Decreased miR-187 induces retinal ganglion cell apoptosis through upregulating SMAD7 in glaucoma

Retinal ganglion cells (RGCs) are commonly experienced optic nerve diseases including glaucoma-induced injury that results in decrease of cell survival. However, the underlying mechanism remains to be elaborated. This present study was to focus on the miR-187 and Transforming growth factor-β (TGF-β) signal and investigated their roles in RGCs apoptosis and proliferation.

RGC-5 retinal ganglion cell line was chose in present study and subjected to miR-187 mimic or inhibitor transfection. Cell apoptosis was evaluated using flow cytometry-based Annexin V-PI assay. Cell proliferation was examined using CCK-8. Protein levels of Smad2/3/7 were determined using western blotting.

miR-187 negatively regulated cell survival via inhibiting cell apoptosis and promoting cell proliferation. We observed that alteration expression of miR-187 is closely related to phosphorylation levels of Smad2 and Smad3. This correlation is associated with down-regulation of Smad7 induced by miR-187 via targeting Smad7 3'-UTR. From result of co-transfection of Smad7-plasmid and miR-187 mimic or siSmad7 and miR-187 inhibitor, we concluded that cell proliferation and apoptosis was mediated by miR-187/Smad7 axis.

In summary, cell internal signal transduction, miR-187 regulating Smad7 expression, plays a vital role in retinal ganglion cell survival.