Abstract
Hyperglycemia impairs the retinal functions in patients with diabetic retinopathy (DR). Downregulation of long non‑coding RNA growth arrest‑specific transcript 5 (lncRNA GAS5) expression in diabetes affects glucose intake and insulin signaling. Sarcoplasmic/endoplasmic reticulum Ca2+ ATPase 2 (SERCA2) mediates the regulation of endoplasmic reticulum (ER) stress and apoptosis in high glucose (HG)‑treated podocytes. Therefore, the present study aimed to investigate the roles of lncRNA GAS5 and SERCA2 in retinal pigment epithelium cells exposed to HG. GAS5 expression levels were detected using reverse transcription‑quantitative PCR. In addition, the expression levels of SERCA2b, ER stress‑related proteins, pro‑inflammatory factors and apoptotic proteins were determined by western blot analysis, ELISA or flow cytometry. The results showed that HG treatment induced ER stress in ARPE‑19 human adult retinal pigment epithelial cells by upregulating the expression levels of phosphorylated (p)‑protein kinase R‑like ER kinase, p‑eukaryotic initiation factor 2α, activating transcription factor 4 and CCAAT/enhancer‑binding protein homologous protein. In addition, HG treatment induced apoptosis by increasing Bax, Bad and caspase 12, and by decreasing Bcl‑2 levels expression levels. Moreover, HG treatment induced inflammation by upregulating tumor necrosis factor‑α, interleukin (IL)‑1β and IL‑6 expression. However, GAS5 and SERCA2b overexpression significantly decreased ER stress‑related apoptosis and inflammation, whereas SERCA2b knockdown significantly reversed the inhibitory effect of GAS5 on ER stress, apoptosis and inflammation. The results of the present study indicated that GAS5 may suppress ER stress‑induced apoptosis and inflammation by regulating SERCA2b in HG‑treated cells. These data suggested that GAS5 may serve a vital role in the pathogenesis of DR, and it may be considered a potential target for DR therapy.