title: Gene regulation induced in the C57BL/6J mouse retina by hyperoxia: a temporal microarray study.
abstract: OBJECTIVE
  Hyperoxia is specifically toxic to photoreceptors, and this toxicity may be important in the progress of retinal dystrophies. This study examines gene expression induced in the C57BL/6J mouse retina by hyperoxia over the 14-day period during which photoreceptors first resist, then succumb to, hyperoxia.
  
  
  METHODS
  Young adult C57BL/6J mice were exposed to hyperoxia (75% oxygen) for up to 14 days. On day 0 (control), day 3, day 7, and day 14, retinal RNA was extracted and processed on Affymetrix GeneChip Mouse Genome 430 2.0 arrays. Microarray data were analyzed using GCOS Version 1.4 and GeneSpring Version 7.3.1. For 15 genes, microarray data were confirmed using relative quantitative real-time reverse transcription polymerase chain reaction techniques.
  
  
  RESULTS
  The overall numbers of hyperoxia-regulated genes increased monotonically with exposure. Within that increase, however, a distinctive temporal pattern was apparent. At 3 days exposure, there was prominent upregulation of genes associated with neuroprotection. By day 14, these early-responsive genes were downregulated, and genes related to cell death were strongly expressed. At day 7, the regulation of these genes was mixed, indicating a possible "transition period" from stability at day 3 to degeneration at day 14. When functional groupings of genes were analyzed separately, there was significant regulation in genes responsive to stress, genes known to cause human photoreceptor dystrophies and genes associated with apoptosis.
  
  
  CONCLUSIONS
  Microarray analysis of the response of the retina to prolonged hyperoxia demonstrated a temporal pattern involving early neuroprotection and later cell death, and provided insight into the mechanisms involved in the two phases of response. As hyperoxia is a consistent feature of the late stages of photoreceptor degenerations, understanding the mechanisms of oxygen toxicity may be important therapeutically.
authors.affiliation: ARC Centre of Excellence in Vision Science, The Australian National University, Canberra, Australia. riccardo.natoli@anu.edu.au
authors.forename: Riccardo
authors.initials: R
authors.lastname: Natoli
authors.forename: Jan
authors.initials: J
authors.lastname: Provis
authors.forename: Krisztina
authors.initials: K
authors.lastname: Valter
authors.forename: Jonathan
authors.initials: J
authors.lastname: Stone
mesh_terms: D000818:Animals; D016000:Cluster Analysis; D015536:Down-Regulation; D005786:Gene Expression Regulation; D006801:Humans; D018496:Hyperoxia / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D015203:Reproducibility of Results; D012160:Retina / Q000378:metabolism* / Q000473:pathology*; D012164:Retinal Diseases / Q000235:genetics; D013312:Stress, Physiological / Q000235:genetics; D013997:Time Factors; D015854:Up-Regulation