Elucidation of the Distal Convoluted Tubule Transcriptome Identifies New Candidate Genes Involved in Renal Mg(2+) Handling

Am J Physiol Renal Physiol. 2013 Dec 1;305(11):F1563-73. doi: 10.1152/ajprenal.00322.2013. Epub 2013 Oct 2.

Abstract

The kidney plays a key role in the maintenance of Mg(2+) homeostasis. Specifically, the distal convoluted tubule (DCT) is instrumental in the fine-tuning of renal Mg(2+) handling. In recent years, hereditary Mg(2+) transport disorders have helped to identify important players in DCT Mg(2+) homeostasis. Nevertheless, several proteins involved in DCT-mediated Mg(2+) reabsorption remain to be discovered, and a full expression profile of this complex nephron segment may facilitate the discovery of new Mg(2+)-related genes. Here, we report Mg(2+)-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 Mg(2+)-deficient or Mg(2+)-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 Mg(2+) to identify Mg(2+) 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 Mg(2+). Moreover, new genes were identified that are potentially involved in renal Mg(2+) handling. To confirm that the selected candidate genes were regulated by dietary Mg(2+) 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 Mg(2+)-deficient diet. By elucidating the Mg(2+)-sensitive DCT transcriptome, new candidate genes in renal Mg(2+) handling have been identified.

Keywords: Complex Object Parametric Analyzer and Sorter; distal convoluted tubule; gene expression microarray; hypomagnesemia; magnesium homeostasis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Transport / genetics*
  • Carrier Proteins / metabolism
  • Homeostasis / physiology*
  • Kidney Tubules, Distal / metabolism*
  • Magnesium / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Nephrons / metabolism
  • Transcriptome* / genetics

Substances

  • Carrier Proteins
  • Magnesium