启动子染色质化的变化所促进的，该变化由USF 1-Sp1-Sp3复合物介导。
SSeCKS ( (S) under bar -rc (s) under bar uppr (e) under bar ssed (C) under bar (k) under bar inase (s) under bar ubstrate), also called gravin/AKAP12, is a large scaffolding protein with metastasis suppressor activity. Two major isoforms of SSeCKS are expressed in most cell and tissue types under the control of two independent promoters, designated alpha and beta, separated by 68 kb. SSeCKS transcript and protein levels are severely decreased in Src- and Ras-transformed fibroblasts and in many epithelial tumors. By dissecting its promoters with progressive deletion analysis, we identified the sequence between -106 and -49 in the alpha proximal promoter as the minimal v-Src-responsive element, which contains E- and GC-boxes bound by USF1 and Sp1/Sp3, respectively. Both E- and GC-boxes are crucial for v-Src-responsive and basal promoter activities. v-Src does not alter USF1 binding levels at the E- box, but it increases Sp1/Sp3 binding to the GC-box despite no change in their cellular protein abundance. SSeCKS alpha and beta transcript levels in v-Src/3T3 cells can be restored by treatment with the histone deacetylase inhibitor, trichostatin A, but not with the DNA demethylation agent, 5-azacytidine. Chromatin changes are found only on the alpha promoter even though the beta proximal promoter contains a similar E- and GC-box arrangement. Recruitment of HDAC1 is necessary and sufficient to cause repression of alpha proximal promoter activity, and the addition of Sp1 and/or Sp3 potentiates the repression. Our data suggest that suppression of the beta promoter is facilitated by Src- induced changes in the alpha promoter chromatinization mediated by a USF1-Sp1-Sp3 complex.