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Abstract: FR-PO330

Nogo-B Suppresses Endoplasmic Reticulum Stress in Glomerular Endothelial Cells of Diabetic Nephropathy

Session Information

Category: Diabetic Kidney Disease

  • 701 Diabetic Kidney Disease: Basic

Author

  • Zhang, Yan, Guangdong Provincial People's Hospital, Guangzhou, Guangdong, China
Background

Diadetic vascular injuries contribute to the disease progression and glomerular endothelial cells are the critical targets of injury under hyperglycemia. Nogo-B is an endoplasmic reticulum (ER)-resident protein, which plays an important role in vascular remodeling after injury. Given the location of Nogo-B in the endoplasmic reticulum in glomerular endothelial cells, we set out to investigate whether Nogo-B is involved in the ER stress of endothelial cells in diabetic nephropathy.

Methods

The level of serum and urinary Nogo-B was measured in patients with diabetic nephropathy using ELISA. The expression of Nogo-B in the ER of endothelial cells was detected by immunofluorescence co-staining with the ER marker, PDI. The expression level of ER stress related markers GRP78 was examined using WB analysis. In vitro, siRNA was used to knockdown the expression of Nogo-B in Ea.hy926 under high glucose condition and RNA-seq analysis was performed. In vivo, AAV-induced knockdown of Nogo-B was performed in db/db diabetic mice for 8 weeks. The morphology phenotypes were examined by TEM.

Results

Compared with healthy control subjects, the level of serum (fig.A) and urinary(fig.B) Nogo-B was significantly increased in DN patients. In vitro, Nogo-B was co-localized with PDI by immunofluorescent co-labeling (fig.C). The RNA-seq results demonstrated that AGE-RAGE signaling pathway was among the top 10 activated pathways by KEGG analysis (fig.D). In high glucose cultured endothelial cells, knocking down Nogo-B caused an increase in the protein level of GRP78 (fig.E). In db/db diabetic mice, knocking down Nogo-B induced glomerular endothelial cell injuries (fig.F) as demonstrated by swollen changes and karyorrhexis of the cells.

Conclusion

Nogo-B, an ER-residential protein, plays a beneficial role in glomerular endothelial cells by inactivating the ER stress. Protecting the vasculature by targeting Nogo-B may serve as a potential therapeutic strategy in the treatment of DN.

Funding

  • Government Support – Non-U.S.