Abstract: FR-PO948
Role of Sphingomyelin Phosphodiesterase Acid-Like 3B (SMPDL3b) in Fatty Acid Uptake and in Progression of Podocyte Damage
Session Information
- Glomerular Diseases: Podocyte Biology - II
November 08, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1204 Podocyte Biology
Authors
- Mallela, Shamroop Kumar, Katz Family Division of Nephrology and Hypertension,Peggy and Harold Katz Family Drug Discovery Center, Miami, Florida, United States
- Macrina, Lorenza, Katz Family Division of Nephrology and Hypertension Peggy and Harold Katz Family Drug Discovery Center, Miami, Florida, United States
- Patel, Devang M., Monash University, Mill park,, New South Wales, Australia
- Merscher, Sandra M., Katz Family Division of Nephrology and Hypertension,Peggy and Harold Katz Family Drug Discovery Center, Miami, Florida, United States
- Fornoni, Alessia, Katz Family Division of Nephrology and Hypertension,Peggy and Harold Katz Family Drug Discovery Center, Miami, Florida, United States
Background
LD play an important role in many biological processes and LD size and number have been linked to several diseases such obesity, insulin resistance and type 2 diabetes, heart disease, and non-alcoholic fatty liver disease. LD are mainly composed of triglycerides and cholesterol. We previously demonstrated that the accumulation of LDs occurs in glomeruli of experimental models of focal segmental glomerulosclerosis (FSGS) and Alport syndrome and that lipid accumulation in podocytes is one of the factors contributing to the pathogenesis of kidney disease. We furthermore demonstrated that glomerular expression of sphingomyelinase phosphodiesterase like 3b (SMPDL3b), a glycosylphosphatidylinositol (GPI) anchored protein primarily localized at plasma membrane (PM), affects the function of podocytes in FSGS and diabetic kidney disease (DKD).
With this study, we aimed at exploring a possible role of SMPDL3b in fatty acid uptake and in the formation of LDs ultimately contributing to podocyte damage.
Methods
Fatty acid uptake in podocytes was determined using the fatty acid uptake kit from Sigma (#MAK156). LDs were isolated using a kit from Cell Biolabs (#MET-5011) and proteins present in LDs were analyzed by Western blotting. Triglyceride (TAG) and esterified cholesterol (CE) content were measured using enzymatic and mass spectrometric methods. Lipolysis was measured using a lipolysis colorimetric assay kit from Sigma (#MAK211).
Results
Decreased SMPDL3b expression (siSMPDL3b) was associated with an increase in fatty acid uptake and an increased number of LDs, the number of LD was decreased in podocytes with increased SMPDL3b expression (SMPDL3b OE). Similarly, triglyceride and cholesterol ester content were increased in siSMPDL3b when compared to control podocytes. Finally, we demonstrate for the first time that SMPDL3b is present in isolated LDs suggesting a possible role for SMPDL3b in the formation of LDs.
Conclusion
Our results identify a new role of SMPDL3b in the uptake of fatty acids, the accumulation of TAG and the formation of LDs. Further experiments to understand the exact mechanism by which SMPDL3b controls the uptake of fatty acids thus contributing to podocyte damage are underway.
Funding
- Other NIH Support