Abstract
Purpose: :
The purpose of this investigation is to gain insight into the role of Peptidyl arginine deiminase 2 (PAD2) and protein deimination in multiple sclerosis (MS) retinas. Elevated PAD2, enzyme, that converts protein-bound arginine to citrulline (deimination) have been previously reported in MS.
Methods: :
Western and immunohistochemical analyses measured PAD2 expression and protein deimination in MS (ND4 mouse) and control mouse retina (10 animals each) and human retinas (10 each control and MS). Select proteins from retinal ganglion cells of control eyes were identified by liquid chromatography tandem mass spectrometry following immunoprecipitation using antibodies that bind to deiminated proteins. The studies were performed adhering to declaration of tenets of Helsinki and ARVO statement for animal use in Ophthalmic and visual research.
Results: :
Elevated PAD2 and protein deimination was found in MS mouse retina in contrast to controls by immunohistochemistry and were also confirmed by Western analysis. However, closer examination of MS eyes (mouse and human) in contrast to controls showed decreased protein deimination in retinal ganglion cell layer initially by immunohistochemistry and was confirmed by Western analysis.
Conclusions: :
Our results revealed the presence of local hypodeimination in MS retinal ganglion cells in addition to global hyperdeimination in the retina. We have further identified two proteins that undergo loss of deimination in MS.
Keywords: protein modifications-post translational • inner retina dysfunction: biochemistry and cell biology • retina