Objective: The catabolic process of autophagy is arousing the attention of researchers studying diabetic retinopathy (DR), but the role and molecular mechanism of autophagy in DR are still unclear.
Methods: An in vivo diabetic rat model and in vitro hyperglycemic-exposed retinal pigment epithelium (RPE) cell cultures were established to mimic early DR. Transmission electron microscopy and mRFP-GFP-LC3 adenovirus transfection were applied for autophagic flux analysis. MicroRNA (miR)-19a-3p, members of the phosphate and tensin homolog (PTEN)/Akt/mammalian target of rapamycin (mTOR) pathway, and the autophagy-related proteins light chain (LC)3II/I and p62 were detected. Annexin V, transwell, Cell Counting Kit-8, fluorescein isothiocyanate-dextran monolayer permeability assay, and transepithelial electrical resistance were performed to evaluate the effects of regulating autophagy on RPE cells under the DR condition.
Results: Autophagy was aberrantly activated in DR as evidenced by autophagosome accumulation. Further mechanistic experiments revealed that DR induced PTEN expression, thus inhibiting Akt/mTOR phosphorylation and stimulating aberrant autophagy and apoptosis. Notably, these events could be reversed by miR-19a-3p directly targeting PTEN. Downregulation of autophagy by miR-19a-3p overexpression, PTEN knockdown, or 3-methyladenine (3-MA) treatment inhibited autophagosome formation and thus effectively ameliorated hyperglycemia-induced RPE cell apoptosis, increased migration, inhibited viability, and enhanced monolayer permeability under the DR condition.
Conclusions: Our findings suggest that upregulation of miR-19a-3p inhibits aberrant autophagy by directly targeting PTEN, thus protecting RPE cells against DR damage. miR-19a-3p may represent a novel therapeutic target for inducing protective autophagy in early DR.
Keywords: Autophagy; Hyperglycemia; PTEN; Retinal pigment epithelium cell; microRNA.
Copyright © 2023. Published by Elsevier B.V.