Abstract
Purpose :
Protective effect of NA on LIM eye growth in chicks was reported previously. To understand the underlying biological mechanism, protein profiling of the myopic chick retinas in response to oral intake of NA was studied by label free SWATH-MS.
Methods :
White Leghorn chicks at 4 days old (PN4) were randomly allocated into 2 groups (treatment: n=8; control: n=8). A single dose of 1ml NA (150mg) was orally fed daily in treatment group, while the control chicks received saline orally for 10 days (PN4 to PN14). At PN10, -10D lenses were attached to both eyes of all chicks. The refractive errors and ocular parameters were examined on PN10 and PN14. The changes of refractive errors and ocular parameters before and after the treatment were analyzed by t-test (SPSS 23.0). The retinal samples were collected on PN14. Differentially expressed proteins between 2 groups were identified and quantified by LC-MS/MS.
Results :
After 4 days of lens wear, chicks in the treatment group became significantly less myopic than the controls, the changes of refractive error (treatment vs. control; -5.563±0.513D vs. -8.875±0.463D; p<0.001), vitreous chamber depth (0.548±0.146mm vs. 0.713±0.084mm; p=0.015), and axial length (0.801±0.172mm vs. 0.983±0.093mm; p=0.024) were all significant. A total of 4832 proteins were identified (at 1% FDR) which formed a chick retinal proteome library for SWATH data analysis. Thirty differentially expressed proteins were found (p<0.05; fold changes > 1.3 folds with not less than 2 peptides). According to bioinformatics analysis, the top 5 identified pathways were insulin resistance, regulation of actin cytoskeleton, insulin signaling, endocytosis and phototransduction.
Conclusions :
Oral intake of NA retarded myopic development in LIM chicks. Proteomic approach help identify differentially expressed proteins in response of NA intake, and the potential pathways that involved. For examples, GYS2 was differentially expressed which is involved in both insulin resistance and insulin signaling pathways, and these 2 pathways were previously reported in modulating eye growth. ARPC1A and GRK1 which involved in endocytosis pathway were found significantly changed. Our results suggested possible underlying pathways which may be involved in the protective effect of NA on myopic eye growth. New candidate proteins were identified for further confirmation.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.