Decreased Recognition of SUMO-Sensitive Target Genes following Modification of SF-1 (NR5A1)
Decreased Recognition of SUMO-Sensitive Target Genes following Modification of SF-1 (NR5A1)
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DOI：
10.1128/mcb.00103-08
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发表时间：
2008-12-15
影响因子：
5.3
通讯作者：
Ingraham, Holly A.
中科院分区：
文献类型：
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作者：
Campbell, Lioudmila A.;Faivre, Emily J.;Ingraham, Holly A.
SUMO修饰的核受体，包括组成型活性受体类固醇生成因子1（SF-1; NR 5A 1），提出抑制其转录活性。我们研究了SF-1类小泛素化在两个保守的赖氨酸（Lys 119和Lys 194）的功能和结构的后果，这两个赖氨酸分别位于DNA结合结构域（DBD）和配体结合结构域（LBD）附近。令人惊讶的是，虽然先前的功能丧失研究预测，在Lys 194的类小泛素化将极大地影响SF-1的功能，完全类小泛素化的SF-1 LBD蛋白的构象和辅调节剂的招聘是不变的或适度受损。在Lys 194处的类小泛素化也适度地减少Ser 203磷酸化。与这些研究结果相反，在赖氨酸119的DBD的sumoylation导致了显着的和选择性的损失的DNA结合到非典型的SF-1的目标，如α，这种结合缺陷扩展到所有网站时，sumoylated人类突变体（R92 Q）蛋白，表现出较低的活性，被使用。与该结果一致，与野生型SF-1相比，K119 R突变体被选择性地募集到内源性FATABIN α启动子中的“SUMO敏感”位点，导致转录增加。DNA结合和Lys 119的类小泛素化似乎是相互排斥的，这表明一旦SF-1与DNA结合，类小泛素化在调节SF-1活性方面可能不那么重要。我们认为，细胞核受体的类小泛素化对细胞的活性产生了影响。
SUMO modification of nuclear receptors, including the constitutively active receptor steroidogenic factor 1 (SF-1; NR5A1), is proposed to repress their transcriptional activity. We examined the functional and structural consequences of SF-1 sumoylation at two conserved lysines (Lys119 and Lys194) that reside adjacent to the DNA-binding domain (DBD) and ligand-binding domain (LBD), respectively. Surprisingly, while previous loss-of-function studies predicted that sumoylation at Lys194 would greatly impact SF-1 function, the conformation and coregulator recruitment of fully sumoylated SF-1 LBD protein was either unchanged or modestly impaired. Sumoylation at Lys194 also modestly reduced Ser203 phosphorylation. In contrast to these findings, sumoylation of the DBD at Lys119 resulted in a marked and selective loss of DNA binding to noncanonical SF-1 targets, such as inhibin alpha; this binding deficit was extended to all sites when the sumoylated human mutant (R92Q) protein, which exhibits lower activity, was used. Consistent with this result, the K119R mutant, compared to wild-type SF-1, was selectively recruited to a "SUMO-sensitive" site in the endogenous inhibin alpha promoter, leading to increased transcription. DNA binding and sumoylation of Lys119 appeared to be mutually exclusive, suggesting that once SF-1 is bound to DNA, sumoylation may be less important in regulating SF-1 activity. We propose that sumoylation of nuclear receptors imposes an active