Altered retinal microRNA expression profile in a mouse model of retinitis pigmentosa

Background: The role played by microRNAs (miRs) as common regulators in physiologic processes such as development and various disease states was recently highlighted. Retinitis pigmentosa (RP) linked to RHO (which encodes rhodopsin) is the most frequent form of inherited retinal degeneration that leads to blindness, for which there are no current therapies. Little is known about the cellular mechanisms that connect mutations within RHO to eventual photoreceptor cell death by apoptosis. Results: Global miR expression profiling using miR microarray technology and quantitative realtime RT-PCR (qPCR) was performed in mouse retinas. RNA samples from retina of a mouse model of RP carrying a mutant Pro347Ser RHO transgene and from wild-type retina, brain and a wholebody representation (prepared by pooling total RNA from eight different mouse organs) exhibited notably different miR profiles. Expression of retina-specific and recently described retinal miRs was semi-quantitatively demonstrated in wild-type mouse retina. Alterations greater than twofold were found in the expression of nine miRs in Pro347Ser as compared with wild-type retina (P < 0.05). Expression of miR-1 and miR-133 decreased by more than 2.5-fold (P < 0.001), whereas expression of miR-96 and miR-183 increased by more than 3-fold (P < 0.001) in Pro347Ser retinas, as validated by qPCR. Potential retinal targets for these miRs were predicted in silico. Conclusion: This is the first miR microarray study to focus on evaluating altered miR expression in retinal disease. Additionally, novel retinal preference for miR-376a and miR-691 was identified. The results obtained contribute toward elucidating the function of miRs in normal and diseased retina. Modulation of expression of retinal miRs may represent a future therapeutic strategy for retinopathies such as RP.