title: Crucial role of lysosomal iron in the formation of dinitrosyl iron complexes in vivo.
abstract: Dinitrosyl non-heme-iron complexes (DNIC) are found in many nitric oxide producing tissues. A prerequisite of DNIC formation is the presence of nitric oxide, iron and thiol/imidazole groups. The aim of this study was to investigate the role of the cellular labile iron pool in the formation of DNIC in erythroid K562 cells. The cells were treated with a nitric oxide donor in the presence of a permeable (salicylaldehyde isonicotinoyl hydrazone) or a nonpermeable (desferrioxamine mesylate) iron chelator and DNIC formation was recorded using electron paramagnetic resonance. Both chelators inhibited DNIC formation up to 50% after 6 h of treatment. To further investigate the role of lysosomal iron in DNIC formation, we prevented lysosomal proteolysis by pretreatment of whole cells with NH4Cl. Pretreatment with NH4Cl inhibited the formation of DNIC in a time-dependent manner that points to the importance of the degradation of iron metalloproteins in DNIC formation in vivo. Fractionation of the cell content after treatment with the nitric oxide donor revealed that DNIC is formed predominantly in the endosomal/lysosomal fraction. Taken together, these data indicate that lysosomal iron plays a crucial role in DNIC formation in vivo. Degradation of iron-containing metalloproteins seems to be important for this process.
authors.affiliation: Department of Radiobiology and Health Protection, Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195, Warsaw, Poland.
authors.forename: Hanna
authors.initials: H
authors.lastname: Lewandowska
authors.forename: Sylwia
authors.initials: S
authors.lastname: Meczyńska
authors.forename: Barbara
authors.initials: B
authors.lastname: Sochanowicz
authors.forename: Jarosław
authors.initials: J
authors.lastname: Sadło
authors.forename: Marcin
authors.initials: M
authors.lastname: Kruszewski
mesh_terms: D000447:Aldehydes / Q000494:pharmacology; D000643:Ammonium Chloride / Q000494:pharmacology; D002458:Cell Fractionation; D002460:Cell Line; D003676:Deferoxamine / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D006801:Humans; D006835:Hydrazones / Q000494:pharmacology; D007501:Iron / Q000378:metabolism*; D007502:Iron Chelating Agents / Q000737:chemistry; D008247:Lysosomes / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009589:Nitrogen Oxides / Q000378:metabolism*
chemical_list: D000447:Aldehydes; D006835:Hydrazones; D007502:Iron Chelating Agents; D020030:Nitric Oxide Donors; D009589:Nitrogen Oxides; C413684:salicylaldehyde isonicotinoyl hydrazone; D000643:Ammonium Chloride; C073661:dinitrosyl iron complex; D007501:Iron; D003676:Deferoxamine