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Abstract: PO1815

Renal Proximal Tubule-Specific Alteration of the NKA/Src Receptor Complex in the Mouse: Evidence for Sexual Dimorphism

Session Information

Category: Hypertension and CVD

  • 1403 Hypertension and CVD: Mechanisms

Authors

  • Mukherji, Shreya T., Marshall Institute for Interdisciplinary Research, Huntington, West Virginia, United States
  • Silva, Lilian, Marshall Institute for Interdisciplinary Research, Huntington, West Virginia, United States
  • Pierre, Sandrine V., Marshall Institute for Interdisciplinary Research, Huntington, West Virginia, United States
Background

The Na+/K+-ATPase (NKA) expressed on the basolateral membrane of renal proximal tubule (RPT) cells serves an anti-natriuretic enzymatic function through its classically recognized ion-pumping properties. There is also pharmacological evidence that, through a Src-mediated mechanism, Na/K-ATPase α1 serves a counteracting natriuretic receptor function that reduces NKA- and NHE3-mediated transport, leading to decreased transepithelial Na+ flux.

Methods

To test this genetically, we generated RPT cells and mice expressing wild-type (WT) or Src signaling null mutant (Y260A) forms of NKA α1, both with intact ion-transporting functions. In porcine RPT cells (LLC-PK1) expressing NKA α1 Y260A, a 50% decrease in phosphorylation-mediated inactivation of NHE3 compared to WT NKA α1WT-expressing cells occurred. In mice, a SGLT2-Cre-driven KO and Rosa26 rescue system was used to selectively express WT NKA α1 (RPTα1WT) or NKA α1Y260A (RPTα1Y260A) in the RPT. For all renal phenotyping and biochemical assessments, we studied 4-month adult mice. Basal and renal characterization was conducted by metabolic cages, lithium clearance, and urine analysis.

Results

The RPT-specific rescue was confirmed by immunohistochemistry in kidney cross-sections from RPTα1WT and RPTα1Y260A mice. Kidney size, morphology, and overall structure assessed by periodic acid shift (PAS) staining was unchanged (n=3). In contrast, RPTα1Y260A mice presented with a RPT-mediated hyper-reabsorptive phenotype of 60% decrease in total daily urine output and 40% decrease in absolute sodium output in females but not in males (n=6-11). This sexual dimorphism in urinary phenotype of RPTα1Y260A mice was supported by a 50% increase in membrane abundance of NHE3 in female renal cortex compared to female RPTα1WT, which was not observed in males (n=4-5).

Conclusion

These observations are compatible with a sexual dimorphism in the NKA/Src mechanism of regulation of NHE3 and Na+ transport in the RPT. This study highlights the importance of improving our understanding of the natriuretic mechanism of NKA signaling in the RPT and its potential impact on sex-based differences in renal physiology and pathophysiology.

Funding

  • Private Foundation Support