title: Apolipoprotein A-IV attenuates oxidant-induced apoptosis in mitotic competent, undifferentiated cells by modulating intracellular glutathione redox balance.
abstract: Oxidant-mediated modulation of the intracellular redox state affects the apoptotic cascade by altering the balance between cellular signals for survival and suicide. Apolipoprotein A-IV (Apo A-IV) is known to possess antioxidant-like activity. In the present study, we tested 1) whether Apo A-IV could influence redox-dependent apoptosis and, if so, 2) whether such an effect could be mediated by modulation of intracellular redox balance. Mitotic competent, undifferentiated PC-12 cells were incubated with either tert-butyl hydroperoxide (TBH) or diamide with or without preincubation with human Apo A-IV. Apo A-IV significantly decreased apoptosis produced by both TBH and diamide, and washout of A-IV before incubation with TBH and diamide did not eliminate its protective effect. Apo A-I had no such protective effect. The Apo A-IV effect was not blocked by D,L-buthionine-[S,R]-sulfoximine, but it was reversed by both dehydroisoandrosterone and transfection with an antisense oligodeoxynucleotide to glucose-6-phosphate dehydrogenase (G6PD). Apo A-IV abolished the transient, oxidant-induced rise in glutathione disulfide (GSSG) and cellular redox imbalance previously shown to initiate the apoptotic cascade. Apo A-IV had no effect on GSSG reductase activity, but it stimulated G6PD activity 10-fold. These results suggest a novel role for Apo A-IV in the regulation of intracellular glutathione redox balance and the modulation of redox-dependent apoptosis via stimulation of G6PD activity.
authors.affiliation: Dept. of Surgery, Louisiana State Univ. Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130, USA.
authors.forename: Heather L
authors.initials: HL
authors.lastname: Spaulding
authors.forename: Fumito
authors.initials: F
authors.lastname: Saijo
authors.forename: Richard H
authors.initials: RH
authors.lastname: Turnage
authors.forename: J Steven
authors.initials: JS
authors.lastname: Alexander
authors.forename: Tak Yee
authors.initials: TY
authors.lastname: Aw
authors.forename: Theodore J
authors.initials: TJ
authors.lastname: Kalogeris
mesh_terms: D000818:Animals; D016632:Apolipoprotein A-I / Q000494:pharmacology; D001054:Apolipoproteins A / Q000378:metabolism* / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002454:Cell Differentiation; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism*; D019803:Glutathione Disulfide / Q000378:metabolism; D006801:Humans; D008938:Mitosis; D016877:Oxidants / Q000494:pharmacology; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D016716:PC12 Cells; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D020122:tert-Butylhydroperoxide / Q000494:pharmacology
chemical_list: D016632:Apolipoprotein A-I; D001054:Apolipoproteins A; D016877:Oxidants; D011994:Recombinant Proteins; C022205:apolipoprotein A-IV; D020122:tert-Butylhydroperoxide; D005954:Glucosephosphate Dehydrogenase; D005978:Glutathione; D019803:Glutathione Disulfide