NCX1 Is a Novel Target Gene for Hypoxia-Inducible Factor-1 in Ischemic Brain Preconditioning
Background and Purpose—The sodium–calcium exchanger-1 (NCX1) represents a key mediator for maintaining [Na+]i and [Ca2+]i homeostasis. Although changes in NCX1 protein and transcript expression have been detected during stroke, its transcriptional regulation is still unknown. Thus far, however, there is evidence that hypoxia-inducible factor-1 (HIF-1) is a nuclear factor required for transcriptional activation of several genes implicated in stroke. The main objective of this study was to investigate whether NCX1 gene might be a novel target of HIF-1 in the brain.
Methods and Results—Here we report that: (1) in neuronal cells, NCX1 increased expression after oxygen and glucose deprivation or cobalt-induced HIF-1 activation was prevented by silencing HIF-1; (2) the brain NCX1 promoter cloned upstream of the firefly-luciferase gene contained 2 regions of HIF-1 target genes called hypoxia-responsive elements that are sensitive to oxygen and glucose deprivation or cobalt chloride; (3) HIF-1 specifically bound hypoxia-responsive elements on brain NCX1, as demonstrated by band-shift and chromatin immunoprecipitation assays; (4) HIF-1α silencing prevented NCX1 upregulation and neuroprotection induced by ischemic preconditioning; and (5) NCX1 silencing partially reverted the preconditioning-induced neuroprotection in rats.
Conclusions—NCX1 gene is a novel HIF-1 target, and HIF-1 exerts its prosurvival role through NCX1 upregulation during brain preconditioning.
- Received July 27, 2010.
- Accepted November 2, 2010.
- © 2011 American Heart Association, Inc.