Renal Physiology

Elucidation of the distal convoluted tubule transcriptome identifies new candidate genes involved in renal Mg2+ handling

Jeroen H. F. de Baaij, Marian J. Groot Koerkamp, Marla Lavrijsen, Femke van Zeeland, Hans Meijer, Frank C. P. Holstege, René J. M. Bindels, Joost G. J. Hoenderop


The kidney plays a key role in the maintenance of Mg2+ homeostasis. Specifically, the distal convoluted tubule (DCT) is instrumental in the fine-tuning of renal Mg2+ handling. In recent years, hereditary Mg2+ transport disorders have helped to identify important players in DCT Mg2+ homeostasis. Nevertheless, several proteins involved in DCT-mediated Mg2+ reabsorption remain to be discovered, and a full expression profile of this complex nephron segment may facilitate the discovery of new Mg2+-related genes. Here, we report Mg2+-sensitive expression of the DCT transcriptome. To this end, transgenic mice expressing enhanced green fluorescent protein under a DCT-specific parvalbumin promoter were subjected to Mg2+-deficient or Mg2+-enriched diets. Subsequently, the Complex Object Parametric Analyzer and Sorter allowed, for the first time, isolation of enhanced green fluorescent protein-positive DCT cells. RNA extracts thereof were analyzed by DNA microarrays comparing high versus low Mg2+ to identify Mg2+ regulatory genes. Based on statistical significance and a fold change of at least 2, 46 genes showed differential expression. Several known magnesiotropic genes, such as transient receptor potential cation channel, subfamily M, member 6 (Trpm6), and Parvalbumin, were upregulated under low dietary Mg2+. Moreover, new genes were identified that are potentially involved in renal Mg2+ handling. To confirm that the selected candidate genes were regulated by dietary Mg2+ availability, the expression levels of solute carrier family 41, member 3 (Slc41a3), pterin-4 α-carbinolamine dehydratase/dimerization cofactor of hepatocyte nuclear factor-1α (Pcbd1), TBC1 domain family, member 4 (Tbc1d4), and uromodulin (Umod) were determined by RT-PCR analysis. Indeed, all four genes show significant upregulation in the DCT of mice fed a Mg2+-deficient diet. By elucidating the Mg2+-sensitive DCT transcriptome, new candidate genes in renal Mg2+ handling have been identified.

  • magnesium homeostasis
  • hypomagnesemia
  • gene expression microarray
  • Complex Object Parametric Analyzer and Sorter
  • distal convoluted tubule


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