Heme oxygenase-2 knockout neurons are less vulnerable to hemoglobin toxicity

Bret Rogers, Vladimir Yakopson, Zhi Ping Teng, Yaping Guo, Raymond F. Regan

Research output: Contribution to journalArticle

75 Citations (Scopus)

Abstract

When cortical neurons are exposed to hemoglobin, they undergo oxidative stress that ultimately results in iron-dependent cell death. Heme oxygenase (HO)-2 is constitutively expressed in neurons and catalyzes heme breakdown. Its role in the cellular response to hemoglobin is unclear. We tested the hypothesis that HO-2 attenuates hemoglobin neurotoxicity by comparing reactive oxygen species (ROS) formation and cell death in wild-type and HO-2 knockout cortical cultures. Consistent with prior observations, hemoglobin increased ROS generation, detected by fluorescence intensity after dihydrorhodamine 123 or dichlorofluorescin-diacetate loading, in wild-type neurons. This fluorescence was significantly attenuated in cultures prepared from HO-2 knockout mice, and cell death as determined by propidium iodide staining was decreased. In other experiments, hemoglobin exposure was continued for 19 h; cell death as quantified by LDH release was decreased in knockout cultures, and was further diminished by treatment with the HO inhibitor tin protoporphyrin IX. In contrast, HO-2 knockout neurons were more vulnerable than wild-type neurons to inorganic iron. HO-1, ferritin, and superoxide dismutase expression in HO-2 -/- cultures did not differ significantly from that observed in HO-2 +/+ cultures; cellular glutathione levels were slightly higher in knockout cultures. These results suggest that heme breakdown by heme oxygenase accelerates the oxidative neurotoxicity of hemoglobin, and may contribute to neuronal injury after CNS hemorrhage.

Original languageEnglish (US)
Pages (from-to)872-881
Number of pages10
JournalFree Radical Biology and Medicine
Volume35
Issue number8
DOIs
StatePublished - Oct 15 2003
Externally publishedYes

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Neurons
Toxicity
Hemoglobins
Cell death
Cell Death
Heme Oxygenase (Decyclizing)
Heme
Reactive Oxygen Species
Iron
Fluorescence
Heme Oxygenase-1
Oxidative stress
Propidium
Ferritins
heme oxygenase-2
Cell culture
Knockout Mice
Superoxide Dismutase
Glutathione
Oxidative Stress

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Physiology (medical)

Cite this

Heme oxygenase-2 knockout neurons are less vulnerable to hemoglobin toxicity. / Rogers, Bret; Yakopson, Vladimir; Teng, Zhi Ping; Guo, Yaping; Regan, Raymond F.

In: Free Radical Biology and Medicine, Vol. 35, No. 8, 15.10.2003, p. 872-881.

Research output: Contribution to journalArticle

Rogers, Bret ; Yakopson, Vladimir ; Teng, Zhi Ping ; Guo, Yaping ; Regan, Raymond F. / Heme oxygenase-2 knockout neurons are less vulnerable to hemoglobin toxicity. In: Free Radical Biology and Medicine. 2003 ; Vol. 35, No. 8. pp. 872-881.
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