Identification of O-GlcNAcylation Modification in Diabetic Retinopathy and Crosstalk with Phosphorylation of STAT3 in Retina Vascular Endothelium Cells

Abstract

Background/Aims: Recently, we observed an increase in O-GlcNAc (O-linked-ß-N-acetylglucosamine) modification, and signal transducer and activator of transcription proteins 3 (STAT3) expression in primary retinal vascular endothelial cells (RVECs) under high glucose conditions and tissues altered by diabetic retinopathy (DR). In this study, we focused on the correlations between O-GlcNAcylation and STAT3 phosphorylation, and their potential effects with regards to DR. Methods: Expression of O-GlcNAcylation and STAT3 were detected in DR-affected tissues and primary RVECs. The relationship between O-GlcNAcylation and STAT3 was further delineated by immunoprecipitation and Western blot analysis. Effects of O-GlcNAcylation on human RVEC apoptosis and involved protein expression were assayed with flow cytometry and Western blot. Results: Global O-GlcNAcylation and pSTAT3 levels were significantly elevated in diabetic rat retina and primary RVECs under high glucose conditions. In vitro assays demonstrated that the Tyr705 site was sensitive to high glucose. While O-GlcNAcylation inhibited p727STAT3 expression, augmented O-GlcNAcylation could balance p705STAT3 expression within relatively high levels corresponding to vascular endothelial growth factor (VEGF) changes. Immunoprecipitation revealed that STAT3 was modified by O-GlcNAcylation and phosphorylation simultaneously. Next, we observed that overexpression of O-GlcNAcylation could relieve human RVEC apoptosis related to the JAK2-Tyr705STAT3-VEGF pathway. Conclusion: O-GlcNAcylation could relieve RVECs apoptosis through the STAT3 pathway in DR, and O-GlcNAcylation combined with STAT3 phosphorylation might open up new insights into the mechanisms of DR and other diabetic complications.

RETRACTED ATICLE: Physcion 8-O-β-glucopyranoside exerts protective roles in high glucose-induced diabetic retinopathy via regulating lncRNA NORAD/miR-125/STAT3 signalling

“…It has been shown that STAT3 plays a leading role in tumour inflammation and immunity by regulating numerous oncogenic signalling pathways promoting pro-oncogenic inflammatory pathways, such as nuclear factor-jB and Janus kinase pathways [38]. Moreover, Xu et al demonstrated that STAT3 is up-regulated in DR-affected tissues and primary retinal vascular endothelial cells under high glucose (HG) conditions [39]. Increasing studies also showed that STAT3 could influence endothelial function in DR [40,41].…”

O-GlcNAc Transferase Regulates Angiogenesis in Idiopathic Pulmonary Arterial Hypertension

“…Glucose flux through the HBP has been linked to impaired angiogenesis and vascular dysfunction in many metabolic disorders including diabetes and cancer [30,35,58,59,65,[67][68][69][70]. However, the mechanisms have not been completely defined.…”

Functional Analysis of O-GlcNAcylation in Cancer Metastasis

“…Phosphorylation targets STAT3 residues, Tyr705 and Ser727, and these two modifications demonstrate a negative relationship to maintain its activity (78). Whereas STAT3 O-GlcNAcylation promotes Tyr705 phosphorylation, it inhibits Ser727 phosphorylation (59,60), thereby enhancing metastasis by regulating STAT3 signaling and target gene transcription.Nuclear factor erythroid 2-related factor 2 (Nrf2) is another transcription factor, the activation of which plays a critical role in sustained angiogenesis, tumor invasion and metastasis (79). For example, activated Nrf2 stabilizes BTB domain and CNC homolog 1 (BACH1), accelerating lung cancer metastasis (80).…”

“…O-GlcNAc-modified transcription factors in cancer metastasis. Some O-GlcNAc-modified metastasis related transcription factors such as HIF-1a, Notch1, NF-kB, STAT3, Nrf2 can impact cancer metastasis by affecting downstream genes (or proteins)(49)(50)(51)(52)(53)(54)(55)(56)(57)(58)(59)(60)(61).…”