Kidney Week

Abstract: TH-OR56

Spalt-Like Transcription Factor 3 (Sall3) Is Essential for Maintaining Distal Convoluted Tubule Differentiation

Session Information

• Fluid, Electrolyte, and Acid-Base Disorders: Back to the Basics
  October 24, 2024 | Location: Room 4, Convention Center
  Abstract Time: 04:40 PM - 04:50 PM

Category: Fluid, Electrolytes, and Acid-Base Disorders

• 1101 Fluid, Electrolyte, and Acid-Base Disorders: Basic

Authors

• Jung, Hyun Jun, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States

Hyun Jun Jung, PhD

• Kim, Boyoung, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States

Boyoung Kim

• Ferdaus, Mohammed Zubaerul, Vanderbilt University Medical Center, Nashville, Tennessee, United States

Mohammed Zubaerul Ferdaus, PhD

• Al-Qusairi, Lama, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States

Lama Al-Qusairi, PhD

• Grimm, Rick, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States

Rick Grimm, PhD

• Delpire, Eric J., Vanderbilt University Medical Center, Nashville, Tennessee, United States

Eric J. Delpire, PhD

• Welling, Paul A., The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States

Paul A. Welling, MD

Background

Activation of the sodium chloride cotransporter (NCC) in the distal convoluted tubule (DCT) by the WNK-SPAK signaling pathway is paralleled by an adaptive remodeling process, characterized by DCT cell proliferation and hypertrophy. Regulatory networks responsible for remodeling and maintaining DCT fate have not been identified. Here we identify a DCT-specific transcription factor (TF), Sall3, that is rapidly induced by SPAK-dependent signaling, and characterize the consequences of conditionally and specifically deleting Sall3 from the DCT.

Methods

Genome-wide single-nucleus and bulk RNA sequencing (RNA-Seq) was performed in the kidney tissues of wild-type (WT) mice and mice genetically engineered to constitutively activate the SPAK kinase (CA-SPAK) in the DCT, causing constitutive NCC activation. Multimodal-bioinformatic analyses were used to identify the DCT-specific TFs that are induced downstream of SPAK-NCC. An inducible DCT-specific knockout (KO) mouse model was generated for one of the SPAK-induced TFs, Sall3, and the phenotype of the mice was characterized.

Results

RNA-Seq and bioinformatic analysis of WT and CA-SPAK mouse kidneys identified Sall3 as a key DCT TF that was significantly induced by chronic SPAK-NCC activation in the DCT. Immunolabeling confirmed that Sall3 is primarily expressed in DCT cell nuclei, and supported snRNA-Seq that Sall3 is also expressed in a minority population of AQP2-negative CNT cells. In the CA-SPAK mice, SALL3 protein abundance only significantly increased in the DCT nuclei. A similar response was observed in WT mice when WNK-SPAK was physiologically activated with low K diet. Induction of DCT-specific Sall3 KO significantly reduced the expression of DCT-specific genes, indicative of loss of DCT patterning.

Conclusion

In summary, Sall3 is a key component of the core transcriptional regulatory circuit that maintains DCT cell identity in the basal state and as the tubule expands.

Funding

• NIDDK Support