Abstract
Purpose: :
The AP–1 transcription factor plays an important role in regulating gene expression, and is activated in the process of photoreceptor degeneration. We examined the AP–1 DNA binding activity in affected retinas from dogs having a frameshift mutation of RPGR ORF15 to gain a better understanding of the molecular regulation of retinal degeneration.
Methods: :
The retina tissue samples were collected from RPGR mutant dogs at 4, 6, 7, 9, 11 and 12 weeks, and the nuclear protein extracts were prepared. DNA binding activity of AP–1 was examined by electrophoretic mobility shift assay (EMSA). Retinal nuclear protein extracts from mutant dogs were hybridized with the labeled AP–1 consensus oligonucleotide, then analyzed with 2–20% gradient polyacrylamide gels. The AP–1 complex was detected as the shifted band, and the DNA binding activity of AP–1 was identified based on the intensity of the shifted bands.
Results: :
Increased AP–1 DNA binding activity was identified in RPGR mutant dog retinas; the elevation of binding activity parallels the time course of photoreceptor degeneration.
Conclusions: :
Analysis of retinal nuclear protein samples indicated that AP–1 DNA binding activity was induced in mutant dogs during the photoreceptor degeneration process. This result can support the hypothesis that increased AP–1 activity prior to and during apoptosis reflects increased expression of pro–apoptotic target genes. Further investigation on the induction of AP–1 DNA binding activity, the composition of the AP–1 protein complex, and the target genes transactivated by AP–1 will provide insights into the molecular mechanism of photoreceptor degeneration.
Keywords: transcription factors • retina • degenerations/dystrophies