Copper Is Required for Cobalt-Induced Transcriptional Activity of Hypoxia-Inducible Factor-1

Abstract

Cobalt inhibits prolyl hydroxylases, leading to the accumulation of hypoxia-inducible factor-1␣ (HIF-1␣) and a concomitant increase in the transcriptional activity of HIF-1. Therefore, cobalt has been under development as a drug for activating HIF-1 under some disease conditions. However, it has been shown that ischemic conditions resulted in the loss of copper, and the activation of HIF-1 would not occur unless copper was supplemented. The present study was undertaken to test the hypothesis that copper is also required for the cobalt activation of HIF-1 transcriptional activity. Human umbilical vein endothelial cells subjected to treatment with cobalt chloride (CoCl 2 ) at concentrations above 25 M for 2 h resulted in an accumulation of HIF-1␣, which was determined by Western blot analysis, and an increase in the expression of vascular endothelial growth factor (VEGF), which was determined by real-time reverse transcription-polymerase chain reaction analysis for mRNA levels and enzyme-linked immunosorbent assay analysis for protein levels. The copper chelator tetraethylenepentamine at 25 M did not significantly affect the accumulation of HIF-1␣ but blocked increases in VEGF mRNA and protein levels, an effect that could be reversed by the addition of 25 M copper sulfate (CuSO 4 ). In addition, gene silencing of the copper chaperone for Cu,Zn-superoxide dismutase blocked VEGF expression with little effect on cobalt-induced HIF-1␣ accumulation. The present study thus demonstrates that copper was required for cobalt-activated transcriptional activity of HIF-1, although copper did not affect cobalt-induced accumulation of HIF-1␣ in the cells.

Behind the Link between Copper and Angiogenesis: Established Mechanisms and an Overview on the Role of Vascular Copper Transport Systems

“…1) [23]. A recent study on HUVEC cultures further confirmed that copper does not significantly affect endothelial HIF-1α accumulation, but the related transcriptional activity is impaired when intracellular metal availability/trafficking is depressed [26]. This concept is sustained by a bulk of literature showing that ischaemic heart tissue suffers from poor copper content, despite abundant HIF-1α levels [27].…”

The Inorganic Perspective of VEGF: Interactions of Cu2+ with Peptides Encompassing a Recognition Domain of the VEGF Receptor

“…A number of studies have investigated the stimulatory action of copper on VEGF production and tumor angiogenesis [36,41,59] as well as the repressive effects exerted by copper-chelating on HIF-1α mediated expression of VEGF [60,61].…”

Angiogenesis and Cardiac Hypertrophy

“…85 According to recent studies, cobalt-induced stabilization of Hif-1α is dependent on copper. 86,87 Furthermore, copper supplementation reversed contractile dysfunction and prevented transition to heart failure in pressure-overloaded mice, at least in part through promotion of myocardial angiogenesis. 88 In addition to cobalt and copper function, several approved drugs have been reported to affect myocardial angiogenesis.…”