Proteomic analysis of the retina: removal of RPE alters outer segment assembly and retinal protein expression.

Wang X, Nookala S, Narayanan C, Giorgianni F, Beranova-Giorgianni S, McCollum G, Gerling I, Penn JS, Jablonski MM
Glia. 2009 57 (4): 380-92

PMID: 18803304 · PMCID: PMC2653273 · DOI:10.1002/glia.20765

The mechanisms that regulate the complex physiological task of photoreceptor outer segment assembly remain an enigma. One limiting factor in revealing the mechanism(s) by which this process is modulated is that not all of the role players who participate in this process are known. The purpose of this study was to determine some of the retinal proteins that likely play a critical role in regulating photoreceptor outer segment assembly. To do so, we analyzed and compared the proteome map of tadpole Xenopus laevis retinal pigment epithelium (RPE)-supported retinas containing organized outer segments with that of RPE-deprived retinas containing disorganized outer segments. Solubilized proteins were labeled with CyDye fluors followed by multiplexed two-dimensional separation. The intensity of protein spots and comparison of proteome maps was performed using DeCyder software. Identification of differentially regulated proteins was determined using nanoLC-ESI-MS/MS analysis. We found a total of 27 protein spots, 21 of which were unique proteins, which were differentially expressed in retinas with disorganized outer segments. We predict that in the absence of the RPE, oxidative stress initiates an unfolded protein response. Subsequently, downregulation of several candidate Müller glial cell proteins may explain the inability of photoreceptors to properly fold their outer segment membranes. In this study, we have used identification and bioinformatics assessment of proteins that are differentially expressed in retinas with disorganized outer segments as a first step in determining probable key molecules involved in regulating photoreceptor outer segment assembly.

MeSH Terms (16)

Animals Computational Biology Electrophoresis, Gel, Two-Dimensional Eye Proteins Gene Expression Regulation Larva Mass Spectrometry Models, Biological Neuroglia Organ Culture Techniques Proteomics Receptor-Like Protein Tyrosine Phosphatases, Class 2 Retina Retinal Photoreceptor Cell Outer Segment Retinal Pigment Epithelium Xenopus

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