Chicken peptidylarginine deiminase type I and III are constitutively expressed in the retinal neuron

• Published in: Acta ophthalmologica (Oxford, England) Vol. 91; no. s252
• Main Authors: SHIMIZU, A, HONDA, T, KOJIMA, T, KOHSAKA, T, TAKAHARA, H
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.08.2013; Wiley Subscription Services, Inc
• Subjects: Antibodies; Ophthalmology
• ISSN: 1755-375X; 1755-3768
• DOI: 10.1111/j.1755-3768.2013.F003.x

Purpose Peptidylarginine deiminase (PAD) is a post‐translational modification enzyme that catalyzes the conversion of protein‐bound arginine residues to citrulline residues in the presence of calcium ion. PAD genes are distributed generally throughout vertebrates. In chickens, three PAD genes have been identified and are orthologous to the mammalian genes encoding PAD1, PAD2 and PAD3, respectively. The expression levels and tissue/cellar location of each PAD under normal physiological conditions have not been elucidated as yet. Methods cPAD1 or cPAD3 specific antibodies were prepared from rabbits immunized with a synthetic peptide and used for western blot analyses and immunohistochemistry assays. To determine the intracellular localization of chicken PADs in retina cells, immunoelectron microscopy was also carried out. Whether or not the deiminated proteins were produced in retinal tissues was also examined by immunohistochemistry using an anti‐modified citrulline detection method. Results We found that both cPAD1 and cPAD3 are expressed in the chicken retina. cPAD1 was localized in the inner nuclear layer (INL) whereas cPAD3 was localized in the outer photoreceptor (OP). cPAD3 was present at especially high levels of detection in the lamella structure. Deiminated proteins were also detected in the INL and OP, suggesting that cPAD1 and cPAD3 function in the chicken retina under normal physiological conditions. Conclusion Our findings suggest that chicken PAD1 and PAD3 play a homeostatic role in the chicken retina in governing sight.