Suppression of cAMP/PKA/CREB signaling ameliorates retinal injury in diabetic retinopathy

Abstract

The blood‐retinal barrier (BRB), homeostasis, neuronal integrity, and metabolic processes are all directly influenced by Müller cells, the most important retinal glial cells. We isolated primary Müller cells from Sprague–Dawley (SD) neonatal rats and treated them with glucose at varying doses. CCK‐8 was used to quantify cellular viability, and a TUNEL assay was performed to detect cell apoptosis. ELISA, immunofluorescence, and western blotting were used to assess cAMP/PKA/CREB signaling, Kir4.1, AQP4, GFAP, and VEGF levels, respectively. H&E staining was used to examine histopathological alterations in diabetic retinopathy (DR)‐affected retinal tissue in rats. As glucose concentration increases, gliosis of Müller cells became apparent, as evidenced by a decline in cell activity, an increase in apoptosis, downregulation of Kir4.1 level, and overexpression of GFAP, AQP4, and VEGF. Treatments with low, intermediate, and high glucose levels led to aberrant activation of cAMP/PKA/CREB signaling. Interestingly, blocking cAMP and PKA reduced high glucose‐induced Müller cell damage and gliosis by a significant amount. Further in vivo results suggested that cAMP or PKA inhibition significantly improved edema, bleeding, and retinal disorders. Our findings showed that high glucose exacerbated Müller cell damage and gliosis via a mechanism involving cAMP/PKA/CREB signaling.

Exploring early DNA methylation alterations in type 1 diabetes: implications of glycemic control

“…Among the genes common to the identified signaling pathways, ADCY4 , GNAS , MAPK10 , PIK3CD , and RAF1 had hypomethylated CpG sites in the promoter region and 1–5 kb upstream of the transcription start site, which may imply increase gene expression. ADCY4 ( 53 ) and GNAS ( 54 ) are both involved in the cAMP signaling pathway, which plays an important role in glucose metabolism ( 55 ), inflammation ( 41 ), and fibrosis ( 56 ), as well as in diabetic kidney disease ( 57 ), diabetic retinopathy ( 58 ), and neuropathy ( 59 ).…”