Abstract: TH-PO600

A Systems Biology Approach Identifies Reciprocal Changes in mir-193b-3p and PIK3R1 as Drivers of Cyst Growth in ADPKD

Session Information

Category: Genetic Diseases of the Kidney

  • 801 Cystic Kidney Diseases

Authors

  • Vergoz, Laura, University of Sheffield, Sheffield, United Kingdom
  • Streets, Andrew J., University of Sheffield, Sheffield, United Kingdom
  • Malas, Tareq B, Leiden University Medical Center, Leiden, Netherlands
  • Lannoy, Morgane, University of Sheffield, Sheffield, United Kingdom
  • 't Hoen, Peter A, Leiden University Medical Center, Leiden, Netherlands
  • Peters, Dorien J.M., Leiden University Medical Center, Leiden, Netherlands
  • Ong, Albert C., University of Sheffield, Sheffield, United Kingdom
Background

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited cause of end-stage renal disease worldwide. PKD1 and PKD2 mutations are present in most patients with clear genotype-phenotype correlations. However, the intra-familial phenotypic variability in some pedigrees suggests the influence of non-allelic factors. Non-coding RNAs e.g. microRNAs are known to play a major role in health and disease (including PKD) via control of mRNA stability or translation. We recently conducted a parallel mRNA/miRNA array study which found mir-193b-3p, among others, downregulated in human ADPKD cells (Streets et al, 2017), associated with dysregulation of the ErbB4/EGF pathway.

Methods

To select other relevant genes regulated by mir-193b-3p, we compared our human mRNA dataset with mRNA expression data from Pkd1 mutant mice (Malas et al, 2017). Dual-reporter luciferase assays with native and mutant seed sequences and immunoblotting were used to demonstrate functional binding of mir-193b-3p to the 3’UTR of PIK3R1 mRNA. IGF-1 stimulation of human ADPKD cystic cells in 2D and 3D cultures characterized the role of PIK3R1 in Akt or ERK signaling and on cyst growth.

Results

PIK3R1 was selected as a strong candidate gene and shown to be upregulated ~3-fold in human cells and mouse Pkd1 kidney tissue. In parallel, the catalytic subunit PIK3CA was also overexpressed suggesting the most common PI3K enzyme combination is upregulated in ADPKD cells. A functional interaction between PIK3R1 and mir-193b-3p was confirmed by luciferase assays and immunoblotting. Knockdown of PIK3R1 or PI3K chemical inhibitors significantly reduced cyst growth in ADPKD cells and influenced Akt and ERK activation by IGF-1.

Conclusion

We report that PIK3R1 and one of its catalytic subunits are upregulated in ADPKD and confirm that it is a target for mir-193b-3p. The role of PIK3R1/PIK3CA in driving cyst growth in ADPKD was functionally linked to hyperactivation of Akt and ERK. Co-regulation of PIK3R1 and ErbB4 by mir-193b-3p supports the development of PI3K and ErbB4 inhibitors or mir-193b-3p activators for the treatment of ADPKD.

Funding

  • Government Support - Non-U.S.