Nitric oxide reverses desferrioxamine- and hypoxia-evoked HIF-1α accumulation-implications for prolyl hydroxylase activity and iron
Nitric oxide reverses desferrioxamine- and hypoxia-evoked HIF-1α accumulation-implications for prolyl hydroxylase activity and iron
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DOI：
10.1016/j.yexcr.2005.02.018
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发表时间：
2005-05-15
影响因子：
3.7
通讯作者：
Brüne, B
中科院分区：
文献类型：
--
作者：
Callapina, M;Zhou, J;Brüne, B
缺氧诱导因子1（HIF-1）感知并协调细胞对缺氧的反应。HIF-1活性主要由其α亚基的稳定性调节决定，所述α亚基在常氧下由于脯氨酰羟化酶（PHD）的羟基化而被26 S蛋白酶体降解，但在缺氧下稳定。除了缺氧，一氧化氮（NO）稳定HIF-1 α，并促进低氧反应靶基因的表达在常氧下。然而，在缺氧时，NO减弱HIF-1 α的稳定和基因激活。我们的目的是解释缺氧条件下NO的对比行为。我们使用铁螯合剂去铁胺（DFX）或缺氧在HEK 293细胞中积累HIFI α。一旦蛋白质积累，我们提供NO供体并跟踪HIF-1 α的消失。NO诱导的HIF 1 α不稳定被蛋白酶体抑制或阻断PHD活性逆转。通过使用von Hippel Lindau（pVHL）-HIF-1 α捕获测定，我们继续证明了在DFX/NO下pVHL与HIF-1 α的结合，而不是单独的DFX。与单独缺氧相比，缺氧/NO条件下细胞内游离铁增加，我们假设游离铁增加有助于恢复PHD活性。允许有效的PHD激活的变量，如氧可用性，铁含量，或辅因子的可及性，在该端允许NO调节HIF-1 α的积累。(c)2005年Etsevier Inc. All rights reserved.
Hypoxia inducible factor 1 (HIF-1) senses and coordinates cellular responses towards hypoxia. HIF-1 activity is primarily determined by stability regulation of its alpha subunit that is degraded by the 26S proteasome under normoxia due to hydroxylation by prolyl hydroxylases (PHDs) but is stabilized under hypoxia. Besides hypoxia, nitric oxide (NO) stabilizes HIF-1 alpha and promotes hypoxia-responsive target gene expression under normoxia. However, in hypoxia, NO attenuates HIF-lalpha stabilization and gene activation. It was our intention to explain the contrasting behavior of NO under hypoxia. We used the iron chelator desferrioxamine (DFX) or hypoxia to accumulate HIFI alpha in HEK293 cells. Once the protein accumulated, we supplied NO donors and followed HIF-1 alpha disappearance. NO-evoked HIF1 alpha destabilization was reversed by proteasomal inhibition or by blocking PHD activity. By using the von Hippel Lindau (pVHL)-HIFI alpha capture assay, we went on to demonstrate binding of pVHL to HIF-1 alpha under DFX/NO but not DFX alone. Showing increased intracellular free iron under conditions of hypoxia/NO compared to hypoxia alone, we assume that increased free iron contributes to regain PHD activity. Variables that allow efficient PHD activation such as oxygen availability, iron content, or cofactor accessibility at that end allow NO to modulate HIF-lalpha accumulation. (c) 2005 Etsevier Inc. All rights reserved.