Abstract
Purpose: :
Histone acetyltransferases (HATs) and histone deacetylases (HDACs) are known to regulate transcription by modifying the histones, thereby enabling or restricting the access of transcription factors to genomic DNA. We examined HAT and HDAC expression in developing murine retina and chick optic cup as a first step in understanding the epigenetic mechanisms regulating retinal development and disease.
Methods: :
Expression of HATs (p300, P/CAF) and class I (HDAC1, 2, 3 and 8) and class IV HDAC (HDAC11) in the optic cupwas determined at E15 (embryonic day 15) and P30 (postnatal day 30) in mice and E5, E8, and E18 in chick. For immunostaining, eyes were fixed in paraformaldehyde and embedded in 20% sucrose:OCT mixture (3:1 ratio) prior to cryosectioning at 10 µm. Immunostained sections were imaged by confocal fluorescence microscopy. For western blots, total proteins were isolated from retinas at the same developmental stages, separated on denaturing SDS polyacrylamide gels and detected using chemiluminescence.
Results: :
In both mouse and chick, HDACs showed nuclear localization, with the highest staining intensity throughout the inner retinal layers and decreasing expression in proliferating cells in the outer half of the optic cup. Immunostaining for p300 and P/CAF, was weaker at all stages examined, compared to the HDACs. Western blot analysis of developing chick retina confirmed that HDAC expression decreased with age, while HAT levels were low in early stages and increased with age.
Conclusions: :
The expression patterns of class I and IV HDACs and the HATs, P/CAF and p300, in the developing mouse and chick optic cup suggest a role for dynamic changes in histone acetylation and deacetylation during retinal differentiation.
Keywords: retinal development • gene/expression • immunohistochemistry