title: Ibuprofen protects alpha-crystallin against posttranslational modification by preventing protein cross-linking.
abstract: Posttranslational modification of bovine alpha-crystallin by D-erythrose-4-phosphate, fructose-6-phosphate, D-ribose-5-phosphate and carbamylation using potassium cyanate induced the loss of chaperone-like activity, as assessed by gamma-crystallin aggregation. The presence of high-molecular-weight aggregates indicated that erythrosylated, fructosylated and carbamylated alpha-crystallins were modified by non-reducible cross-linking. In contrast, ribosylation of alpha-crystallin induced the formation of reducible cross-links. Analysis of ribosylated, erythrosylated and carbamylated alpha-crystallin using non-denaturing acrylamide gels showed that the cross-linking did not sterically inhibit the normal aggregate formation or alter the oligomerisation of the aggregate. Co-incubation of ibuprofen in the presence of alpha-crystallin and the modifying agents protected the chaperone-like activity of alpha-crystallin, enabling the inhibition of gamma-crystallin aggregation. In addition, ibuprofen inhibited the formation of both reducible and non-reducible cross-linked high-molecular-weight alpha-crystallin aggregates. We show in this paper that ibuprofen can inhibit in vitro cross-linking events responsible for the loss of chaperone-like activity of alpha-crystallin and suggest that the protective effect of ibuprofen may be exerted by the binding of ibuprofen breakdown products to alpha-crystallin lysine groups, preventing posttranslational modification responsible for the loss of chaperone-like activity.
authors.affiliation: Division of Cell and Molecular Biology, School of Animal and Microbial Sciences, University of Reading, UK.
authors.forename: M L
authors.initials: ML
authors.lastname: Plater
authors.forename: D
authors.initials: D
authors.lastname: Goode
authors.forename: M J
authors.initials: MJ
authors.lastname: Crabbe
mesh_terms: D000818:Animals; D002417:Cattle; D003459:Crystallins / Q000187:drug effects / Q000378:metabolism*; D003485:Cyanates / Q000494:pharmacology; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D005636:Fructosephosphates / Q000494:pharmacology; D007052:Ibuprofen / Q000494:pharmacology*; D066298:In Vitro Techniques; D007908:Lens, Crystalline / Q000187:drug effects / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D012267:Ribosemonophosphates / Q000494:pharmacology; D013403:Sugar Phosphates / Q000494:pharmacology
chemical_list: D003459:Crystallins; D003485:Cyanates; D016861:Cyclooxygenase Inhibitors; D005636:Fructosephosphates; D018832:Molecular Chaperones; D012267:Ribosemonophosphates; D013403:Sugar Phosphates; C031626:ribose-5-phosphate; C026959:erythrose 4-phosphate; C027618:fructose-6-phosphate; C024835:potassium cyanate; D007052:Ibuprofen