#2640 SINGLE TUBULE RNASEQ FROM GITLEMAN SYNDROME MICE REVEALING MAGNESIUM HANDLING IN DISTAL RENAL TUBULES

Abstract

Abstract Background and Aims 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+) associated gene in the distal renal tubules remains unclear. Method We performed small samples RNA-seq from manual microdissection of distal convoluted tubules (DCT1s) 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 (Log2TPMS707X/WT: −4.45, P = 0.0003; −6.888258295, P = 0.0003, respectively). Mg2+ transporters of Trpm6 gene expression were significantly downregulated. In addition, Egf and Cnnm2 have been reported to increase TRPM6 trafficking or activity, were also decreased in DCT segment. Rack1 was also decreased in DCT1. Claudins including Cldn10, Cldn16, and Cldn19, involving paracellularly reabsorption of Ca2+and Mg2+, were not changed in cTALs. All findings indicate chronic hypokalemia may mediate DCT1 remodeling and affect development. Conclusion Our small samples RNA-Seq from dissected DCT highlight the possible molecular pathway of hypomagnesemia in GS. Chronic hypokalemia caused by inactivation of Slc12A3 gene may affect the DCT development causing loss of Mg2+ associated transporters.