Kidney Week

Abstract: PO1815

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

Session Information

• Hypertension and CVD: Mechanisms
  November 04, 2021 | Location: On-Demand, Virtual Only
  Abstract Time: 10:00 AM - 12:00 PM

Category: Hypertension and CVD

• 1403 Hypertension and CVD: Mechanisms

Authors

• Mukherji, Shreya T., Marshall Institute for Interdisciplinary Research, Huntington, West Virginia, United States

Shreya T. Mukherji, PhD

• Silva, Lilian, Marshall Institute for Interdisciplinary Research, Huntington, West Virginia, United States

Lilian Silva,

• Pierre, Sandrine V., Marshall Institute for Interdisciplinary Research, Huntington, West Virginia, United States

Sandrine V. Pierre,

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 α1^WT-expressing cells occurred. In mice, a SGLT2-Cre-driven KO and Rosa26 rescue system was used to selectively express WT NKA α1 (RPTα1^WT) or NKA α1Y260A (RPTα1^Y260A) 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 RPTα1^WT and RPTα1^Y260A mice. Kidney size, morphology, and overall structure assessed by periodic acid shift (PAS) staining was unchanged (n=3). In contrast, RPTα1^Y260A 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 RPTα1^Y260A mice was supported by a 50% increase in membrane abundance of NHE3 in female renal cortex compared to female RPTα1^WT, 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