Identification of Myopia-Related Marker Proteins in Tilapia Retinal, RPE, and Choroidal Tissue following Induced Form Deprivation

Abstract

Purpose: Experimentally induced myopia is characterized by axial elongation of the eye. The molecular pathways leading to this condition are largely unknown, even though many candidate proteins have been proposed to be involved in this process. This study has identified proteins that were differentially expressed in myopic and control combined retina, retinal pigment epithelium (RPE), and choroidal tissue in tilapia (Oreochromis niloticus).

Methods: Form deprivation was used to induce myopia in tilapia (n = 3). In this initial study on tilapia retina, RPE and choroid, 2-D differential in gel electrophoresis (DIGE) and mass spectrometry were used to identify differentially expressed proteins. Homology-based gene cloning was used to obtain full sequence data for one of the identified proteins.

Results: A total of 18 protein spots separated by 2-D electrophoresis exhibited statistically significant differences in expression between the myopic and contralateral control combined retinal, RPE, and choroidal tissue. Three proteins were identified at a significance level of p < 0.05, as annexin A5 (down-regulated 47%), Gelsolin (down-regulated 27%), and TCP-1 (CCT) (down-regulated 54%). DNA sequencing of tilapia annexin A5 shows an amino acid sequence identity of 84.5% with the homologous Japanese ricefish annexin max2.

Conclusions: A proteomics approach has been used to identify differentially expressed proteins in form-deprived combined retinal, RPE, and choroidal tissue from myopic versus normal eyes. The identified proteins may be components of pathways involved in myopia pathogenesis.

KEYWORDS::

• Animal model
• Form deprivation
• Myopia
• Proteomics
• Tilapia

ACKNOWLEDGMENTS

Authors W. Shen and J. T. A. Barrows contributed equally to experiments and manuscript preparation. The authors thank Nancy Gibson for assistance with animals during the study, Andrea Spires for her assistance with mass spectrometry sample preparation and analysis, and Catherine Walden with manuscript preparation. This work was supported by grants from the Natural Sciences and Engineering Research Council of Canada (TDS, BJM, and JGS) and the CNIB E. A. Baker Award (TDS).

Declaration of interest: The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.