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Abstract: TH-PO1093

Human Podocyte Modifies Energy Metabolism During Differentiation

Session Information

Category: Glomerular Diseases

  • 1204 Podocyte Biology

Authors

  • Vasquez, Jessica M., Stony Brook Medicine, Stony Brook, New York, United States
  • Mallipattu, Sandeep K., Stony Brook Medicine, Stony Brook, New York, United States
Background

Previous studies have shown increased oxidative phosphorylation (OXPHOS) with podocyte differentiation and decreased OXPHOS with hyperglycemia. Little is known about the rate of synthesis of mitochondrial proteins or how other components of metabolism, such as the TCA cycle and fatty acid oxidation, change with podocyte differentiation. The goal of this project is to identify metabolic pathways that are required for podocyte differentiation.

Methods

MTS, ATP abundance, and ATP/ADP ratios were done to ensure human podocyte viability and confirm changes in metabolism during differentiation. Oxygen consumption rate (OCR) and Extracellular Acidification Rate (ECAR) were done by SeaHorse at 3, 7, 10, and 14 days of differentiation and compared to undifferentiated cells. Immunostaining for TOMM20 was performed and quantified. SILAC was done in 12 hour pulses with heavy arginine and lysine and subsequent mitochondrial isolation was performed to determine mitochondrial protein synthesis in differentiating podocytes (with pathway enrichment analysis).

Results

We observed a stepwise increase in OXPHOS during differentiation characterized by an increase in mitochondrial biogenesis (TFAM protein quantification), network (TOMM20 staining), and increased mtDNA copy number. With differentiation, we observed an increase in total ATP but a decrease in ATP/ADP ratio. MTS assay showed no significant changes with cell differentiation. Unlabeled proteomics abundance showed the greatest increase in OXPHOS (specifically in complex 1 and 5) followed by TCA cycle. We also observed a significant decrease in mitochondrial fission proteins and an increase in mitochondrial fusion with differentiation. The most dynamic proteins with high abundance and high heavy to light (H:L) ratios during differentiation were ATP5B, NDUFS6, and OXA1l, reinforcing the importance of OXPHOS with differentiation. The most stable proteins with high abundance and low H:L ratios were involved in TCA cycle, fatty acid degradation, arginine and proline metabolism and valine, leucine and isoleucine degradation pathways (KEGG 2019 Human).

Conclusion

These data suggest that podocyte differentiation is dependent on an increase in mitochondrial biogenesis and network with a switch in metabolic programming to oxidative phosphorylation.

Funding

  • NIDDK Support