Iron Regulatory Protein 1 Suppresses Hypoxia-Induced Iron Uptake Proteins Expression and Decreases Iron Levels in HepG2 Cells
Iron Regulatory Protein 1 Suppresses Hypoxia-Induced Iron Uptake Proteins Expression and Decreases Iron Levels in HepG2 Cells
复制标题
铁调节蛋白 1 抑制缺氧诱导的铁摄取蛋白表达并降低 HepG2 细胞中的铁水平
DOI：
10.1002/jcb.25147
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发表时间：
2015-09-01
影响因子：
4
通讯作者：
Zhu, Li
中科院分区：
文献类型：
--
作者：
Cheng, Chun-Ming;Wang, Dan;Zhu, Li
转铁蛋白受体(TfR1)和二价金属转运蛋白1(DMT1)是细胞铁摄取的重要蛋白质，在低氧条件下，两者都通过低氧诱导因子1(HIF-1)与低氧反应元件(HRE)的结合而在转录水平上进行调控。这些蛋白还通过铁调节蛋白1(Irp1)与位于mRNA非翻译区(UTR)的铁反应元件(IRES)结合在转录后进行调节，以控制细胞铁的稳态。在缺铁细胞中，Irp1-ire相互作用稳定TfR1和DMT1mRNAs，增强铁摄取。然而，对于Irp1在低氧条件下对细胞铁稳态调节的影响，人们知之甚少。因此，为了研究Irp1在低氧条件下的作用，我们利用HepG2细胞进行了过表达和基因敲除实验。Irp1的过表达抑制了低氧诱导的TfR1和DMT1(+ire)的表达增加，降低了TfR1和DMT1(+ire)mRNAs在低氧下的稳定性，而Irp1的过表达则进一步增加了低氧诱导的这两种蛋白的表达，阻止了低氧诱导的IRE依赖的荧光素酶活性的下降。在低氧条件下，当Irp1过表达时，细胞亚铁摄取、不稳定铁池(LIP)和细胞内总铁减少，而当Irp1被击倒时，细胞内总铁进一步增加。随着缺氧时间的延长，Irp1表达下降，TfR1/DMT1(+ire)表达增加，但Irp1与TfR1/DMT1 mRNA的IRE结合保持不变。综上所述，Irp1抑制了TfR1/DMT1(+ire)的表达，限制了细胞铁含量，减少了乳酸脱氢酶(LDH)的释放。J.细胞。生物化学。116：1919-1931,2015。(C)2015年威利期刊公司。
Transferrin receptor (TfR1) and divalent metal transporter 1 (DMT1) are important proteins for cellular iron uptake, and both are regulated transcriptionally through the binding of hypoxia-inducible factor 1 (HIF-1) to hypoxia-responsive elements (HREs) under hypoxic conditions. These proteins are also regulated post-transcriptionally through the binding of iron regulatory protein 1 (IRP1) to iron-responsive elements (IREs) located in the mRNA untranslated region (UTR) to control cellular iron homeostasis. In iron-deficient cells, IRP1-IRE interactions stabilize TfR1 and DMT1 mRNAs, enhancing iron uptake. However, little is known about the impact of IRP1 on the regulation of cellular iron homeostasis under hypoxia. Thus, to investigate the role of IRP1 in hypoxic condition, overexpression and knockdown assays were performed using HepG2 cells. The overexpression of IRP1 suppressed the hypoxia-induced increase in TfR1 and DMT1 (+IRE) expression and reduced the stability of TfR1 and DMT1 (+IRE) mRNAs under hypoxia, whereas IRP1 knockdown further increased the hypoxia-induced expression of both proteins, preventing the decrease in IRE-dependent luciferase activity induced by hypoxia. Under hypoxic conditions, ferrous iron uptake, the labile iron pool (LIP), and total intracellular iron reduced when IRP1 was overexpressed and further increased when IRP1 was knocked down. IRP1 expression declined and TfR1/DMT1 (+IRE) expression increased with the time of hypoxia prolonged, whereas the binding of IRP1 to the IRE of TfR1/DMT1 mRNA maintained. In summary, IRP1 suppressed TfR1/DMT1 (+IRE) expression, limited the cellular iron content and decreased lactate dehydrogenase (LDH) release induced by hypoxia. J. Cell. Biochem. 116: 1919-1931, 2015. (c) 2015 Wiley Periodicals, Inc.