Gene Expression and Pathways Underlying Form Deprivation Myopia in the Guinea Pig Sclera

Posterior scleral remodeling accompanies myopia. In guinea pigs developing myopia, the region around the optic nerve (peripapillary zone, PPZ) rapidly expands followed by inhibition in eye size in the periphery. We studied the differential gene expression in the sclera that accompanies these changes.

Guinea pigs were form-deprived (FD) for 2 weeks to induce myopia, while the fellow eye served as a control. After 2 weeks, the PPZ and the peripheral temporal sclera were isolated in representative animals to extract the RNA. RNA sequencing was undertaken using an Illumina HiSeq 2000, with differential expression analyzed using Voom and pathways analyzed using the Ingenuity Pathway Analysis tool. RNA from additional PPZ and peripheral temporal sclera in FD and fellow eyes was used for validation of gene expression using quantitative real-time PCR (qRT-PCR).

In myopic sclera, 348 genes were differentially expressed between PPZ and the peripheral temporal region (corrected P < 0.05), of which 61 were differentially expressed in the PPZ between myopic and control eyes. Pathway analyses of these gene sets showed the involvement of Gαi signaling along with previously reported gamma-aminobutyric acid (GABA) and glutamate receptors among numerous novel pathways. The expression pattern of three novel genes and two myopia-related genes was validated using qRT-PCR.

Gene expression changes are associated with the rapid elongation that occurs around the optic nerve region during the development of myopia. A prominent change in Gαi signaling, which affects cAMP synthesis and thus collagen levels, may be critical in mediating the regional changes in myopic sclera.