SUMO-mediated inhibition of glucocorticoid receptor synergistic activity depends on stable assembly at the promoter but not on DAXX
SUMO-mediated inhibition of glucocorticoid receptor synergistic activity depends on stable assembly at the promoter but not on DAXX
复制标题
DOI：
10.1210/me.2007-0581
复制
发表时间：
2008-09-01
影响因子：
--
通讯作者：
Iniguez-Lluhi, Jorge A.
中科院分区：
文献类型：
--
作者：
Holmstrom, Sam R.;Chupreta, Sergey;Iniguez-Lluhi, Jorge A.
多种转录因子，包括核受体家族的成员，具有一个或多个拷贝的短调控基序，其以上下文依赖的方式限制协同反式激活。这些协同控制（SC）基序发挥其作用，作为网站的翻译后修饰的小泛素样修饰（SUMO）蛋白。通过分析糖皮质激素受体（GR）的协同控制和SUMO化的要求，我们发现一个完整的配体结合结构域和一个参与的DNA结合结构域二聚化界面对于有效的协同控制是必要的。然而，这些促进GR-DNA复合物稳定组装的特征是SUMO化下游所需的，因为它们的破坏或缺失不干扰SUMO修饰。值得注意的是，在缺乏这些特征的情况下，对SUMO化作用的敏感性可以简单地通过异源DNA结合结构域稳定DNA相互作用来恢复。这些数据表明，与DNA的稳定相互作用是SUMO依赖性转录抑制的重要先决条件。GR占据的基因组区域的分析表明，SC基序SUMO化的影响是最明显的多个，接近理想的GR结合位点，SUMO化选择性地影响诱导的内源性基因。虽然SUMO结合蛋白DAXX已被提议介导GR SUMO化的抑制作用，但我们发现DAXX的抑制作用不依赖于GR SUMO化。此外，无论是表达，也不敲低DAXX影响相扑效应GR。因此，我们建议，GR的DNA上的多个位点的稳定结合允许相扑依赖的招聘DAXX不同的抑制因子。
Multiple transcription factors, including members of the nuclear receptor family, harbor one or more copies of a short regulatory motif that limits synergistic transactivation in a context-dependent manner. These synergy control (SC) motifs exert their effects by serving as sites for posttranslational modification by small ubiquitin-like modifier ( SUMO) proteins. By analyzing the requirements for both synergy control and SUMOylation in the glucocorticoid receptor (GR), we find that an intact ligand-binding domain and an engaged DNA-binding domain dimerization interface are necessary for effective synergy control. However, these features, which promote stable assembly of GR-DNA complexes, are required downstream of SUMOylation because their disruption or deletion does not interfere with SUMO modification. Remarkably, in the absence of these features, sensitivity to the effects of SUMOylation can be restored simply by stabilization of DNA interactions through a heterologous DNA binding domain. The data indicate that stable interaction with DNA is an important prerequisite for SUMO-dependent transcriptional inhibition. Analysis of genomic regions occupied by GR indicates that the effects of SC motif SUMOylation are most evident at multiple, near-ideal GR binding sites and that SUMOylation selectively affects the induction of linked endogenous genes. Although the SUMO-binding protein DAXX has been proposed to mediate the inhibitory effects of GR SUMOylation, we find that inhibition by DAXX is independent of GR SUMOylation. Furthermore, neither expression nor knockdown of DAXX influences SUMO effects on GR. We therefore propose that stable binding of GR to multiple sites on DNA allows for the SUMO-dependent recruitment of inhibitory factors distinct from DAXX.