Abstract
Purpose:
Müller glial stem cells are responsible for the retinal regeneration observed in fish and amphibians after injury. The human retina contains a population of Müller glia with stem cell characteristics, but it is not known to undergo regeneration following disease. It may be possible that gliotic retina may express factors that prevent growth and differentiation of Müller glia in situ and this may be important to investigate in order to explore potential therapies to promote endogenous regeneration of the human retina. This study aimed to examine differences between the proteomic profiles of normal and gliotic human retinae and to compare these with the proteomic profile of Müller stem cells.
Methods:
Normal cadaveric and gliotic retina were obtained according to guidelines from the Local Ethics Committee at Moorfields Eye Hospital and the Institute of Ophthalmology. Gliotic specimens were obtained upon written consent from patients undergoing retinectomy at Moorfields Eye Hospital. Protein was extracted from Müller stem cell lines established in our laboratory. Differential protein profile expression was performed using Label-free proteomics by LC-MS/MS. Protein identification and bioinformatics analysis was performed using Protein Lynx Global Server (PLGS), and Non-Linear dynamics Progenesis software.
Results:
Proteomic analysis of human retinae identified a total of 478 proteins in the normal samples and 453 proteins in the gliotic retina. 15 proteins were shown to be >2fold upregulated and 150 proteins to be >2fold downregulated in the gliotic retinas compared to controls. Of those differentially expressed, synapsin, CD166, TRAP1, RKIP, reticulon4 and SOD may be of interest to investigate for their ability to modify Müller stem cell growth and differentiation in vitro. Analysis of Müller glial stem cell lines identified a total of 477 proteins, which included common Müller cell markers including Vimentin, glutamine synthetase, CRALBP, CD44 and GFAP, as well as the factors identified above.
Conclusions:
This proteomic-based study has identified proteins and signalling pathways that are upregulated during retinal gliosis. Investigation of these factors on the proliferation and neural differentiation of human Müller stem cell functions in vitro may provide important clues for the identification of novel approaches to promote endogenous repair mechanisms in retinal degenerative diseases.
Keywords: 663 proteomics •
687 regeneration •
603 Muller cells