Comparative analysis of transcriptional profiles between two apoptotic pathways of light-induced retinal degeneration.
Light exposure can exacerbate the condition of a variety of human retinal diseases by increasing the rate of photoreceptor cell death. How light negatively affects photoreceptor cell survival is not yet fully understood. Previous studies involving light damage models have revealed two independent apoptotic pathways: low levels of light induce retinal degeneration in the arrestin -/- mouse via constitutive activation of the phototransduction cascade, whereas strong light exposure to the retina, such as in an albino eye, elicits photoreceptor cell death via activator protein (AP-1) induction. In order to better understand the initial gene expression changes underlying light damage, dark-reared arrestin -/- and albino BALB/c mice were exposed to constant white light (2000 lux), and their retinal morphology was assessed as a function of time. The expression profiles of retinal transcripts were then compared between dark-adapted and light-exposed arrestin -/-, pigmented wild-type and BALB/c mice at a time point when morphological changes were minimal. As expected, the dark-adapted samples showed little difference in expression pattern between the three genotypes. Among the genes differentially regulated by light in BALB/c, but not arrestin -/- retinas, were c-fos and other stress-induced early response genes. In both mouse models, a marked increase in expression of the bZIP family of transcription factors was observed. Our results show a select group of unique and overlapping sets of genes induced by light in the two mouse models. These expression changes may constitute the underlying initiating events leading to the two distinct mechanisms of light damage.
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Zilkha Neurogenetic Institute, The Mary D. Allen Laboratory for Vision Research, Beckman Macular Research Center, University of Southern California Keck School of Medicine, 1501 San Pablo Street, Los Angeles, CA 90033, USA.
Shin
K-J
KJ
Liu
X
X
Simon
M I
MI
Chen
J
J
D000818:Animals; D017209:Apoptosis / Q000502:physiology* / Q000528:radiation effects; D019393:Arrestin / Q000172:deficiency / Q000235:genetics; D015153:Blotting, Western / Q000379:methods; D003623:Dark Adaptation / Q000502:physiology; D017403:In Situ Hybridization / Q000379:methods; D008027:Light / Q000009:adverse effects*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D046529:Microscopy, Electron, Transmission / Q000379:methods; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D020419:Photoreceptor Cells, Vertebrate / Q000473:pathology* / Q000648:ultrastructure; D012333:RNA, Messenger / Q000096:biosynthesis; D015203:Reproducibility of Results; D012162:Retinal Degeneration / Q000209:etiology* / Q000378:metabolism* / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013997:Time Factors
D019393:Arrestin; D012333:RNA, Messenger