title: Proteins modified by malondialdehyde, 4-hydroxynonenal, or advanced glycation end products in lipofuscin of human retinal pigment epithelium.
abstract: OBJECTIVE
  Lipofuscin (LF) accumulation in the retinal pigment epithelium (RPE) is associated with age and various retinal diseases. Toxic LF compounds may interfere with normal RPE function. Oxidative modification of proteins was determined in LF granules from human eyes.
  
  
  METHODS
  LF was isolated from the RPE-choroid complex of 10 pairs of donor eyes by gradient ultracentrifugation. Protein compounds were separated by two-dimensional (2-D) gel electrophoresis and screened by Western blot analysis for lipid peroxidation- or glucoxidation-induced damage-in particular, by malondialdehyde (MDA), 4-hydroxynonenal (HNE), and advanced glycation end products (AGEs). Identity of the immunostained proteins was revealed using 2-D software for comparison of the spot position with Coomassie-stained 2-D gels of the same samples.
  
  
  RESULTS
  By comparing the results taken from the authors' previous proteome analysis of RPE LF with an immunoblot analysis of the same samples, this study shows that a variety of LF-associated proteins were damaged by aberrant covalent modifications of MDA, 4-HNE, and AGEs. Several proteins were altered by two or three different modification types. Modified mitochondrial proteins indicated that autophagy of altered proteins also contributed to lipofuscin formation.
  
  
  CONCLUSIONS
  The identification of lipid peroxidation and glucoxidation products in proteinaceous LF components in human RPE supports the hypothesis that these compounds are involved in lipofuscinogenesis and may contribute to the cytotoxic effects of LF in retinal diseases such as age-related macular degeneration and Stargardt disease. Their identification may help to identify potential future treatment targets.
authors.affiliation: Department of Ophthalmology, University of Heidelberg, Heidelberg, Germany. florian_schuett@med.uni-heidelberg.de
authors.forename: Florian
authors.initials: F
authors.lastname: Schutt
authors.forename: Marion
authors.initials: M
authors.lastname: Bergmann
authors.forename: Frank G
authors.initials: FG
authors.lastname: Holz
authors.forename: Jurgen
authors.initials: J
authors.lastname: Kopitz
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000447:Aldehydes / Q000494:pharmacology*; D015153:Blotting, Western; D015180:Electrophoresis, Gel, Two-Dimensional; D005136:Eye Proteins / Q000378:metabolism; D017127:Glycation End Products, Advanced / Q000494:pharmacology*; D006801:Humans; D015227:Lipid Peroxidation; D008062:Lipofuscin / Q000302:isolation & purification / Q000378:metabolism*; D008315:Malondialdehyde / Q000494:pharmacology*; D010084:Oxidation-Reduction; D010857:Pigment Epithelium of Eye / Q000187:drug effects* / Q000378:metabolism; D020543:Proteome / Q000378:metabolism
chemical_list: D000447:Aldehydes; D005136:Eye Proteins; D017127:Glycation End Products, Advanced; D008062:Lipofuscin; D020543:Proteome; D008315:Malondialdehyde; C027576:4-hydroxy-2-nonenal