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Kidney Week

Abstract: FR-PO560

Enhancing Intracellular Cholesterol Biosynthesis Slows PKD Progression

Session Information

Category: Genetic Diseases of the Kidneys

  • 1201 Genetic Diseases of the Kidneys: Cystic

Authors

  • Lakhia, Ronak, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
  • Biggers, Laurence Michael, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
  • Zumwalt, Maggie, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
  • Vale, Goncalo, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
  • McDonald, Jeff, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
Background

Metabolic reprogramming is a hallmark of ADPKD but remains incompletely understood. Cholesterol is a building block for cell membranes and functions in signaling pathways. Abnormal activation of cholesterol biosynthesis has been implicated in the pathogenesis of proliferative diseases such as cancer. However, the role of cholesterol biosynthesis in ADPKD is unknown.

Methods

We used transgenic mouse models to manipulate the activity of the transcriptional regulators of cholesterol/lipid synthesis: sterol regulatory element binding proteins (Srebp1/2). We inhibited cholesterol biosynthesis by deleting Scap in KsprtTA;TetOCre;Pkd1F/F; Pkhd1Cre;Pkd1F/F and Pkd1RC/RC mouse models. To enhance cholesterol biosynthesis we inactivated Insig1/2 in KsprtTA;TetOCre;Pkd1F/F; KspCre;Pkd1F/F and KspCre;Pkd1F/RC mouse models. Mice were sacrificed at pre-determined timepoints for histological and molecular analysis or monitored for survival. 3D cyst assay was performed on human ADPKD kidney cell lines treated with scramble or Insig1/2 siRNA. Western blot and sterolomics was completed on 10 and 18 day old KspCre;Pkd1F/RC and control mice kidneys to assess baseline Srebp1/2 activity and cholesterol levels.

Results

Total cholesterol was reduced in KspCre;Pkd1F/RC kidneys compared to controls. Western blot showed reduced nuclear Srebp2, the primary transcriptional driver of cholesterol synthesis, in early cystic KspCre;Pkd1F/RC kidneys. Inhibition of cholesterol synthesis (Scap deletion) increased kidney-weight/body-weight ratio and reduced kidney function in 3 mouse models of PKD. Conversely, augmentation of cholesterol synthesis pathway (knockout of Insig1/2) reduced kidney weight/body weight ratio reduced serum creatinine and prolonged survival in multiple mouse models of PKD. RNA-seq confirmed appropriate inhibition or activation of cholesterol biosynthesis pathway. Finally, Insig1/2 siRNA reduced cyst growth in 2 human ADPKD cell lines.

Conclusion

Srebp2 and cholesterol are reduced in Pkd1 mutant mice. Inhibition of cholesterol biosynthesis markedly aggravates cyst growth. Surprisingly, activation of cholesterol biosynthesis slows cyst growth in 3 mouse models of PKD and in human ADPKD cell lines. Further studies are needed to understand how enhancing intracellular cholesterol reduces PKD progression and determine if this pathway can be targeted therapeutically.

Funding

  • NIDDK Support