Intermittent hypoxia (IH), one of the major components of Obstructive Sleep Apnea Syndrome (OSAS), is at the origin of an oxidative stress responsible for deleterious cardiovascular alterations (1, 2). We have previously shown that the Hypoxia-Inducible Factor-1 (HIF-1) and one of its target genes, endothelin-1 (ET-1) a potent vasoactive peptide secreted by endothelial cells, were key players in these alterations. The role of reactive oxygen species in regulating HIF 1 activity is at least as important as hypoxia per se (3) and redox-signalling pathways have been linked to changes in zinc homeostasis. Indeed, redox signalling promotes zinc release from zinc-binding domains of proteins resulting in functional changes, a phenomenon called “zinc redox switch” (4). This discovery has led to the development of the unique concept that, in addition to serving a structural function in proteins, zinc ions were likely to play a dynamic signalling regulatory role. Therefore, the aim of this study was to observe whether perturbations of zinc homeostasis might modulate HIF-1 activity and ET-1 secretion, thereby leading to the cardiovascular alterations seen in OSA. This is supported by a recent study showing that severity of apneas and oxidative stress in OSA patients were associated with decreased zinc plasma levels (5).In this study we tested whether changes in intracellular zinc content could modulate ET-1 secretion by human microvascular endothelial cells (HMVECs) through redox-dependent HIF-1 activity. Moreover, we investigated the effects of zinc chelation by N,N,N’,N’-Tetrakis(2-pyridylmethyl)-ethylenediamine (TPEN) and ET-1 on endothelial cell migration using a wound-healing assay.Using TPEN, we have observed that a decrease in intracellular zinc concentration induced both ET-1 secretion and HMVEC motility (p<0.05 and p=0.056 respectively, versus control, two-way ANOVA with Bonferonni post-hoc comparisons, n=8 per group). We also demonstrated that TPEN activated the translocation of the HIF-1α subunit from the cytosol to the nucleus (p<0.01 versus control, t-test) where binding to the HIF-1β unit results in active HIF-1 and transcription of target genes. Finally, using siRNA directed against the HIF-1α subunit, we confirmed that HIF-1α was the mediator of the zinc-dependent ET-1 secretion and HMVEC migration. Indeed, the effects of TPEN and ET-1 were significantly reduced in HIF-1α neg cells compared to scrambled siRNA cells (p<0.001, two-way ANOVA with Bonferonni post-hoc comparisons, n=6 per group).These data uncover a novel regulatory role of zinc in HIF-1 activation by oxidative stress that could be particularly important in cardiovascular pathologies associated with OSA and other oxidative stress-related disorders.