Relative protein quantification in lens-induced chick retina by iTRAQ-based proteomics approach

Myopia is a leading cause of preventable blindness.It is reported that retina accepts optical signals to guide the emmetropization process.Recent animal studies have focused in examining the biochemical mechanism involved in the regulation of axial elongation.Here we aim to use iTRAQ approach coupled with tandem MS to profile dynamic retinal protein expressions in response to the short-term lens-induced chick myopia. 5-day old chicks were treated monocularly with -5D lenses(LIM).(RE:treated eye;LE:contralateral control eye).They were reared under a 12:12 hour light/dark cycle.Refraction and axial length were taken using retinoscopy and A-scan respectively.The chicks were sacrificed after LIM treatments for 4 days(n=8),and 6 days(n=6) before the eyes were fully compensated.The eyeball were hemisected immediately to harvest the retina.At each time point,soluble proteins were pooled randomly as 2 biological groups for each of the treatment and control group.After tryptic digestion and iTRAQ labelling,LC-MS/MS was perfomed on a Triple-TOF followed by bioinformatics analysis to investigate the differential protein expressions between the myopic and control eyes. Significant myopic eye growth was induced using -5D treatment. The change of axial length compared to baseline after 4-day LIM was 0.40±0.02 mm vs 0.17±0.02mm, (RE vs LE, p<0.01); the change of 6-day LIM was 0.60±0.03 mm vs 0.27±0.03mm, (RE vs LE, p<0.01). For refraction, significant myopia was induced in the RE: -2.83±0.25 D and -3.93±0.42 D after 4-day and 6-day LIM respectively. With a cutoff threshold for protein expression at >1.3-fold in both biological replicates, there were 58 proteins found differentially expressed among 1988 identified retinal proteins (FDR <0.01) after 4-day LIM, while after 6-day LIM, 136 proteins were found differentially expressed among 2710 proteins. Four proteins, Catenin beta-1, cAMP responsive element binding protein 1, Endoplasmin and Superoxide dismutase, were found significantly up-regulated between the two treatment time points (6-day LIM minus 4-day LIM). They belong to cAMP pathway and Wnt/-catenin pathway that were recently proposed by our group and others. Our data supported that retinal cAMP pathway and Wnt/-catenin pathway may be involved in the axial elongation in myopia. iTRAQ-based proteomics study has suggested potential protein targets for future myopia study. This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.