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J Cereb Blood Flow Metab. 2012 Jun;32(6):1046-60. doi: 10.1038/jcbfm.2012.21. Epub 2012 Apr 4.

Neuroglobin regulates hypoxic response of neuronal cells through Hif-1α- and Nrf2-mediated mechanism.

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1
High Altitude Physiology Laboratory, Defence Institute of High Altitude Research, Jammu and Kashmir, India.

Abstract

Oxygen sensing in hypoxic neurons has been classically attributed to cytochrome c oxidase and prolyl-4-hydroxylases and involves stabilization of transcription factors, hypoxia-inducible factor-1α (Hif-1α) and nuclear factor erythroid 2-related factor 2 (Nrf2) that mediate survival responses. On the contrary, release of cytochrome c into the cytosol during hypoxic stress triggers apoptosis in neuronal cells. We, here advocate that the redox state of neuroglobin (Ngb) could regulate both Hif-1α and Nrf2 stabilization and cytochrome c release during hypoxia. The hippocampal regions showing higher expression of Ngb were less susceptible to global hypoxia-mediated neurodegeneration. During normoxia, Ngb maintained cytochrome c in the reduced state and prevented its release from mitochondria by using cellular antioxidants. Greater turnover of oxidized cytochrome c and increased utilization of cellular antioxidants during acute hypoxia altered cellular redox status and stabilized Hif-1α and Nrf2 through Ngb-mediated mechanism. Chronic hypoxia, however, resulted in oxidation and degradation of Ngb, accumulation of ferric ions and release of cytochrome c that triggered apoptosis. Administration of N-acetyl-cysteine during hypoxic conditions improved neuronal survival by preventing Ngb oxidation and degradation. Taken together, these results establish a role for Ngb in regulating both the survival and apoptotic mechanisms associated with hypoxia.

PMID:
22472608
PMCID:
PMC3367222
DOI:
10.1038/jcbfm.2012.21
[Indexed for MEDLINE]
Free PMC Article
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