Abstract
Purpose: :
Increased deimination and Peptidylarginine deiminase type 2 (PAD2) expression has been observed in age-related neurodegenerative diseases without discrimination between their aging and disease component. To better understand late-onset and progressive diseases such as glaucoma, pseudoexfoliation syndrome and age-related macular degeneration (AMD) we studied protein deimination levels in aged F344BN rat retina.
Methods: :
The F344BN rats, at ages 3 and 24 months (n= 6 each) were used for these studies following protocols confirming adherence to the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research. Freshly enucleated eyes were subjected to Western, Northern and immunohistochemical detection using antibodies to PAD2 and MAP2, Thy-1, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and farnesyl. ELISA was performed to detect serum levels of protein-bound citrulline using a kit (Upstate Biotechnology, New York).
Results: :
The retina and the optic nerve of the F344BN rats showed statistically significant decreased levels of deiminated proteins in the older (24 months) compared with the young (3 months) F344BN rats far exceeding the loss in retinal ganglion cells in older animals (detected by markers such as Thy1). Commensurate with protein deimination, a decreased PAD2 immunoreactivity and mRNA was found in the older F344BN retinas compared to the young.
Conclusions: :
An age-associated decrease in deiminated protein, PAD2 protein and PAD2 mRNA was found in the F344BN retinas. These results will encourage investigation for deciphering role of deimination and consequences of its loss in older animals.
Keywords: aging • protein modifications-post translational • retina