Proteasomal inhibition attenuates transcriptional activity of hypoxia-inducible factor 1 (HIF-1) via specific effect on the HIF-1α C-terminal activation domain
Proteasomal inhibition attenuates transcriptional activity of hypoxia-inducible factor 1 (HIF-1) via specific effect on the HIF-1α C-terminal activation domain
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DOI：
10.1128/mcb.00552-06
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发表时间：
2006-08-01
影响因子：
5.3
通讯作者：
Stanbridge, Eric J.
中科院分区：
文献类型：
--
作者：
Kaluz, Stefan;Kaluzova, Milota;Stanbridge, Eric J.
泛素-蛋白酶体途径（UPP）参与多种细胞过程的调控。缺氧诱导因子1 α（HIF-1 α）是UPP的原型靶点，因此在蛋白酶体抑制条件下稳定。使用碳酸酐酶IX（CAIX）和血管内皮生长因子（VEGF）表达作为HIF-1活性的典型标志物，我们发现蛋白酶体抑制剂（PI）废除缺氧诱导的CAIX表达在所有测试的细胞系和VEGF表达在两个三。抑制作用的映射确定了HIF-1 α的C-末端激活结构域（CAD）作为PI的主要靶点。PI特异性抑制HIF-1 α CAD，尽管激活HIF-1 α辅激活因子p300和另一个p300富含半胱氨酸/组氨酸结构域1依赖性转录因子STAT-2。免疫共沉淀和谷胱甘肽S-转移酶唐斯表明，PI不破坏HIF-1 α和p300之间的相互作用。突变分析未能证实PI对HIF-1 α CAD功能调控中已知或推定的翻译后修饰位点的参与。我们的数据提供的证据，违反直觉的假设，抑制HIF-1功能可能是负责至少有一些抗肿瘤作用的蛋白酶体抑制。PI诱导的HIF-1 α衰减机制的进一步研究将为HIF-1活性的调节提供重要的、潜在的新见解，并可能确定HIF-1定向治疗的新靶点。
The ubiquitin-proteasome pathway (UPP) is involved in regulation of multiple cellular processes. Hypoxia-inducible factor 1 alpha (HIF-1 alpha) is a prototypic target of the UPP and, as such, is stabilized under conditions of proteasomal inhibition. Using carbonic anhydrase IX (CAIX) and vascular endothelial growth factor (VEGF) expression as paradigmatic markers of HIF-1 activity, we found that proteasomal inhibitors (PI) abrogated hypoxia-induced CAIX expression in all cell lines tested and VEGF expression in two out of three. Mapping of the inhibitory effect identified the C-terminal activation domain (CAD) of HIF-1 alpha as the primary target of PI. PI specifically inhibited the HIF-1 alpha CAD despite activating the HIF-1 alpha coactivator p300 and another p300 cysteine/histidine-rich domain 1-dependent transcription factor, STAT-2. Coimmunoprecipitation and glutathione S-transferase pull downs indicated that PI does not disrupt interactions between HIF-1 alpha and p300. Mutational analysis failed to confirm involvement of sites of known or putative posttranslational modifications in regulation of HIF-1 alpha CAD function by PI. Our data provide evidence for the counterintuitive hypothesis that inhibition of HIF-1 function could be responsible for at least some of the antitumor effects of proteasomal inhibition. Further studies of the mechanism of the PI-induced attenuation of HIF-1 alpha will provide important, potentially novel insight into regulation of HIF-1 activity and possibly identify new targets for HIF-directed therapy.