Comparative analysis of transcriptional profiles between two apoptotic pathways of light-induced retinal degeneration

• Published in: Neuroscience 2004, Vol.129 (3), p.779-790
• Main Authors: Roca, A., Shin, K.-J., Liu, X., Simon, M.I., Chen, J.
• Format: Article
• Language: English
• Subjects: Affymetrix GeneChip; albino mice; Animals; Apoptosis - physiology; Apoptosis - radiation effects; arrestin; Arrestin - deficiency; Arrestin - genetics; Biological and medical sciences; Blotting, Western - methods; Dark Adaptation - physiology; Eye and associated structures. Visual pathways and centers. Vision; Fundamental and applied biological sciences. Psychology; In Situ Hybridization - methods; Light - adverse effects; light damage; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Knockout; Microscopy, Electron, Transmission - methods; Oligonucleotide Array Sequence Analysis - methods; photoreceptor apoptosis; Photoreceptor Cells, Vertebrate - pathology; Photoreceptor Cells, Vertebrate - ultrastructure; Reproducibility of Results; retina; Retinal Degeneration - etiology; Retinal Degeneration - metabolism; Retinal Degeneration - pathology; Reverse Transcriptase Polymerase Chain Reaction - methods; RNA, Messenger - biosynthesis; Time Factors; Vertebrates: nervous system and sense organs
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/j.neuroscience.2004.08.021

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.