The Role of miRNAs in Retinal Physiology and in Inherited Retinal Disorders.

MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression at the posttranscriptional level. Several studies have highlighted their role as key regulators of different physiological processes that underly retinal homeostasis. Recent evidence suggests that they play a role not only at the intracellular level but also extracellularly, participating in cell-cell cross talk by being transported via extracellular vesicles (EVs). Moreover, changes in miRNA expression levels have been associated with different forms of retinal diseases, such as inherited retinal diseases (IRDs). IRDs are a group of genetic disorders characterized by photoreceptor cell death and retinal degeneration. Notably, miRNAs can simultaneously regulate multiple molecular pathways associated with disease initiation and progression. Finally, modulation of miRNAs through upregulation or downregulation has shown beneficial effects in different IRD mouse models. Here, we provide a comprehensive overview of retinal miRNA expression profiles in both healthy and IRD conditions and explore their potential as therapeutic targets for clinical applications.