Suppression of cAMP/PKA/CREB signaling ameliorates retinal injury in diabetic retinopathy
Xiao-Ling Fang1,2, Qin Zhang3, Wen-Wen Xue1,2
1Department of Ophthalmology, Shanghai Eye Diseases Prevention and Treatment Center, Shanghai Eye Hospital, Shanghai, China.
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.
Insights
High glucose damages Müller cells in the retina, increasing gliosis and apoptosis via cAMP/PKA/CREB signaling. Inhibiting these pathways protects against diabetic retinopathy complications.
Area of Science:
- Ophthalmology
- Neuroscience
- Cell Biology
Background:
- Müller cells are crucial retinal glial cells regulating blood-retinal barrier, homeostasis, and neuronal integrity.
- Dysfunction of Müller cells is implicated in various retinal pathologies, including diabetic retinopathy.
Purpose of the Study:
- To investigate the impact of high glucose on Müller cell function and viability.
- To elucidate the role of cAMP/PKA/CREB signaling in high glucose-induced Müller cell damage and gliosis.
- To evaluate the therapeutic potential of inhibiting cAMP/PKA signaling in diabetic retinopathy.
Main Methods:
- Primary Müller cells isolated from Sprague-Dawley rats were treated with varying glucose concentrations.
- Cell viability assessed by CCK-8 assay; apoptosis detected by TUNEL assay.
- ELISA, immunofluorescence, and western blotting used to analyze signaling pathways and protein expression (Kir4.1, AQP4, GFAP, VEGF).
- Histopathological analysis of diabetic retinopathy rat retinas using H&E staining.
Main Results:
- Increased glucose concentration led to Müller cell gliosis, decreased viability, increased apoptosis, and altered expression of Kir4.1, GFAP, AQP4, and VEGF.
- High glucose aberrantly activated the cAMP/PKA/CREB signaling pathway.
- Inhibition of cAMP and PKA significantly reduced high glucose-induced Müller cell damage and gliosis.
- In vivo, cAMP or PKA inhibition ameliorated diabetic retinopathy symptoms like edema and bleeding.
Conclusions:
- High glucose exacerbates Müller cell damage and gliosis through the cAMP/PKA/CREB signaling pathway.
- Targeting cAMP/PKA signaling offers a potential therapeutic strategy for managing diabetic retinopathy.
