Bidirectional Phosphorylation Changes in Opsins Associated With Early Myopia and Hyperopia Signal Regulation by Phosphoproteomics

PURPOSE. The study aimed to investigate the role of post-translational modifications (PTMs), specifically phosphorylation, in the pathogenesis of lens-induced myopia (LIM) and lens-induced hyperopia (LIH). METHODS. This study used an untargeted phosphoproteomics approach to identify more than 12,000 phosphorylation sites in chick retinas. The changes in phosphorylation levels were quantified using the tandem mass tag (TMT) technique. Furthermore, targeted mass spectrometry was employed to characterize and validate the phosphorylation changes in visual opsins. RESULTS. The analysis identified differential phosphorylation at specific sites: S334 in rhodopsin, S328 in violet-sensitive opsin, and S342 in blue-sensitive opsin. Notably, these serine residues were dephosphorylated during the onset of myopia, but they remained phosphorylated under hyperopic conditions. This finding indicates that phosphorylation patterns in opsins are significantly modulated by changes in optical conditions, potentially influencing retinal signaling pathways. CONCLUSIONS. The findings highlight the bidirectional modulation of phosphorylation in opsins as a potential mechanism linking optical factors from induced myopia and hyperopia to the molecular signaling processes that regulate ocular growth and adaptation.