MicroRNA profile comparison of the corneal endothelia of young and old mice: implications for senescence of the corneal endothelium

PURPOSE To identify critical microRNAs (miRNAs) that play important roles in regulating the aging of corneal endothelial cells in mice aged 10-13 weeks and 2 years. METHODS We collected the corneal endothelia from 30 mice aged 10-13 weeks and 30 mice aged 2 years. The samples were pooled into six groups (Y1, Y2, Y3 and S1, S2, S3). Each group comprised corneal endothelia from 10 mice, and these six groups were used for a genome-wide miRNA microarray study. The expression levels of eight selected miRNAs were further validated independently by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Target genes were predicted using a computational approach due to their base-pairing rules between miRNA and messenger RNA target sites. The locations of binding sequences were within the target's 3' untranslated regions (UTR), and the conservation of target binding sequences occurred within related genomes. Additional gene ontology and signaling pathway analyses were performed using bioinformatics tools. RESULTS Twenty-seven miRNAs (7 upregulated and 20 downregulated) were found to be differentially expressed (fold change >2, p value <0.05) in the corneal endothelia of adult and old mice. The qRT-PCR results confirmed the differential expression of eight miRNAs between the corneal endothelia of adult and old mice. A computational approach demonstrated that the target genes of the differentially expressed miRNAs might be involved in several signaling pathways, including the glutamatergic synapse pathway (p=0.000313), the phosphatidylinositol signaling pathway (p=0.00197), the neurotrophin signaling pathway (p=0.00687), the transforming growth factor-beta signaling pathway (p=0.0143), and oxidative phosphorylation (p=0.0223). CONCLUSIONS Our study identified miRNAs that are differentially expressed in the corneal endothelium during aging for the first time. We also identified fluctuations in the expression of these specific miRNAs that may be related to age-specific changes. Understanding miRNA expression and interactions in tissues such as the cornea may aid in the understanding of the basic and pathophysiological processes of age-related ocular pathologies.