Abstract: SA-OR60
Comprehensive Characterization of Podocyte Lipotoxicity to Elucidate New Mechanisms for Podocyte-Protective Strategies
Session Information
- Glomerular Diseases: All about Podocytes
October 26, 2024 | Location: Room 1, Convention Center
Abstract Time: 05:20 PM - 05:30 PM
Category: Glomerular Diseases
- 1401 Glomerular Diseases: Mechanisms, including Podocyte Biology
Authors
- Sewerin, Sebastian, Broad Institute, Cambridge, Massachusetts, United States
- Boone, Dylan, Broad Institute, Cambridge, Massachusetts, United States
- Ross, Lindsey, Broad Institute, Cambridge, Massachusetts, United States
- Kim, Choah, Broad Institute, Cambridge, Massachusetts, United States
- Pablo, Juan Lorenzo B., Broad Institute, Cambridge, Massachusetts, United States
- Greka, Anna, Broad Institute, Cambridge, Massachusetts, United States
Background
Dyslipidemia constitutes a defining characteristic of nephrotic syndrome. Yet, its contribution to podocyte injury and how it affects their recovery potential is not well understood. Excess circulating lipids can induce a dysfunctional cell state, a phenomenon referred to as lipotoxicity. While podocyte lipotoxicity has been implicated in many diseases including diabetic kidney disease, it has only been studied in the context of a limited number of lipids. Free fatty acids (FFAs) are building blocks of many complex lipids found in human plasma and affect a wide range of cellular functions. Here, we systematically investigate the effects of a comprehensive library of >60 FFAs on podocytes using our FALCON (Fatty Acid Library for Comprehensive ONtologies) platform.
Methods
Through image-based FALCON screens, we assayed immortalized mouse podocytes for readouts such as cell morphology and viability. This allowed us to generate a functional lipotoxicity profile for podocytes which we compared to a similarly acquired profile from an immortalized human tubular epithelial cell (TEC) line. In isolated mouse glomeruli, we validated the most podocytotoxic FFA’s deleterious effects using super-resolution microscopy and investigated the associated glomerular injury pattern. To assess the mechanistic underpinnings of FFA toxicity, we screened a library of 6800 small molecules for their potential to ameliorate FFA-induced podocyte injury.
Results
Screening a wide spectrum of structurally diverse FFAs, we generated a multi-dimensional lipotoxicity profile for podocytes, revealing distinct morphological states of FFA-treated cells and functionally diverse FFA clusters. This functional profile proved distinct from that of TECs. Toxic FFA-treated isolated mouse glomeruli exhibited podocyte foot process disintegration with a focal segmental glomerular injury pattern akin to focal segmental glomerulosclerosis. Targeted experiments showed that membrane rigidification and ER stress are involved in podocyte lipotoxicity. Finally, the compound library screen provided further insights into the mechanisms of lipotoxic injury.
Conclusion
Our FALCON platform and follow-on mechanistic studies provided a comprehensive characterization of lipotoxic injury in podocytes, with potential therapeutic implications for podocytopathies.
Funding
- NIDDK Support