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Kidney Week

Abstract: TH-PO697

Long Noncoding RNA Hoxb3os Is Dysregulated in Autosomal Dominant Polycystic Kidney Disease and Regulates mTOR Signaling In Vivo

Session Information

Category: Genetic Diseases of the Kidney

  • 1001 Genetic Diseases of the Kidney: Cystic

Authors

  • Aboudehen, Karam S., University of Minnesota, Minneapolis, Minnesota, United States
  • Farahani, Shayan A., University of Minnesota, Minneapolis, Minnesota, United States
  • Kanchwala, Mohammed Shabbir, University of Texas Southwestern Medical Center, Dallas, Texas, United States
  • Chan, Siu Chiu, University of Minnesota, Minneapolis, Minnesota, United States
  • Avdulov, Svetlana, University of Minnesota, Minneapolis, Minnesota, United States
  • Mickelson, Alan, University of Minnesota, Minneapolis, Minnesota, United States
  • Lee, Dayeon, University of Minnesota, Minneapolis, Minnesota, United States
  • Gearhart, Micah D., University of Minnesota, Minneapolis, Minnesota, United States
  • Patel, Vishal, University of Texas Southwestern Medical Center, Dallas, Texas, United States
  • Xing, Chao, University of Texas Southwestern Medical Center, Dallas, Texas, United States
  • Igarashi, Peter, University of Minnesota, Minneapolis, Minnesota, United States
Background

Autosomal dominant polycystic kidney disease (ADPKD) is primarily caused by mutations in PKD1 and PKD2. Mutations of PKD1 and PKD2 produce abnormalities in multiple intracellular signaling pathways, including activation of the mTOR pathway. Long noncoding RNAs (lncRNAs) are single-stranded RNA molecules over 200 nucleotides in length and lacking a long open-reading-frame. lncRNAs play important roles as epigenetic regulators of development and disease, but their involvement in PKD has not been previously described.

Methods

We have recently identified a kidney-specific lncRNA, called Hoxb3os, which is downregulated in kidney-specific Pkd1 and Pkd2 mutant mice and in cystic kidneys from ADPKD patients.

Results

Deletion of Hoxb3os in mIMCD3 mouse kidney epithelial cells resulted in activation of the mTOR pathway and increased oxidative phosphorylation (Aboudehen K, et al. J Biol Chem, 2018, in press). Consistent with activation of mTORC1 signaling, Hoxb3os-deficient cells displayed increased cell proliferation and defective autophagy. To identify the role of Hoxb3os in vivo, we used CRISPR-based gene editing to delete the genomic DNA encoding Hoxb3os in mouse zygotes. PCR analysis of genomic DNA and qRT-PCR analysis of kidney RNA demonstrated successful ablation of Hoxb3os in multiple independent founders. Mice lacking Hoxb3os were viable and had grossly normal kidney morphology up to age post-natal day P28. Immunoblot analysis of mutant kidney lysates showed increased phosphorylation of mTOR and downstream targets of mTORC1 but not mTORC2. Hoxb3os mutant kidneys also showed increased cell proliferation and defective autophagy. Co-immunoprecipitation experiments revealed that Hoxb3os was found in a complex with phosphorylated mTOR but not dephosphorylated mTOR in mouse kidney lysates.

Conclusion

Collectively, these findings identify Hoxb3os as a kidney-specific lncRNA that binds to mTORC1 and directly inhibits its downstream activity. Suppression of Hoxb3osmay contribute to the activation of the mTOR pathway in ADPKD, and restoration of Hoxb3osmay have therapeutic benefit.

Funding

  • NIDDK Support