GnT-V-mediated aberrant N-glycosylation of TIMP-1 promotes diabetic retinopathy progression.

BACKGROUND: Vascular endothelial growth factor (VEGF) signaling pathway plays an important role in the progression of diabetic retinopathy (DR). The glycosylation modification process of many key functional proteins in DR patients is abnormal. However, the potential involvement of abnormal N-glycoproteins in DR progression remains unclear. METHODS: Glycoproteomic profiling of the vitreous humor was performed. The level of protein and N-glycoprotein was confirmed by Western blot and Lectin blot, respectively. The cell viability and migration efficiency were detected by CCK-8 and Transwell assay. Flow cytometry was conducted to analyze the level of cell apoptosis and reactive oxygen specie. Malondialdehyde, superoxide dismutase activity and VEGF content were detected by Enzyme linked immunosorbent assays. The interaction of metalloproteinase 1 (TIMP-1) with N-acetylglucosamine transferase V (GnT-V) was detected by GST pull-down. Hematoxylin and eosin staining and choroidal and retinal flat mount stained with fluorescein isothiocyanate-Dextran assay were used for functional research in vivo. RESULTS: We found that N-glycosylation was up-regulated in DR rats and high glucose (HG)-induced human retinal pigment epithelium cell line ARPE-19. HG-induced inhibited the viability of ARPE-19 cells and promoted cell apoptosis and oxidative stress (OS), but these effects were reversed with kifunensine treatment, GnT-V knockdown and TIMP-1 mutation. Additionally, GnT-V binds to TIMP-1 to promote N-glycosylation of TIMP-1. Over-expression of GnT-V inhibited the viability of ARPE-19 cells and promoted cell apoptosis, OS and VEGF release, which these effects were reversed with TIMP-1 mutation. Interestingly, over-expression of GnT-V promoted retinal microvascular endothelial cells (RMECs) angiogenesis but was revered with TIMP-1 mutation, which was terminally boosted by VEGF-A treatment. Finally, knockdown of GnT-V relieved DR progression. CONCLUSION: The findings indicate that GnT-V can promote RMECs angiogenesis and ARPE-19 cells injury through activation VEGF signaling pathway by increasing TIMP-1 N-glycosylation level, which provides a new theoretical basis for the prevention of DR.

Prostaglandin E2 promotes Th17 differentiation induces corneal epithelial cell apoptosis and participates in the progression of dry eye.

This study is mainly based on T helper type 17 (Th17) cells analysis of the mechanism of prostaglandin E2 (PGE2) promoting the progression of dry eye (DE). Scopolamine and dry environment were used to induce mice DE model. Celecoxib was used to inhibit PGE2. Corneal epithelial cells and CD4+ T cells were used to construct a co-culture system. The osmotic pressure was increased by adding NaCl to simulate DE in vitro. AH6809 and E7046 were used to pre-culture to inhibit EP2/4 in T cells to verify the effect of exogenous PGE2 on Th17 cell differentiation and corneal epithelial cell apoptosis. The function of Th17 cells was analyzed by detecting RORγt and interleukin-17 (IL-17). PGE2 was instilled on the ocular surface to induce DE symptoms of mice. AH6809 and E7046 were used to inhibit EP2/4. The corneal epithelial cell apoptosis was observed by TUNEL. The proportion of Th17 cells in corneal tissue and draining lymph nodes (DLNs) was detected by flow cytometry. In DE mice, the concentration of PGE2 and IL-17 increased in tears, and the proportion of Th17 increased, while inhibition of PGE2 alleviated the symptoms of DE and inhibited Th17 differentiation. Hypertonic environment induces corneal epithelial cells to secrete PGE2. PGE2 promoted the expression of EP2/4 and the differentiation of Th17 cells in vitro. The hypertonic environment promoted PGE2 level and the apoptosis of corneal epithelial cells in the co-culture system. PGE2 alone did not cause corneal epithelial cell apoptosis, while PGE2 promoted apoptosis by promoting Th17. Blocking EP2/4 reduced the induction of Th17 differentiation by PGE2 and the promoted corneal epithelial cell apoptosis. Animal experiments showed that exogenous PGE2 induced DE symptoms. Blocking EP2/4 not only inhibited the proportion of Th17, but also alleviated the apoptosis of corneal epithelial cells caused by PGE2. PGE2 induces aggravation of inflammation by promoting the level of Th17 in the ocular surface, and causes corneal epithelial cell apoptosis, thereby participating in the progression of DE.

The mechanism by which crocetin regulates the lncRNA NEAT1/miR-125b-5p/SOX7 molecular axis to inhibit high glucose-induced diabetic retinopathy.

Diabetic retinopathy (DR) is a high-incidence microvascular complication with retinal neovascularization that generates irreversible visual impairment. However, the mechanism of DR is unclear and needs to be further explored. To explore the the effects of crocetin on expression of NEAT1 and miR-125b-5p and the proliferation activity, migration ability, and angiogenesis ability of human retinal microvascular endothelial cells (hRMECs), RT-qPCR, CCK-8, Transwell, and tube formation assays were performed. Additionally, Western blot was used to detect the expression of SOX7, VEGFA and CD31. Furthermore, a dual-luciferase reporter gene was used to verify the targeting connection. The DR mouse model was constructed by STZ. The effect of crocetin on DR angiogenesis was detected by hematoxylin-eosin (HE) staining, immunohistochemistry (IHC), retinal digest preparations and Western blot. The results showed that crocetin inhibited the high-glucose (Hg)-induced upregulation of NEAT1 and SOX7 and the downregulation of miR-125b-5p. Crocetin inhibited Hg-induced proliferation, migration and angiogenesis by upregulating the targeted inhibition of SOX7 by miR-125b-5p through the inhibition of NEAT1. To summarize, our study revealed that crocetin has a protective effect on Hg-induced DR by regulating the lncRNA NEAT1/miR-125b-5p/SOX7 molecular axis.