7,8-Dihydroxyflavone ameliorates high-glucose induced diabetic apoptosis in human retinal pigment epithelial cells by activating TrkB

Background: In diabetic retinopathy, prolonged high-level blood glucose induced significant impairments among various retinal tissues, including retinal pigment epithelial (RPE) cells. In an in vitro model of human RPE cells, we evaluated whether 7,8-Dihydroxyflavone (DHF) may effectively prevent high glucose-induced diabetic apoptosis among human RPE cells. Method: ARPE-19 cells, a Human RPE cell line, were treated with D-glucose (50 mM) to induce apoptosis in vitro. Prior to glucose, ARPE-19 cells were pre-incubated with various concentrations of DHF. The effect of DHF on D.-glucose-induced apoptosis was examined by TUNEL assay, in a concentration-dependent manner. The biological effects of DHF on Caspase-9 (Casp-9) and TrkB signaling pathways in D-glucose-injured ARPE-19 cells were evaluated by qRT-PCR and western blot (WB) assays. A TrkB antagonist, K252a, was also applied in DHF and D-glucose treated ARPE-19 cells. Possible effect of K252a blocking TrkB signaling pathway, thus reversing DHF-modulated apoptosis prevention was also examined by TUNEL and WB assays. Results: DHF ameliorated D-glucose-induced diabetic apoptosis in ARPE-19 cells. Apoptotic factor Casp-9, at both mRNA and protein levels, were drastically inhibited by DHF in D-glucose-injured ARPE-19 cells. Also, DHF activated TrkB signaling pathway through phosphorylation. K252a dramatically reversed the preventive effect of DHF on D-glucose-induced apoptosis in ARPE-19 cells. Further investigation showed that K252a functioned through de-activating or de-phosphorylating TrkB signaling pathway. Conclusion: This work demonstrates that DHF, through activation of TrkB signaling pathway, has a preventive function in D-glucose-induced apoptosis in PRE cells in diabetic retinopathy. (C) 2017 Published by Elsevier Inc.