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Abstract: TH-OR36

Arginine Metabolism Has a Pivotal Role in Cystogenesis of Tuberous Sclerosis Complex (TSC) and Its Inhibition Alleviates TSC Cyst Overload

Session Information

Category: Genetic Diseases of the Kidneys

  • 1101 Genetic Diseases of the Kidneys: Cystic

Authors

  • Nechama, Morris, Hadassah University Medical Center, Jerusalem, Israel
  • Amleh, Athar, Hadassah University Medical Center, Jerusalem, Israel
  • Ben-Dov, Iddo Z., Hadassah University Medical Center, Jerusalem, Israel
  • Volovelsky, Oded, Hadassah University Medical Center, Jerusalem, Israel
Background

Kidney disease affects most patients with tuberous sclerosis complex disease (TSC) and is a leading cause of death in adulthood. Mutations in Tsc1 or Tsc2 in TSC induce mTOR activation, resulting in cell growth manifested by cystic kidney disease. However, the exact mechanisms leading to tubular cell damage and cyst formation remain poorly understood. Metabolic reprogramming is an essential mechanism by which cells rewire their activity to promote cell proliferation and growth. Here, we show that TSC kidneys exhibit major metabolic alterations, mainly the arginine biosynthesis pathway and that arginine pathway inhibition alleviates the TSC cyst overload.

Methods

Metabolites were extracted and analyzed from kidneys of vehicle or rapamycin-treated Six2 Cre+/tg Tsc1-/-, and control mice using liquid chromatography/inline tandem mass spectrometry. Kidneys were also used for histology, RNA/protein extraction, and immunofluorescence.

Results

Metabolome analysis of whole kidneys and proximal tubular cells (PTCs) from TSC mice showed major perturbation in several metabolic pathways, mainly the arginine biosynthesis pathway. These trends were associated with an increase in urea cycle metabolites and the rate-limiting enzyme, argininosuccinate synthase 1 (ASS1), expression levels. High ASS1 level was specifically localized in cyst lining cells in the TSC kidney. Rapamycin treatment reversed the increase in ASS1 expression in Tsc1 Knockout HK2 cell, emphasizing the contribution of the Tsc1-mTORC1 pathway to ASS1 expression. Finally, arginine depletion in vivo and in vitro reduced the mTOR signaling pathway, cell proliferation, and kidney cyst overload.

Conclusion

TSC kidneys exhibit significant perturbations in the arginine biosynthesis pathway. Based on our results, we suggest that dysregulated mTOR pathway in TSC PTCs induces the arginine biosynthesis pathway by overexpression of ASS1 to support the high arginine demand in PTCs. Arginine depletion ameliorates PTC signaling and cell proliferation which are significant contributors to cyst development in TSC. Our studies highlight potential targets for immediate translational and clinical implications.