MiR-340/iASPP axis affects UVB-mediated retinal pigment epithelium (RPE) cell damage

Long-term exposure to ultraviolet B (UVB) light increases the risk of UVB damage due to increased UVB absorption by the retina and may further lead to age-related eye diseases. The retinal pigment epithelium (RPE) cell is a main target of UVB reaching the retina; its degeneration is an essential event in UVB-mediated age-related macular degeneration (AMD). Herein, we first evaluated the expression and effect of iASPP, an inhibitory regulator of apoptosis, in UVB-induced RPE cell damage. Through the mechanism of RNA interference at the post-transcriptional level, miRNA affects a variety of cellular processes, including UVB-mediated cell damage. We next screened for upstream candidate miRNAs that may regulate iASPP expression. Among 8 candidate miRNAs, UVB significantly increased miR-340 levels. We also confirmed the direct binding of miR-340 to the 3′UTR of iASPP, and assessed the combined effect of miR-340 and iASPP on UVB-induced RPE cell damage. Taken together, we demonstrated the possible mechanisms involved in UVB-induced retinal damage. In RPE cells, UVB irradiation inhibits iASPP expression through inducing miR-340 expression, thereby promoting RPE cell apoptosis and suppressing cell viability via affecting p53, p21 and caspase-3 protein expression. Targeting miR-340 to rescue iASPP expression in RPE cells may help treat UVB-mediated retinal damage.