The glucocorticoid receptor as a master regulator of Müller cell gliosis in the diabetic retina

Diabetic retinopathy (DR) is considered a primarily microvascular complication of diabetes. Müller glia cells are at the center of the retinal neurovascular unit and play a critical role in DR. We therefore investigated Müller cell-specific signaling pathways that are altered in DR to identify novel targets for gene therapy. Using a multi-omics approach on purified Müller cells from diabetic db/db mice, we found the mRNA and protein expression of the glucocorticoid receptor (GR) to be significantly decreased, while its target gene cluster was down-regulated. Further, oPOSSUM TF analysis and ATAC-sequencing identified the GR as a master regulator of Müller cell gliosis in DR. Cortisol not only increased GR phosphorylation. It also induced changes in the expression of known GR target genes in retinal explants. Finally, retinal functionality was improved by AAV-mediated overexpression of GR in Müller cells. Our study demonstrates an important role of the glial GR in DR and implies that therapeutic approaches targeting this signalling pathway should be aimed at increasing GR expression rather than the addition of more ligand. ![Figure][1] ### Competing Interest Statement The authors have declared no competing interest. * AAV : Adeno-associated virus ATAC-seq : Assay for transposase-accessible chromatin using sequencing DR Diabetic retinopathy EGFP : Enhanced green fluorescent protein ELISA Enzyme-linked immunosorbent assay ERG Electroretinogram GCL : Ganglion cell layer GFAP : Glial fibrillary acidic protein GR : Glucocorticoid receptor INL : Inner nuclear layer IPL : Inner plexiform layer MACS : Magnetic activated cell sorting ONL Outer nuclear layer OPL : Outer plexiform layer OXPHOS Oxidative phosphorylation PBS Phosphate-buffered saline qPCR : Quantitative realtime polymerase chain reaction TGFβ Tumor growth factor β VEGF : Vascular endothelial growth factor [1]: pending:yes