Neurons lacking iron regulatory protein-2 are highly resistant to the toxicity of hemoglobin.
The effect of iron regulatory protein-2 (IRP2) on ferritin expression and neuronal vulnerability to hemoglobin was assessed in primary cortical cell cultures prepared from wild-type and IRP2 knockout mice. Baseline levels of H and L-ferritin subunits were significantly increased in IRP2 knockout neurons and astrocytes. Hemoglobin was toxic to wild-type neurons in mixed neuron-astrocyte cultures, with an LC(50) near 3 microM for a 24 h exposure. Neuronal death was reduced by 85-95% in knockout cultures, and also in cultures containing knockout neurons plated on wild-type astrocytes. Protein carbonylation, reactive oxygen species formation, and heme oxygenase-1 expression after hemoglobin treatment were also attenuated by IRP2 gene deletion. These results suggest that IRP2 binding activity increases the vulnerability of neurons to hemoglobin, possibly by reducing ferritin expression. Therapeutic strategies that target this regulatory mechanism may be beneficial after hemorrhagic CNS injuries.
Department of Emergency Medicine, Thomas Jefferson University, 1020 Sansom Street, Thompson Building Room 239, Philadelphia, PA 19107, USA. Raymond.Regan@jefferson.edu
Raymond F
RF
Regan
Mai
M
Chen
Zhi
Z
Li
Xuefeng
X
Zhang
Luna
L
Benvenisti-Zarom
Jing
J
Chen-Roetling
D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000235:genetics; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000378:metabolism* / Q000503:physiopathology; D002543:Cerebral Hemorrhage / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D004351:Drug Resistance / Q000235:genetics*; D005260:Female; D005293:Ferritins / Q000378:metabolism; D020022:Genetic Predisposition to Disease / Q000235:genetics; D051547:Heme Oxygenase-1 / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism / Q000633:toxicity*; D019189:Iron Metabolism Disorders / Q000235:genetics / Q000378:metabolism*; D035942:Iron Regulatory Protein 2 / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009410:Nerve Degeneration / Q000139:chemically induced / Q000235:genetics / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D018384:Oxidative Stress / Q000235:genetics; D011485:Protein Binding / Q000235:genetics
D006454:Hemoglobins; D005293:Ferritins; D051547:Heme Oxygenase-1; D035942:Iron Regulatory Protein 2