Abstract
Purpose: :
Myopia can be induced in the mouse using a spectacle lens procedure. The purpose of this study was to determine if the retina of eyes with experimental myopia show differences in the retina proteome.
Methods: :
Contact lenses were placed over the right eyes of 6 Balb/c mice by attaching a negative (-10D) contact lens over the eye on post-natal day 10. Axial length was measured by AC-Master, OLCI (Carl-Zeiss) and refraction was measured by retinoscopy at 4, 6 and 8 weeks. Mouse retina at 8 weeks was carefully removed from RPE and choroid under a dissecting microscope. Some tissues underwent paraffin embedding to ensure that the retina was removed in± isolation. A quantitative proteomic procedure using iTRAQ (isobaric tags for relative and absolute quantitation) combined with two-dimensional nano-liquid chromatography-nano-electrospray ionization-tandem mass spectrometry to perform a differential analysis of the retina proteome comparing myopic eyes with fellow control eyes. Retina samples used were separately pooled from six eyes with spectacle lens-induced myopia group and the fellow control eyes respectively. ProteinPilot software was used for relative protein quantitation.
Results: :
The refractions in eyes with lenses were -4.3D ± -1.06D (Mean ±SD) with an axial length of 3.69mm ± 0.07mm while the refraction in fellow eyes was 7.2D ± 1.22D and an axial length of 3.34mm ± 0.05mm. In total, close to 200 proteins were identified in the retina proteome with a 95% confidence, of which 18 proteins were found to be up-regulated (ratio of myopia:contrrol > 1.25) and 10 proteins were down-regulated (ratio of myopia:control < 0.8). Differentially expressed proteins included rhodopsin, delta-aminolevulinic acid dehydratase, acidic leucine-rich nuclear phosphoprotein 32E, crystallin, glyoxalase domain-containing protein 4, retinoschisin, voltage-dependent anion-selective channel protein 3, diazepam binding inhibitor isoform 1, Sod2 superoxide dismutase, creatine kinase M-type, and vimentin. Ontology showed that their biological or molecular functions were associated with phototransduction, cerebellar development and synaptogenesis, retinal development, acyl-CoA binding, response to oxidative stress, energy transduction in tissues, as well as some structural components.
Keywords: retina • proteomics • myopia