Over-expression of heme oxygenase-1 promotes oxidative mitochondrial damage in rat astroglia.
Glial heme oxygenase-1 is over-expressed in the CNS of subjects with Alzheimer disease (AD), Parkinson disease (PD) and multiple sclerosis (MS). Up-regulation of HO-1 in rat astroglia has been shown to facilitate iron sequestration by the mitochondrial compartment. To determine whether HO-1 induction promotes mitochondrial oxidative stress, assays for 8-epiPGF(2alpha) (ELISA), protein carbonyls (ELISA) and 8-OHdG (HPLC-EC) were used to quantify oxidative damage to lipids, proteins, and nucleic acids, respectively, in mitochondrial fractions and whole-cell compartments derived from cultured rat astroglia engineered to over-express human (h) HO-1 by transient transfection. Cell viability was assessed by trypan blue exclusion and the MTT assay, and cell proliferation was determined by [3H] thymidine incorporation and total cell counts. In rat astrocytes, hHO-1 over-expression (x 3 days) resulted in significant oxidative damage to mitochondrial lipids, proteins, and nucleic acids, partial growth arrest, and increased cell death. These effects were attenuated by incubation with 1 microM tin mesoporphyrin, a competitive HO inhibitor, or the iron chelator, deferoxamine. Up-regulation of HO-1 engenders oxidative mitochondrial injury in cultured rat astroglia. Heme-derived ferrous iron and carbon monoxide (CO) may mediate the oxidative modification of mitochondrial lipids, proteins and nucleic acids in these cells. Glial HO-1 hyperactivity may contribute to cellular oxidative stress, pathological iron deposition, and bioenergetic failure characteristic of degenerating and inflamed neural tissues and may constitute a rational target for therapeutic intervention in these conditions.
Song
Wei
W
Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada.
Su
Haixiang
H
Song
Sisi
S
Paudel
Hemant K
HK
Schipper
Hyman M
HM
D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000201:enzymology* / Q000648:ultrastructure; D049109:Cell Proliferation; D002470:Cell Survival; D051547:Heme Oxygenase-1 / Q000502:physiology*; D006801:Humans; D008928:Mitochondria / Q000201:enzymology*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D051381:Rats; D017207:Rats, Sprague-Dawley; D014162:Transfection; D015854:Up-Regulation
D051547:Heme Oxygenase-1