Differentiating the functional role of hypoxia-inducible factor (HIF)-1α and HIF-2α (EPAS-1) by the use of RNA interference: erythropoietin is a HIF-2α target gene in Hep3B and Kelly cells

来自 EBSCO

阅读量：

作者：

C Warnecke，Z Zaborowska，J Kurreck，VA Erdmann，U Frei，M Wiesener，Kai‐Uwe Eckardt

展开

摘要：

Activation of the hypoxia-inducible factor alpha-subunits, HIF-1alpha and HIF-2alpha, seems to be subject to similar regulatory mechanisms, and transgene approaches suggested partial functional redundancy. Here, we used RNA interference to determine the contribution of HIF-1alpha vs. HIF-2alpha to the hypoxic gene induction. Surprisingly, most genes tested were responsive only to the HIF-1alpha siRNA, showing no effect by HIF-2alpha knock-down. The same was found for the activation of reporter genes driven by hypoxia-responsive elements (HREs) from the erythropoietin (EPO), vascular endothelial growth factor, or phosphoglycerate kinase gene. Interestingly, EPO was the only gene investigated that showed responsiveness only to HIF-2alpha knock-down, as observed in Hep3B and Kelly cells. In contrast to the EPO-HRE reporter, the complete EPO enhancer displayed dependency on HIF-2alpha regulation, indicating that additional cis-acting elements confer HIF-2alpha specificity within this region. In 786-0 cells lacking HIF-1alpha protein, the identified HIF-1alpha target genes were regulated by HIF-2alpha. Overexpression of the HIFalpha subunits in different cell lines also led to a loss of target gene specificity. In conclusion, we found a remarkably restricted target gene specificity of the HIFalpha subunits, which can be overcome in cells with perturbations in the pVHL/HIF system and under forced expression.

展开

关键词：

hypoxia‐responsive element EPO HLF

DOI：

10.1096/fj.04-1640fje

被引量：

758

年份：

2004