Abstract
Purpose :
The emmetropization mechanism uses wavelength cues to regulate eye growth and refractive state, but how wavelengths cause alterations of scleral remodeling leading to changes in eye size is unclear. We tested the hypothesis that exposure to light wavelengths, known to produce opposite emmetropization responses, causes differential regulation of proteins in scleral fibroblasts.
Methods :
After euthanasia, tree shrew (Tupaia belangeri) eyes were enucleated, and the sclera was dissected in small fragments and cultured. We characterized scleral fibroblasts by immunofluorescence using established phenotypic markers (ACTA3, Coll I, Vim, FN1, Coll 3 pre-pro-peptide). The scleral fibroblasts in culture were then exposed to dark (0 lux), white light (1372 lux), blue light (461±12nm, 627 lux), and red light (628±12nm, 657 lux) for 12 hours. After treatment, whole-cell proteomic profiles were generated using mass spectrometry.
Results :
A total of 1253 proteins were identified; 956 were common across the four conditions. The number of unique proteins in dark, white, red, and blue lights was 26, 9, 10, and 5, respectively (Fig 1). The top differentially upregulated proteins in white light compared to dark were Keratin I and Nuclear mitotic apparatus protein 1 (fold change, FC>2.5, Fig 2A). Blue light caused an upregulation of Prelamin-A/C, Proteasome subunit β3, Ras-related protein Ral-A, Nck-associated protein1, COL1A2, and PGM5 (FC>2.5), while red light caused an upregulation of Inter-α (globulin) inhibitor H2 (ITIH2), α-2-macroglobulin (A2M), protein AHNAK2, and Hemoglobin α1 (FC>2.5). Relative to blue light, the top five upregulated proteins in red light were ITIH2, NUP205, A2M, Lactoferrin, and α-2-HS-glycoprotein (FC>2.5, Fig 2B).
Conclusions :
Altering the spectral composition of the ambient light produced differential changes in expression levels of several scleral fibroblast proteins. Our results suggest that the differential scleral remodeling responses to wavelengths of light might be mediated by proteomic alterations in scleral fibroblasts. The specific proteomic pathway leading to light-induced scleral remodeling in myopia remains to be investigated.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.