Sprouty2蛋白调节缺氧诱导因子-α(HIFα)蛋白水平及HIFα反应性基因的转录。
Sprouty2 Protein Regulates Hypoxia-inducible Factor-α (HIFα) Protein Levels and Transcription of HIFα-responsive Genes.
作者信息
Hicks Kristin C, Patel Tarun B
机构信息
From the Department of Molecular Pharmacology and Therapeutics, Loyola University Chicago, Maywood, Illinois 60153, and.
the Albany College of Pharmacy and Health Sciences, Albany, New York 12208
出版信息
J Biol Chem. 2016 Aug 5;291(32):16787-801. doi: 10.1074/jbc.M116.714139. Epub 2016 Jun 8.
The α-subunits of hypoxia-inducible factors (HIF1α and HIF2α) promote transcription of genes that regulate glycolysis and cell survival and growth. Sprouty2 (Spry2) is a modulator of receptor tyrosine kinase signaling and inhibits cell proliferation by a number of different mechanisms. Because of the seemingly opposite actions of HIFα subunits and Spry2 on cellular processes, we investigated whether Spry2 regulates the levels of HIF1α and HIF2α proteins. In cell lines from different types of tumors in which the decreased protein levels of Spry2 have been associated with poor prognosis, silencing of Spry2 elevated HIF1α protein levels. Increases in HIF1α and HIF2α protein levels due to silencing of Spry2 also up-regulated HIFα target genes. Using HIF1α as a prototype, we show that Spry2 decreases HIF1α stability and enhances the ubiquitylation of HIF1α by a von Hippel-Lindau protein (pVHL)-dependent mechanism. Spry2 also exists in a complex with HIF1α. Because Spry2 can also associate with pVHL, using a mutant form of Spry2 (3P/3A-Spry2) that binds HIF1α, but not pVHL, we show that WT-Spry2, but not the 3P/3A-Spry2 decreases HIF1α protein levels. In accordance, expression of WT-Spry2, but not 3P/3A-Spry2 results in a decrease in HIF1α-sensitive glucose uptake. Together our data suggest that Spry2 acts as a scaffold to bring more pVHL/associated E3 ligase in proximity of HIF1α and increase its ubiquitylation and degradation. This represents a novel action for Spry2 in modulating biological processes regulated by HIFα subunits.
缺氧诱导因子的α亚基(HIF1α和HIF2α)可促进调控糖酵解以及细胞存活与生长的基因转录。Sprouty2(Spry2)是受体酪氨酸激酶信号传导的调节剂,通过多种不同机制抑制细胞增殖。由于HIFα亚基和Spry2在细胞过程中似乎具有相反的作用,我们研究了Spry2是否调节HIF1α和HIF2α蛋白的水平。在不同类型肿瘤的细胞系中,Spry2蛋白水平降低与预后不良相关,沉默Spry2可提高HIF1α蛋白水平。由于Spry2沉默导致的HIF1α和HIF2α蛋白水平升高也上调了HIFα靶基因。以HIF1α为原型,我们发现Spry2降低HIF1α的稳定性,并通过一种依赖于冯·希佩尔-林道蛋白(pVHL)的机制增强HIF1α的泛素化。Spry2也与HIF1α存在于一个复合物中。由于Spry2也可与pVHL结合,我们使用一种结合HIF1α但不结合pVHL的Spry2突变形式(3P/3A-Spry2),发现野生型Spry2(WT-Spry2)而非3P/3A-Spry2可降低HIF1α蛋白水平。相应地,WT-Spry2而非3P/3A-Spry2的表达导致HIF1α敏感的葡萄糖摄取减少。我们的数据共同表明,Spry2作为一种支架,使更多的pVHL/相关E3连接酶靠近HIF1α,并增加其泛素化和降解。这代表了Spry2在调节由HIFα亚基调控的生物学过程中的一种新作用。
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