MicroRNA-26a-5p inhibits high glucose-induced Müller cells apoptosis by mediating PTEN/PI3K/Akt pathway

To investigate the functions of microRNA-26a-5p (miR-26a-5p) in the high glucose (HG)-induced rat retinal Müller cells (rMC-1) apoptosis and its possible mechanism.

rMC-1 cells were transfected with miR-26a-5p mimics or phosphatase and tensin homolog (PTEN) siRNA under HG conditions. Cell apoptosis was analyzed by propidium iodide (PI) and annexin Ⅴ fluorescein isothiocyanate (FITC) staining. PTEN/phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway activation was assessed by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot. Inflammatory cytokines, interleukin (IL)-1β, IL-6, were measured by enzyme-linked immunosorbent assay (ELISA). The miR-26a-5p-PTEN interaction was validated by dual-luciferase assay.

HG significantly suppressed miR-26a-5p expression and induced apoptosis in rMC-1 cells. Overexpression of miR-26a-5p attenuated HG-induced apoptosis by directly targeting PTEN, as confirmed by dual-luciferase reporter assay, which demonstrated that miR-26a-5p directly binds to the PTEN 3’-UTR, resulting in a 50% reduction in luciferase activity (P<0.01). Consistent with this, miR-26a-5p overexpression downregulated PTEN expression, enhanced PI3K/Akt phosphorylation, and suppressed the secretion of IL-1β and IL-6 (all P<0.01).

Upregulation of miR-26a-5p protects rMC-1 from HG-induced apoptosis by targeting PTEN via regulating the PI3K/Akt pathway and inflammatory responses. miR-26a-5p may be a potential therapeutic target for diabetic retinal neurodegeneration.