Kidney Week

Abstract: TH-OR045

Defective Mitochondrial Structure and Function Might Explain the Metabolic Derangement in Polycystic Kidney Disease

Session Information

• Cystic Kidney Diseases: Genes, Mechanisms, Interventions
  November 02, 2017 | Location: Room 390, Morial Convention Center
  Abstract Time: 05:18 PM - 05:30 PM

Category: Genetic Diseases of the Kidney

• 801 Cystic Kidney Diseases

Authors

• Cassina, Laura, San Raffaele Scientific Institute, Milan, Italy

Laura Cassina, PhD

• Chiaravalli, Marco, San Raffaele Scientific Institute, Milan, Italy

Marco Chiaravalli,

• Podrini, Christine, San Raffaele Scientific Institute, Milan, Italy

Christine Podrini,

• Rowe, Isaline, San Raffaele Scientific Institute, Milan, Italy

Isaline Rowe,

• Distefano, Gianfranco, San Raffaele Scientific Institute, Milan, Italy

Gianfranco Distefano,

• Boletta, Alessandra, San Raffaele Scientific Institute, Milan, Italy

Alessandra Boletta,

Group or Team Name

• Molecular basis of Polycystic Kidney Disease Unit

Background

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a common genetic disorder characterized by bilateral renal cyst formation. By metabolomic profiling, we showed that Pkd1 mutations result in enhanced glycolysis in cells and murine models of PKD. Moreover, inhibition of mitochondrial ATP synthase only mildly decreased ATP content in Pkd1^−/− cells, indicating a weak mitochondrial contribution to total ATP production (Rowe et al, Nat Med 2013). Interestingly a recent study implicated a role for the Polycystins in mitochondrial function (Padovano et al, Mol Cell Biol 2017). We are investigating the role of mitochondria in the metabolic alterations in PKD.

Methods

Mitochondrial size, shape, and structural organization were analyzed by transmission electron microscopy (TEM). Mitochondrial oxygen consumption rate (OCR) was measured using Seahorse XFe96 Analyzer, and mitochondrial network morphology by live imaging of mitochondria-targeted EYFP.

Results

TEM images of the cystic epithelia showed evidence of grossly altered mitochondrial structure in kidneys of Pkd1^flox/−:Ksp-Cre mice at P4, as compared to control littermates. We have also observed mitochondria with altered cristae and decreased matrix electron density scattered among apparently normal mitochondria. Morphometric analysis of TEM images from Pkd1^flox/−:Ksp-Cre indicated decreased mitochondrial area and length. Time course analysis of mitochondrial shaping-proteins by western blot showed that the structural alterations seem to precede the biochemical ones. In parallel, we are assessing mitochondrial morphology in Pkd1^−/− MEFs and CRISPR/Cas9-mediated Pkd1 knockout IMCD cells and preliminary findings indicate that the absence of PC-1 affects mitochondrial network morphology. In line with this, functional analysis indicated that both basal and maximal OCRs are severely affected in cells lacking Pkd1.

Conclusion

Our data indicate that alteration in mitochondrial structure might explain the severe metabolic alterations in PKD models. Alternatively, the mitochondrial structural impairment might be secondary to metabolic defects. Our investigations along with ongoing genetic interaction studies will clarify whether mitochondria are players or modifiers in the pathophysiology of ADPKD.