Kidney Week

Abstract: TH-PO564

Truncating PKHD1 Mutations Alter Energy Metabolism

Session Information

• Cystic Kidney Diseases - I
  November 02, 2017 | Location: Hall H, Morial Convention Center
  Abstract Time: 10:00 AM - 10:00 AM

Category: Genetic Diseases of the Kidney

• 801 Cystic Kidney Diseases

Authors

• Chumley, Phillip H., University of Alabama at Birmingham, Birmingham, Alabama, United States

Phillip H. Chumley,

• Mrug, Sylvie, University of Alabama at Birmingham, Birmingham, Alabama, United States

Sylvie Mrug,

• Zhou, Juling, University of Alabama at Birmingham, Birmingham, Alabama, United States

Juling Zhou,

• Yoder, Bradley K., University of Alabama at Birmingham, Birmingham, Alabama, United States

Bradley K. Yoder,

• Mrug, Michal, University of Alabama at Birmingham, Birmingham, Alabama, United States

Michal Mrug,

Background

Polycystin 1 deficiency triggers specific changes in energy metabolism. However, it remained uncertain whether similar changes are caused by relevant defects in other human cystoproteins. As our initial step addressing this question, we studied in vitro metabolism effects of engineered PKHD1 gene disruption along sites of truncating mutations found in patients with autosomal recessive polycystic kidney disease (ARPKD).

Methods

We prioritized PKHD1 mutations for targeting based on their reported frequency in the Aachen University Mutational Database for ARPKD. We used CRISPR/Cas9 technology to generate multiple clones of HEK293 cell lines with PKHD1 truncating mutations. Clones without mutation in this gene (WT) served as controls.

Results

PKHD1 gene mutations had no overall effect on proliferation rate estimated by MTT proliferation assay in this model, and neither did the position of the truncation. However, these mutations resulted in progressively increased extracellular media acidification. For example, when the acidity data for each of the six consecutive days (day in culture 3-8; D3-D8) were used for trajectory analyses, the trajectories of clones with PKHD1 gene mutations did not differ from WT initially on D3 (b=-0.017, p=0.2436) but had greater increase in cell culture media acidity over time (i.e., steeper increase in acidity between D3 and D8; per day: b=-0.02, p<0.0001). Likewise, specific truncating PKHD1 mutations did not differ from WT at D3 (b=-0.011 to -0.036, all p>0.2189) but each showed greater increase in acidity over time (per day: b=-0.018 to -0.029, all p<0.0001). These studies were done in aliquots of 10⁴ cells plated in six replicates from each clone; replication with 2 x 10⁴ cells yielded similar results. Our follow up analyses of the multiple clones point to several phenotypes that distinguish PKHD1 mutant from WT effects; they include changes in non-glycolytic acidification rate (1.19 vs 1.03; p=0.002), basal oxygen consumption rate (7.59 vs 5.42; p=0.015) and ATP-linked oxygen consumption rate (4.55 vs 2.98, p=0.004).

Conclusion

Together, these data suggest that defects in the major ARPKD gene are associated with abnormal energy metabolism. Future validation of these initial observations in more relevant in vivo models would point to a potential benefit of energy metabolism targeting in ARPKD.

Funding

• NIDDK Support