title: 3-Hydroxykynurenine and 3-hydroxyanthranilic acid generate hydrogen peroxide and promote alpha-crystallin cross-linking by metal ion reduction.
abstract: The kynurenine pathway catabolite 3-hydroxykynurenine (3HK) and redox-active metals such as copper and iron are implicated in cataractogenesis. Here we investigate the reaction of kynurenine pathway catabolites with copper and iron, as well as interactions with the major lenticular structural proteins, the alpha-crystallins. The o-aminophenol kynurenine catabolites 3HK and 3-hydroxyanthranilic acid (3HAA) reduced Cu(II)>Fe(III) to Cu(I) and Fe(II), respectively, whereas quinolinic acid and the nonphenolic kynurenine catabolites kynurenine and anthranilic acid did not reduce either metal. Both 3HK and 3HAA generated superoxide and hydrogen peroxide in a copper-dependent manner. In addition, 3HK and 3HAA fostered copper-dependent alpha-crystallin cross-linking. 3HK- or 3HAA-modifed alpha-crystallin showed enhanced redox activity in comparison to unmodified alpha-crystallin or ascorbate-modified alpha-crystallin. These data support the possibility that 3HK and 3HAA may be cofactors in the oxidative damage of proteins, such as alpha-crystallin, through interactions with redox-active metals and especially copper. These findings may have relevance for understanding cataractogenesis and other degenerative conditions in which the kynurenine pathway is activated.
authors.affiliation: Department of Psychiatry, and Genetics and Aging Unit, Massachusetts General Hospital, Charlestown 02129, USA.
authors.forename: L E
authors.initials: LE
authors.lastname: Goldstein
authors.forename: M C
authors.initials: MC
authors.lastname: Leopold
authors.forename: X
authors.initials: X
authors.lastname: Huang
authors.forename: C S
authors.initials: CS
authors.lastname: Atwood
authors.forename: A J
authors.initials: AJ
authors.lastname: Saunders
authors.forename: M
authors.initials: M
authors.lastname: Hartshorn
authors.forename: J T
authors.initials: JT
authors.lastname: Lim
authors.forename: K Y
authors.initials: KY
authors.lastname: Faget
authors.forename: J A
authors.initials: JA
authors.lastname: Muffat
authors.forename: R C
authors.initials: RC
authors.lastname: Scarpa
authors.forename: L T
authors.initials: LT
authors.lastname: Chylack
authors.forename: E F
authors.initials: EF
authors.lastname: Bowden
authors.forename: R E
authors.initials: RE
authors.lastname: Tanzi
authors.forename: A I
authors.initials: AI
authors.lastname: Bush
mesh_terms: D015095:3-Hydroxyanthranilic Acid / Q000378:metabolism*; D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism; D002386:Cataract / Q000209:etiology; D002417:Cattle; D003300:Copper / Q000378:metabolism; D003459:Crystallins / Q000378:metabolism*; D004563:Electrochemistry; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007501:Iron / Q000378:metabolism; D007737:Kynurenine / Q000031:analogs & derivatives* / Q000378:metabolism; D007908:Lens, Crystalline / Q000378:metabolism; D008670:Metals / Q000378:metabolism*; D010084:Oxidation-Reduction; D013481:Superoxides / Q000378:metabolism; D014364:Tryptophan / Q000378:metabolism
chemical_list: D003459:Crystallins; D008670:Metals; D013481:Superoxides; D015095:3-Hydroxyanthranilic Acid; C005045:3-hydroxykynurenine; D007737:Kynurenine; D003300:Copper; D014364:Tryptophan; D006861:Hydrogen Peroxide; D007501:Iron; D001205:Ascorbic Acid