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Abstract: PO1713

Plin5 Deficiency in Podocyte Negatively Affects the Communication Between Lipid Droplets and Mitochondria in Alport Syndrome

Session Information

Category: Glomerular Diseases

  • 1204 Podocyte Biology

Authors

  • Kim, Jin Ju, University of Miami School of Medicine, Miami, Florida, United States
  • Wilbon, Sydney S., The University of Texas Health Science Center at Houston John P and Katherine G McGovern Medical School, Houston, Texas, United States
  • Molina David, Judith T., University of Miami School of Medicine, Miami, Florida, United States
  • Szeto, Hazel H., Social Profit Network, Melno Park, California, United States
  • Miner, Jeffrey H., Washington University in St Louis, St Louis, Missouri, United States
  • Fontanesi, Flavia, University of Miami School of Medicine, Miami, Florida, United States
  • Merscher, Sandra M., University of Miami School of Medicine, Miami, Florida, United States
  • Fornoni, Alessia, University of Miami School of Medicine, Miami, Florida, United States
Background

Alport Syndrome (AS) is a hereditary disease caused by mutations in collagen type IV. We and others have demonstrated pathogenic renal lipid droplets (LD) and triglyceride (TG) accumulation in experimental AS (Col4a3KO mice). Excessive FFA catabolism resulting from excessive lipolysis of TG is a major contributor to cell lipotoxicity. Perilipin 5 (PLIN5) is an LD-related protein that plays a critical role in regulating TG lipase activity and the interactions between LD and mitochondria, where it protects mitochondria from excessive exposure to FFA. Here we test the hypothesis that PLIN5 is expressed in podocytes and that PLIN5 deficiency in AS causes excessive TG breakdown and the loss of LD-mitochondrial contact, thus contributing to kidney failure.

Methods

In vitro, Immortalized AS podocytes and WT podocytes were established and characterized in our laboratory by breeding the Col4a3KO mice (Jackson Laboratory) to H-2kb-tsA58 transgenic mice (Charles River). PLIN5 expression was determined by RT-PCR and western blot analysis in AS podocytes and kidney cortex in AS mice when compared to controls. TG lipolysis and FFA quantification were determined and normalized to protein content. LD-Mitochondrial contact was determined by TEM analysis.

Results

PLIN5 deficiency was observed in the kidney cortex of Col4a3KO mice when compared to controls (p<0.001). We demonstrate that PLIN5 is expressed in podocytes, and the expression of PLIN5 is significantly decreased in AS podocytes compared to WT podocytes (p<0.01). AS podocytes also showed significantly increased rates of TG lipolysis (p<0.05), intracellular free fatty acids (p<0.05) and apoptosis (p<0.01) when compared to WT podocytes. AS podocytes had reduced number of LD-mitochondrial contacts (P<0.05), implying that and apoptosis. Moreover, Ezetimibe, which restored LD-Mitochondrial contact in vitro (P<0.05) and improved kidney function in vivo, was found to restore PLIN5 expression in vitro and in vivo (P<0.05).

Conclusion

Our study suggests that podocyte PLIN5 deficiency may cause podocyte injury in AS through excessive TG lipolysis and inefficient FA transfer from LD to Mitochondria, leading to mitochondrial dysfunction and contributing to disease progression.