title: Hemoglobin is present as a canonical α2β2 tetramer in dopaminergic neurons.
abstract: Hemoglobin is the oxygen carrier in blood erythrocytes. Oxygen coordination is mediated by α2β2 tetrameric structure via binding of the ligand to the heme iron atom. This structure is essential for hemoglobin function in the blood. In the last few years, expression of hemoglobin has been found in atypical sites, including the brain. Transcripts for α and β chains of hemoglobin as well as hemoglobin immunoreactivity have been shown in mesencephalic A9 dopaminergic neurons, whose selective degeneration leads to Parkinson's disease. To gain further insights into the roles of hemoglobin in the brain, we examined its quaternary structure in dopaminergic neurons in vitro and in vivo. Our results indicate that (i) in mouse dopaminergic cell line stably over-expressing α and β chains, hemoglobin exists as an α2β2 tetramer; (ii) similarly to the over-expressed protein, endogenous hemoglobin forms a tetramer of 64kDa; (iii) hemoglobin also forms high molecular weight insoluble aggregates; and (iv) endogenous hemoglobin retains its tetrameric structure in mouse mesencephalon in vivo. In conclusion, these results suggest that neuronal hemoglobin may be endowed with some of the biochemical activities and biological function associated to its role in erythroid cells. This article is part of a Special Issue entitled: Oxygen Binding and Sensing Proteins.
authors.affiliation: Institute of Protein Biochemistry, CNR, Via Pietro Castellino 111, Naples, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Russo
authors.forename: Silvia
authors.initials: S
authors.lastname: Zucchelli
authors.forename: Marta
authors.initials: M
authors.lastname: Codrich
authors.forename: Federica
authors.initials: F
authors.lastname: Marcuzzi
authors.forename: Cinzia
authors.initials: C
authors.lastname: Verde
authors.forename: Stefano
authors.initials: S
authors.lastname: Gustincich
mesh_terms: D000818:Animals; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D002478:Cells, Cultured; D003432:Cross-Linking Reagents / Q000378:metabolism; D059290:Dopaminergic Neurons / Q000166:cytology / Q000378:metabolism*; D006418:Heme / Q000378:metabolism*; D006454:Hemoglobins / Q000737:chemistry* / Q000378:metabolism*; D015151:Immunoblotting; D051379:Mice; D008810:Mice, Inbred C57BL; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology; D010100:Oxygen / Q000378:metabolism*; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary
chemical_list: D003432:Cross-Linking Reagents; D006454:Hemoglobins; D006418:Heme; D010100:Oxygen
keywords: Dopaminergic neurons; Hemoglobin; Mouse; Native structure