Nuclear Mobility and Activity of FOXA1 with Androgen Receptor Are Regulated by SUMOylation
Nuclear Mobility and Activity of FOXA1 with Androgen Receptor Are Regulated by SUMOylation
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DOI：
10.1210/me.2014-1035
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发表时间：
2014-10-01
影响因子：
--
通讯作者：
Palvimo, Jorma J.
中科院分区：
文献类型：
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作者：
Sutinen, Paivi;Rahkama, Vesa;Palvimo, Jorma J.
叉头盒（FOX）蛋白A1被称为先驱转录因子，因为它结合DNA中的靶位点，从而取代核小体以松开染色质并促进类固醇受体DNA结合附近。FOXA 1是前列腺发育的重要调节因子，与雄激素受体（AR）协同作用。到目前为止，对FOXA 1的翻译后修饰调控知之甚少。SUMO化，即小泛素样修饰蛋白（SUMO）对蛋白质的翻译后修饰，已成为转录调控中的一种重要调控机制。在这项工作中，我们通过COS-1细胞中的SUMO化测定表明，FOXA 1至少在其嵌入SUMO化共有区的三个赖氨酸中的两个中被修饰，K6和K389靠近其反式激活结构域，K267靠近其DNA结合结构域。我们还提供了SUMO-2/3修饰LNCaP前列腺癌细胞中内源性FOXA 1的证据。基于在HEK 293细胞中用mCherry融合的FOXA 1和EGFP融合的AR进行光漂白测定后的荧光恢复，FOXA 1的存在延缓激动剂结合的AR的核移动性。有趣的是，FOXA 1 SUMO化位点的突变减缓了先驱因子的移动性，进一步延缓了AR的核移动性。染色质免疫沉淀和基因表达分析表明，突变增强FOXA 1的染色质占有率以及其对AR调节的前列腺特异性抗原（PSA）基因座在LNCaP细胞中的活性。此外，该突变改变了FOXA 1影响LNCaP细胞增殖的能力。综上所述，这些结果强烈表明SUMO化可以调节FOXA 1与AR的转录活性。
Forkhead box (FOX) protein A1 has been dubbed a pioneer transcription factor because it binds target sites in DNA, thereby displacing nucleosomes to loosen chromatin and facilitating steroid receptor DNA binding nearby. FOXA1 is an important regulator of prostate development, collaborating with androgen receptor (AR). Post-translational modifications regulating FOXA1 are thus far poorly understood. SUMOylation, post-translational modification of proteins by small ubiquitin- like modifier (SUMO) proteins, has emerged as an important regulatory mechanism in transcriptional regulation. In this work, we show by SUMOylation assays in COS-1 cells that the FOXA1 is modified at least in two of its three lysines embedded in SUMOylation consensus, K6 and K389, in proximity to its transactivation domains and K267 proximal to its DNA-binding domain. We also provide evidence for SUMO-2/3 modification of endogenous FOXA1 in LNCaP prostate cancer cells. Based on fluorescence recovery after photobleaching assays with mCherry-fused FOXA1 and EGFP-fused AR in HEK293 cells, the presence of FOXA1 retards the nuclear mobility of agonist-bound AR. Interestingly, mutation of the FOXA1 SUMOylation sites slows down the mobility of the pioneer factor, further retarding the nuclear mobility of the AR. Chromatin immunoprecipitation and gene expression assays suggest that the mutation enhances FOXA1's chromatin occupancy as well as its activity on AR-regulated prostate-specific antigen (PSA) locus in LNCaP cells. Moreover, the mutation altered the ability of FOXA1 to influence proliferation of LNCaP cells. Taken together, these results strongly suggest that the SUMOylation can regulate the transcriptional activity of FOXA1 with the AR.