Kidney Week

Abstract: SA-PO482

Investigating the Role of Peroxisomal Metabolism in Polycystic Kidney Disease

Session Information

• Cystic Kidney Diseases: Basic/Translational
  November 09, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Genetic Diseases of the Kidneys

• 1001 Genetic Diseases of the Kidneys: Cystic

Authors

• Terabayashi, Takeshi, National Intitutes of Health, Bethesda, Maryland, United States

Takeshi Terabayashi,

• Menezes, Luis F., National Intitutes of Health, Bethesda, Maryland, United States

Luis F. Menezes,

• Zhou, Fang, National Intitutes of Health, Bethesda, Maryland, United States

Fang Zhou,

• Germino, Gregory G., National Intitutes of Health, Bethesda, Maryland, United States

Gregory G. Germino,

Background

Our group recently reported impaired fatty acid oxidation and abnormal mitochondria in Pkd1 mutants. However, how these phenomena contribute to cystogenesis in ADPKD is unclear. Peroxisomes interact with mitochondria physically and functionally, and congenital peroxisome biogenesis disorders cause developmental/metabolic phenotypes including renal cysts and aberrant mitochondria. Given the features observed in both PKD and the peroxisome diseases, we hypothesized PKD1 might affect peroxisomal activity thus may alter mitochondrial behavior.

Methods

Peroxisome biogenesis in control and Pkd1-/- kidney epithelial cells was studied by evaluating the abundance of peroxisomes using staining of PMP70 and the peroxisome matrix import was assayed using GFP-SKL. We also investigated whether a tagged PC1 C-terminus (CTT) that localizes to mitochondria also co-localizes with peroxisome markers using live cell imaging. In addition, peroxisome-specific β-oxidation in control and Pkd1-/- cells was studied by mass spectrometry (MS) using deuterium-labeled behenic acid. Lastly, comprehensive analyzes of long-chain/very long-chain fatty acids were performed by MS of cystic kidneys of Pkd1^fl/fl; Ksp-Cre mice.

Results

There was no significant difference in peroxisomal abundance in control and Pkd1 -/- cells [peroxisome number per cell: 96784LTL WT 49.0±13.2 vs MUT 43.0±18.1 (p=0.4), 121112LTL WT 30.4±9.0 vs MUT 25.9±3.8 (p=0.2)]. GFP-SKL was equally well-recruited into peroxisomes in WT and MUT cells, suggesting peroxisome biogenesis is not defective. Exogenously expressed PC1 CTT exclusively localized to mitochondria. In the labeled behenic study, peroxisome β-oxidation was not significantlly different in Pkd1-/- cells (n=3 each cell line pair (each with 3–5 replicates), 89.6±6.7 vs 84.2±7.6%, p=0.3). In the kidney tissues, total levels of fatty acids (C10–C24) were lower in Pkd1 mutant mice (control n=23, MUT n=12, 104.6±7.7 vs 83.9±7.1 μg/mg, p<6.3e^-9), while the ratio of C24:0/C22:0, used as a readout of peroxisome disorder was not changed in the mutant mice (0.56±0.11 vs 0.58±0.11, p=0.5).

Conclusion

These data suggest that peroxisome dysfunction is not responsible for the fatty acid oxidation defect previously described in Pkd1 mutant cells. On the other hand, further study will be required to figure out the role of the observed reduction of fatty acids levels in vivo.

Funding

• NIDDK Support