Coordinated changes in classes of ribosomal protein gene expression is associated with light-induced retinal degeneration.
OBJECTIVE
To identify genes with altered expression levels in the degenerating retina in a light-induced retinal degeneration (LIRD) model.


METHODS
Adult Sprague-Dawley rats were exposed to intense green light for 4 hours. After this treatment, the retinas were excised, RNA was extracted, and a cDNA library was prepared. The cDNA library was differentially cross-screened with probes representing 0-hour and 4-hour light-exposed rat retina. Transcripts with altered expression levels were sequenced and expression was confirmed by Northern blot analysis. Gene-specific primers were designed and used to examine the expression levels of other genes involved in protein synthesis. Promoter sequences of the ribosomal-binding protein (Rbp) genes were analyzed for transcription-binding sites.


RESULTS
Of the 10,000 clones that were initially screened, 41 exhibited altered expression levels. Six of these corresponded to five known Rbp genes. Six additional Rbp genes were also examined. In total, 9 of 11 Rbp genes exhibited an increase in expression levels in response to a 4-hour light exposure. In contrast, the transcript levels of elongation factor 1alpha1 and 18S rRNA did not increase. The most abundant transcription factor-binding sites conserved in the promoter regions of all Rbp genes examined in this study include AP-1, Oct-1, V-myb, USF, Pax-4, and the FOX family of transcription factors.


CONCLUSIONS
The results indicate that light-induced retinal degeneration (LIRD) is associated with increased expression of specific Rbp genes. These Rbp genes may be involved in mediating visual cell loss in LIRD through a translational or an extraribosomal mechanism.
Grewal
Ruby
R
Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada. pwwong@ualbert.ca
Stepczynski
Jadwiga
J
Kelln
Rhonda
R
Erickson
Timothy
T
Darrow
Ruth
R
Barsalou
Linda
L
Patterson
Michelle
M
Organisciak
Daniel T
DT
Wong
Paul
P
D000818:Animals; D015152:Blotting, Northern; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D015723:Gene Library; D008027:Light; D008297:Male; D018384:Oxidative Stress; D016133:Polymerase Chain Reaction; D012313:RNA / Q000302:isolation & purification; D012337:RNA, Ribosomal, 18S / Q000378:metabolism; D011833:Radiation Injuries, Experimental / Q000235:genetics* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012160:Retina / Q000378:metabolism / Q000528:radiation effects*; D012162:Retinal Degeneration / Q000235:genetics* / Q000378:metabolism; D012269:Ribosomal Proteins / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics
D005136:Eye Proteins; D012337:RNA, Ribosomal, 18S; D012269:Ribosomal Proteins; D014157:Transcription Factors; D012313:RNA