title: Early changes in gene expression induced by blue light irradiation of A2E-laden retinal pigment epithelial cells.
abstract: OBJECTIVE
  Accumulation of bisretinoids as lipofuscin in retinal pigment epithelial (RPE) cells is implicated in the pathogenesis of some blinding diseases including age-related macular degeneration (AMD). To identify genes whose expression may change under conditions of bisretinoid accumulation, we investigated the differential gene expression in RPE cells that had accumulated the lipofuscin fluorophore A2E and were exposed to blue light (430 nm).
  
  
  METHODS
  A2E-laden RPE cells were exposed to blue light (A2E/430 nm) at various time intervals. Cell death was quantified using Dead Red staining, and RNA levels for the entire genome was determined using DNA microarrays (Affymetrix GeneChip Human Genome 2.0 Plus). Array results for selected genes were confirmed by real-time reverse-transcriptase polymerase chain reaction.
  
  
  RESULTS
  Principal component analysis revealed that the A2E-laden RPE cells irradiated with blue light were clearly distinguishable from the control samples. We found differential regulation of genes belonging to the following functional groups: transcription factors, stress response, apoptosis and immune response. Among the last mentioned were downregulation of four genes that coded for proteins that have an inhibitory effect on the complement cascade: (complement factor H, complement factor H-related 1, complement factor I and vitronectin) and of two belonging to the classical pathway (complement component 1, s subcomponent and complement component 1, r subcomponent).
  
  
  CONCLUSIONS
  This study demonstrates that blue light irradiation of A2E-laden RPE cells can alter the transcription of genes belonging to different functional pathways including stress response, apoptosis and the immune response. We suggest that these molecules may be associated to the pathogenesis of AMD and can potentially serve as future therapeutic targets.
authors.affiliation: Department of International Health, Immunology and Microbiology, Eye Research Unit, University of Copenhagen, Copenhagen, DenmarkDepartment of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, DenmarkDepartment of Ophthalmology, Columbia University, New York, New York, USA.
authors.forename: Barbro W
authors.initials: BW
authors.lastname: van der Burght
authors.forename: Morten
authors.initials: M
authors.lastname: Hansen
authors.forename: Jørgen
authors.initials: J
authors.lastname: Olsen
authors.forename: Jilin
authors.initials: J
authors.lastname: Zhou
authors.forename: Yalin
authors.initials: Y
authors.lastname: Wu
authors.forename: Mogens H
authors.initials: MH
authors.lastname: Nissen
authors.forename: Janet R
authors.initials: JR
authors.lastname: Sparrow
mesh_terms: D017209:Apoptosis; D002460:Cell Line; D002470:Cell Survival; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D008027:Light; D008062:Lipofuscin / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D025341:Principal Component Analysis; D011726:Pyridinium Compounds; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D055213:Retinal Pigment Epithelium / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects*; D012176:Retinoids / Q000235:genetics*; D059467:Transcriptome
chemical_list: C112040:A2-E (N-retinylidene-N-retinylethanolamine); D008062:Lipofuscin; D011726:Pyridinium Compounds; D012333:RNA, Messenger; D012176:Retinoids
keywords: A2E; age-related macular degeneration; apoptosis; complement cascade; gene expression; retinal pigment epithelial cells