Transcription and Signal Transduction Lab, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, UK.
Transcription and Signal Transduction Lab, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, UK.
J Biol Chem. 2021 Jan-Jun;296:100214. doi: 10.1074/jbc.RA120.014616. Epub 2020 Dec 24.
The mitogen-responsive, ETS-domain transcription factor ELK-1 stimulates the expression of immediate early genes at the onset of the cell cycle and participates in early developmental programming. ELK-1 is subject to multiple levels of posttranslational control, including phosphorylation, SUMOylation, and ubiquitination. Recently, removal of monoubiquitin from the ELK-1 ETS domain by the Ubiquitin Specific Protease USP17 was shown to augment ELK-1 transcriptional activity and promote cell proliferation. Here we have used coimmunoprecipitation experiments, protein turnover and ubiquitination assays, RNA-interference and gene expression analyses to examine the possibility that USP17 acts antagonistically with the F-box protein FBXO25, an E3 ubiquitin ligase previously shown to promote ELK-1 ubiquitination and degradation. Our data confirm that FBXO25 and ELK-1 interact in HEK293T cells and that FBXO25 is active toward Hand1 and HAX1, two of its other candidate substrates. However, our data indicate that FBXO25 neither promotes ubiquitination of ELK-1 nor impacts on its transcriptional activity and suggest that an E3 ubiquitin ligase other than FBXO25 regulates ELK-1 ubiquitination and function.
丝裂原反应元件，ETS 结构域转录因子 Elk-1 在细胞周期开始时刺激即刻早期基因的表达，并参与早期发育编程。Elk-1 受到多种翻译后水平的控制，包括磷酸化、SUMO 化和泛素化。最近，泛素特异性蛋白酶 USP17 从 Elk-1 ETS 结构域中去除单泛素，增强了 Elk-1 的转录活性并促进细胞增殖。在这里，我们使用免疫共沉淀实验、蛋白周转和泛素化测定、RNA 干扰和基因表达分析来研究 USP17 是否可能与 F-box 蛋白 FBXO25 拮抗，FBXO25 是先前被证明能促进 Elk-1 泛素化和降解的 E3 泛素连接酶。我们的数据证实 FBXO25 和 Elk-1 在 HEK293T 细胞中相互作用，并且 FBXO25 对 Hand1 和 HAX1（其另外两个候选底物）具有活性。然而，我们的数据表明 FBXO25 既不促进 Elk-1 的泛素化，也不影响其转录活性，并表明除 FBXO25 之外的另一种 E3 泛素连接酶调节 Elk-1 的泛素化和功能。
