A microRNA (miRNA) is a kind of a small non-coding RNA functioning RNA silencing and post-transcriptional regulation of gene expression. The changes in expression of various miRNAs are reported to be associated with diseases, such as cancer, neurodegenerative diseases, and so on.
Glaucoma and retinitis pigmentosa (RP) are the leading causes of blindness in adults. Excitotoxicity caused by excess glutamate in the retinal extracellular space is thought to be one of the mechanisms of retinal ganglion cell death induced by glaucoma. RP is characterized by progressive photoreceptor-selective degeneration, and caused by mutation of the genes related to the function of photoreceptor and retinal pigment epithelium.
Recently, we demonstrated that the expression levels of some miRNAs were changed in the murine retina challenged excitotoxicity and that of a hereditary RP model animal. Retinal neurodegeneration in the NMDA-injected eye and the hereditary RP model animal could be reduced by intravitreal or subretinal injection of the molecules that modulate miRNA function, such as miRNA mimics and miRNA inhibitors. These results suggest that the development of retinal degenerative diseases could be inhibited by regulation of microRNA function.