Kidney Week

Abstract: FR-PO293

Loss of Globotriaosylceramide Protects against Diabetic Kidney Disease

Session Information

• Diabetic Kidney Disease: Basic - 1
  October 25, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Diabetic Kidney Disease

• 701 Diabetic Kidney Disease: Basic

Authors

• Ramakrishnan, Suresh K, UniversitatsKlinikum Heidelberg, Heidelberg, Baden-Württemberg, Germany

Suresh K Ramakrishnan, PhD

• Naik, Shruti, UniversitatsKlinikum Heidelberg, Heidelberg, Baden-Württemberg, Germany

Shruti Naik, MSc

• Dibra, Indira, UniversitatsKlinikum Heidelberg, Heidelberg, Baden-Württemberg, Germany

Indira Dibra, MSc

• Rickert-Zacharias, Verena, UniversitatsKlinikum Heidelberg, Heidelberg, Baden-Württemberg, Germany

Verena Rickert-Zacharias, PhD, ScM

• Sandhoff, Roger, Deutsches Krebsforschungszentrum, Heidelberg, Baden-Württemberg, Germany

Roger Sandhoff

• Groene, Hermann-Josef, Philipps-Universitat Marburg, Marburg, Hessen, Germany

Hermann-Josef Groene, MD

• Simons, Matias, UniversitatsKlinikum Heidelberg, Heidelberg, Baden-Württemberg, Germany

Matias Simons, MD

Background

Globotriaosylceramide (Gb3) is a glycosphingolipid that is formed by the addition of a galactose molecule to lactosylceramide by Gb3 synthase (Gb3S). In acute kidney injury models, Gb3 knockout has shown a protective effect on proximal tubular cells (PTCs). This can be attributed to loss of Gb3 contributing to reduced uptake of potentially damaging excess filtrates, such as albumin, lipids and toxins by PTCs. Here, we aimed to study the therapeutic potential of Gb3 inhibition in a mouse model for diabetic kidney disease (DKD).

Methods

8 week-old Gb3S wildtype (WT) and knockout (KO) mice were injected with streptozotocin (STZ-50mg/ml) consecutively for 5 days. A high fat diet enriched with saturated fatty acids (SFA) was given from 11 weeks until 24 weeks of age. These STZ-SFA mice were described by us to exhibit DKD features (Perez-Marti et al, 2022). Transdermal GFR, urinary parameters, kidney injury and fibrosis markers (qPCR) were measured at the end point of the experiments. Histopathological analysis of kidney sections was performed. Oil red O-staining was used to check for lipid droplets. Western blotting was performed to quantify kidney and lipid markers protein expression.Drosophila nephrocytes were used to study lipid droplets upon knockdown of α4GT1, fly ortholog of Gb3S, using UAS-GAL4 system. Bodipy (493/503) staining was used to visualize lipid droplets (Confocal microscopy).

Results

Compared to STZ-SFA WT mice the STZ-SFA KO mice have normal GFR. Also, they display significantly decreased expression of kidney injury and fibrosis markers as well as lower albuminuria and glucosuria. Interestingly, we observed depletion of lipid droplet accumulation in the S2 and S3 proximal tubular segments of STZ-SFA KO mice compared to STZ-SFA WT mice. Protein expression of Perilipin-2 which coats lipid droplets was downregulated in the STZ-SFA KO kidney samples compared to STZ-SFA WT samples. Furthermore, α4GT1 knockdown nephrocytes lacked lipid droplets, suggesting a cell-autonomous effect of Gb3S deficiency on lipid droplets.

Conclusion

Our data suggest that loss of Gb3 is beneficial in alleviating kidney damage in the STZ-SFA mouse model. We speculate that decreased lipid uptake and lower lipid droplet accumulation in the proximal tubules may be one of the possible reasons for the beneficial effects.