title: Sickle Cell Hemoglobin in the Ferryl State Promotes βCys-93 Oxidation and Mitochondrial Dysfunction in Epithelial Lung Cells (E10).
abstract: Polymerization of intraerythrocytic deoxyhemoglobin S (HbS) is the primary molecular event that leads to hemolytic anemia in sickle cell disease (SCD). We reasoned that HbS may contribute to the complex pathophysiology of SCD in part due to its pseudoperoxidase activity. We compared oxidation reactions and the turnover of oxidation intermediates of purified human HbS and HbA. Hydrogen peroxide (H2O2) drives a catalytic cycle that includes the following three distinct steps: 1) initial oxidation of ferrous (oxy) to ferryl Hb; 2) autoreduction of the ferryl intermediate to ferric (metHb); and 3) reaction of metHb with an additional H2O2 molecule to regenerate the ferryl intermediate. Ferrous and ferric forms of both proteins underwent initial oxidation to the ferryl heme in the presence of H2O2 at equal rates. However, the rate of autoreduction of ferryl to the ferric form was slower in the HbS solutions. Using quantitative mass spectrometry and the spin trap, 5,5-dimethyl-1-pyrroline-N-oxide, we found more irreversibly oxidized βCys-93in HbS than in HbA. Incubation of the ferric or ferryl HbS with cultured lung epithelial cells (E10) induced a drop in mitochondrial oxygen consumption rate and impairment of cellular bioenergetics that was related to the redox state of the iron. Ferryl HbS induced a substantial drop in the mitochondrial transmembrane potential and increases in cytosolic heme oxygenase (HO-1) expression and mitochondrial colocalization in E10 cells. Thus, highly oxidizing ferryl Hb and heme, the product of oxidation, may be central to the evolution of vasculopathy in SCD and may suggest therapeutic modalities that interrupt heme-mediated inflammation.
authors.affiliation: From the Laboratory of Biochemistry and Vascular Biology, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland 20993 and.
authors.forename: Tigist
authors.initials: T
authors.lastname: Kassa
authors.affiliation: From the Laboratory of Biochemistry and Vascular Biology, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland 20993 and.
authors.forename: Sirsendu
authors.initials: S
authors.lastname: Jana
authors.affiliation: From the Laboratory of Biochemistry and Vascular Biology, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland 20993 and.
authors.forename: Michael Brad
authors.initials: MB
authors.lastname: Strader
authors.affiliation: From the Laboratory of Biochemistry and Vascular Biology, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland 20993 and.
authors.forename: Fantao
authors.initials: F
authors.lastname: Meng
authors.affiliation: From the Laboratory of Biochemistry and Vascular Biology, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland 20993 and.
authors.forename: Yiping
authors.initials: Y
authors.lastname: Jia
authors.affiliation: the Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Wilson
authors.affiliation: From the Laboratory of Biochemistry and Vascular Biology, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland 20993 and abdu.alayash@fda.hhs.gov.
authors.forename: Abdu I
authors.initials: AI
authors.lastname: Alayash
mesh_terms: D000743:Anemia, Hemolytic / Q000201:enzymology; D000755:Anemia, Sickle Cell / Q000201:enzymology; D002384:Catalysis; D003497:Cyclic N-Oxides / Q000737:chemistry; D003545:Cysteine / Q000737:chemistry*; D004734:Energy Metabolism; D006418:Heme / Q000737:chemistry; D006419:Heme Oxygenase (Decyclizing) / Q000737:chemistry; D006451:Hemoglobin, Sickle / Q000737:chemistry*; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D008168:Lung / Q000201:enzymology; D008706:Methemoglobin / Q000737:chemistry; D008928:Mitochondria / Q000378:metabolism*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D020545:Respiratory Mucosa / Q000201:enzymology* / Q000648:ultrastructure
chemical_list: D003497:Cyclic N-Oxides; D006451:Hemoglobin, Sickle; C066317:ferryl iron; D006418:Heme; C017245:5,5-dimethyl-1-pyrroline-1-oxide; D008706:Methemoglobin; D006861:Hydrogen Peroxide; D007501:Iron; D006419:Heme Oxygenase (Decyclizing); D003545:Cysteine
keywords: bioenergetics; hemoglobin; mitochondria; oxidative stress; oxygen radicals