Kidney Week

Abstract: TH-PO324

Single Tubule RNAseq From Gitelman Syndrome Mice Revealing Magnesium and Calcium Handling in Distal Renal Tubules

Session Information

• Fluid, Electrolyte, and Acid-Base Disorders: Basic
  November 03, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
  Abstract Time: 10:00 AM - 12:00 PM

Category: Fluid‚ Electrolyte‚ and Acid-Base Disorders

• 1001 Fluid‚ Electrolyte‚ and Acid-Base Disorders: Basic

Authors

• Sung, Chih-Chien, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan

Chih-Chien Sung,

• Hsu, Yu-Juei, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan

Yu-Juei Hsu,

• Lin, Chien-Ming, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan

Chien-Ming Lin,

• Lin, Shih-Hua P., Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan

Shih-Hua P. Lin,

Background

Gitelman syndrome (GS) is characterized by salt-losing hypotension, hypokalemic metabolic alkalosis, hypomagnesemia, and hypocalciuria caused by a specific mutation in the thiazide-sensitive sodium chloride co-transporter (NCC) gene Slc12a3. However, magnesium (Mg²⁺) and calcium (Ca²⁺) regulation associated gene in the distal renal tubules remains unclear.

Methods

We performed small samples RNA-seq from manual microdissection of distal convoluted tubules (DCTs) in nonsense Ncc Ser707X (S707X) homozygous knockin mice (NccS707X/S707X mice) (n=4) and wild type (WT, n=4). Cortical thick ascending limbs of Henle (cTALs), connecting tubule (CNT), cortical collecting duct (CCD) were also microdissected.

Results

Among DCT makers, Slc12a3 (NCC) and Pvalb (Parabumin) were significantly downregulated (Log₂TPM_S707X/WT: -4.45, P=0.0003; -6.888258295, P=0.0003, respectively). Mg²⁺ transporters of Trpm6, and Trpm7 gene expression were both significantly downregulated. Egf and Cnnm2 have been reported to increase TRPM6 trafficking or activity, were also decreased in DCT segment. Among Ca²⁺ transporter related genes, Trpv5 was only slightly increased, but other Atp2b4, Calb1 and Pvalb decreased in DCT. Claudins including Cldn10, Cldn16, and Cldn19, involving paracellularly reabsorption of Ca²⁺and Mg²⁺, were not changed in cTALs.

Conclusion

Our small samples RNA-Seq from dissected DCT highlight the possible molecular pathway of hypomagnesemia and hypocalciuria in GS. Inactivation of Slc12A3 gene may affect the DCT development causing loss of Mg²⁺ associated transporters. The pathogenesis of hypocalciuria is still complex and needs further experiments to explore.

Funding

• Government Support – Non-U.S.