ASN's Mission

To create a world without kidney diseases, the ASN Alliance for Kidney Health elevates care by educating and informing, driving breakthroughs and innovation, and advocating for policies that create transformative changes in kidney medicine throughout the world.

learn more

Contact ASN

1401 H St, NW, Ste 900, Washington, DC 20005

email@asn-online.org

202-640-4660

The Latest on X

Kidney Week

Please note that you are viewing an archived section from 2021 and some content may be unavailable. To unlock all content for 2021, please visit the archives.

Abstract: PO1088

SALL3 Is a Salt-Responsive Distal Convoluted Tubule-Specific Transcription Factor Induced in Distal Nephron Remodeling

Session Information

Category: Fluid, Electrolyte, and Acid-Base Disorders

  • 901 Fluid, Electrolyte, and Acid-Base Disorders: Basic

Authors

  • Jung, Hyun Jun, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
  • Delpire, Eric J., Vanderbilt University Medical Center, Nashville, Tennessee, United States
  • Welling, Paul A., Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
Background

Adaptive remodeling of the distal nephron provides a physiological mechanism to control electrolyte transport and body fluid homeostasis. Activation of the sodium chloride cotransporter (NCC, Slc12a3) in the DCT is paralleled by an increase in DCT mass as an adaptive response to intravascular volume depletion or hypokalemia. The downstream regulatory factors that induce structural expansion of DCT are unknown.

Methods

Mice were genetically engineered to constitutively activate the SPAK kinase (CA-SPAK) in the DCT, causing constitutive NCC activation, and DCT hypertrophy and hyperplasia. Genome-wide RNA-Seq transcriptomic analysis was performed in renal cortical tissue. Differential gene expression analysis was performed to compare 1) CA-SPAK vs wild type (WT-CT) on control diet and 2) CA-SPAK on high salt diet (CS-HS) and WT on high salt diet (WT-HS). Bioinformatic approaches were applied to identify the DCT-specific transcription factors (TFs) that are dependent on the NCC activation. TF protein localization and expression was evaluated by immunofluorescence and confocal microscopy, and image analysis tools.

Results

Differential expression analysis and cell deconvolution of the bulk RNA-Seq, using kidney single-cell transcriptome datasets, revealed 10 TFs (Camta1, Emx1, Hoxd8, Hoxd9, Hoxd10, Tfap2b, Tfcp2l1, Tsc22d2, Sall3 and Zfp467) that were significantly induced in DCT of the CA-SPAK mice with high salt diet. Among 10 TF candidates, Spalt like transcription factor 3 (Sall3) was the only DCT-specific TF that was induced by CA-SPAK, and further increased by high salt diet. Network analysis revealed that Sall3 interacts with eight of the other induced TFs (Emx1, Hoxd10, Tfcp2l1, Hoxd9, Hoxd8, Camta1, Tfap2b and Zfp467). Microscopy confirmed Sall3 is specifically expressed in DCT cells, where it localizes predominately to the nucleus and is significantly increased in the CA-SPAK mice, and increased further upon dietary salt loading.

Conclusion

In summary, Sall3 is the predominate DCT-specific TF that is activated during DCT expansion, suggesting that it is a key component of the core transcriptional regulatory circuit maintaining DCT cell identity as the DCT expands.

Funding

  • Private Foundation Support