Kidney Week

Abstract: FR-PO777

Caloric Restriction During Pregnancy Reduces Nephron Endowment and Impairs Adult Kidney Function by Inactivating mTOR and the Methionine Salvage Pathway

Session Information

• Development and Organoid Models
  November 08, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Development, Stem Cells, and Regenerative Medicine

• 500 Development, Stem Cells, and Regenerative Medicine

Authors

• Volovelsky, Oded, Hadassah Hebrew University Medical Center, Jerusalem, Israel

Oded Volovelsky,

• Resnick, Elad, Hadassah Medical Center, Jerusalem, Israel

Elad Resnick,

• Hinden, Liad, The Hebrew University of Jerusalem, Jerusalem, Israel

Liad Hinden,

• Tam, Joseph, The Hebrew University of Jerusalem, Jerusalem, Israel

Joseph Tam,

• Kopan, Raphael, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States

Raphael Kopan,

• Nechama, Morris, Hadassah Medical Center, Jerusalem, Israel

Morris Nechama,

Background

Maternal malnutrition during pregnancy correlates with lower nephron numbers and higher risk of chronic kidney disease (CKD) in adulthood, but the underlying molecular mechanisms are still unknown. The nephron progenitor pool exhausts abruptly in third postpartum day in mice with no nephrogenesis at later stages. We used a mouse model to study the effects of maternal caloric restriction on kidney development and nephron progenitor cells (NPCs).

Methods

Pregnant CD1 mice were monitored in metabolic cages and their daily caloric intake was reduced by 30% compared to the average consumption of the control group at the same gestational age. The effect on kidney morphology and function was measured by immunostaining, kidney biomarkers analysis and nephron count. Six2⁺ GFP⁺ NPCs were extracted from Six2 Cre^tg/+ E18.5 embryos of calorically restricted pregnant dams or controls and isolated by FACS. mRNA expression and metabolomic activity in sorted NPCs were evaluated by bulk RNAseq and mass spectrometry, respectively. Key findings were validated using western blotting.

Results

Animals exposed to caloric restriction in utero had 50% fewer nephrons after birth and throughout adulthood as well as lower kidney function, as demonstrated by higher serum urea levels. Nephrogenesis was shorter by at least 24 hours. Calorically restricted E18.5 Six2⁺ NPCs had decreased expression of mTOR pathway genes, and lower overall mTOR activity, reflected in lower levels of phosphorylated ribosomal protein S6. Mass spectrometry of metabolites from isolated NPCs identified a strong reduction in the methionine salvage pathway.

Conclusion

Reduced mTOR signalling and methionine salvage activity in NPCs from fetuses carried by malnourished mothers led to a premature end of nephrogenesis, reduced nephron numbers, and the associated increased risk for CKD in adulthood.

Funding

• Government Support - Non-U.S.