Cytoglobin Up-regulated by Hydrogen Peroxide Plays a Protective Role in Oxidative Stress

Abstract

Cytoglobin (Cygb) is a recently discovered intracellular respiratory globin, which exists in all types of cells. It has been suggested that Cygb has a role in protecting cells against oxidative stress. In the present study we have tested this hypothesis. The N2a neuroblastoma cells were exposed to various kinds of insults, including hydrogen peroxide (H(2)O(2)), hypoxia, kainic acid, high extracellular CaCl(2), high osmolarity, UV irradiation and heat shock. Among them, only H(2)O(2)-treatment induced a significant up-regulation of cytoglobin mRNA level. We stably transfected N2a cells with Cygb-siRNA vectors and successfully knocked down Cygb. The Cygb-siRNA could exacerbate cell death upon H(2)O(2)-treatment, as demonstrated by MTT cell viability assay. Thus, Cygb in neuronal cells might be specifically induced under oxidative stress to protect them from death.

Cytoglobin, a Novel Member of the Globin Family, Protects Kidney Fibroblasts against Oxidative Stress under Ischemic Conditions

“…Recent studies of neuronal cancer cells support the finding of the antioxidative stress effects of Cygb. 10,11 In addition to Cygb, recent studies reported that hemoglobin 28 and myoglobin 45 also scavenge radicals, which emphasizes a role for globin proteins as antioxidants. Collectively, these in vitro studies suggest a novel antioxidative role for globins in addition to their known conventional facilitation of oxygen transport, and support the finding that Cygb serves as a defensive mechanism against oxidative stress.…”

Silencing neuroglobin enhances neuronal vulnerability to oxidative injury by down-regulating 14-3-3γ

“…In Ngb-transgenic mice, although infarct volume is reduced, long-term improvement in limb deficits after stroke does not occur [22] . We previously reported that Ngb gene expression is not altered in N2a cells following H 2 O 2 treatment [23] . These studies argue against the proposed protective role of Ngb.…”

“…Ngb-siRNA plasmid construction and identification Ngb siRNA expression vectors (named Ngb-siRNA) targeted to different regions of mouse Ngb cDNA (gi:18999491) were constructed using a GFP-expressing siRNA vector (p-Genesil-1, Wuhan Genesil Biotechnology, China), as previously reported [23] . The efficiency of Ngb-siRNA plasmids was confirmed by cotransfecting Ngb-siRNA and p-Ngb-EGFP plasmids [18] at a ratio of 4:1 into N2a cells using LipofectAMINE TM 2000 reagent (Invitrogen Life Technology, USA).…”

“…Stable N2a/Ngb-siRNA cell line N2a cells were cultured with Dulbecco's modified Eagle's medium (DMEM)/Opti-MEM (v/v=1:1)/5% (v/v) fetal bovine serum (FBS) (GIBCO BRL, Life Technologies, USA) in an incubator (Precision Scientific, USA) at 37 °C with 95% air/5% CO 2 (v/v) and 95% humidity, as reported previously [23] . N2a cells were transfected with Ngb-siRNA plasmids or control vectors, and stable cell lines were screened using a neomycin antibiotic (Sigma, USA) starting at a concentration of 800 µg/mL.…”

Microarray Analysis of Gene Expression by Rhei Rhizoma Water Extracts in a Hypoxia Model of Cultured Neurons

“…Cygb is ubiquitously expressed [3,20], and is upregulated in rat heart and liver following hypoxia [49] or in brain by hypoxia [10]. When Cygb mRNA was knocked down by siRNA, cell death was increased upon hydrogen peroxide-treatment [35], suggesting that Cygb protects cells against oxidative stress. In addition, Ngb expression was up-regulated following hypoxic challenges [54] and in ischemic-hypoxia brain injury [53].…”