Aldosterone signaling through transient receptor potential melastatin 7 cation channel (TRPM7) and its α-kinase domain

Cell Signal. 2013 Nov;25(11):2163-75. doi: 10.1016/j.cellsig.2013.07.002. Epub 2013 Jul 6.

Abstract

We demonstrated a role for the Mg(2+) transporter TRPM7, a bifunctional protein with channel and α-kinase domains, in aldosterone signaling. Molecular mechanisms underlying this are elusive. Here we investigated the function of TRPM7 and its α-kinase domain on Mg(2+) and pro-inflammatory signaling by aldosterone. Kidney cells (HEK-293) expressing wild-type human TRPM7 (WThTRPM7) or constructs in which the α-kinase domain was deleted (ΔKinase) or rendered inactive with a point mutation in the ATP binding site of the α-kinase domain (K1648R) were studied. Aldosterone rapidly increased [Mg(2+)]i and stimulated NADPH oxidase-derived generation of reactive oxygen species (ROS) in WT hTRPM7 and TRPM7 kinase dead mutant cells. Translocation of annexin-1 and calpain-II and spectrin cleavage (calpain target) were increased by aldosterone in WT hTRPM7 cells but not in α-kinase-deficient cells. Aldosterone stimulated phosphorylation of MAP kinases and increased expression of pro-inflammatory mediators ICAM-1, Cox-2 and PAI-1 in Δkinase and K1648R cells, effects that were inhibited by eplerenone (mineralocorticoid receptor (MR) blocker). 2-APB, a TRPM7 channel inhibitor, abrogated aldosterone-induced Mg(2+) responses in WT hTRPM7 and mutant cells. In 2-APB-treated ΔKinase and K1648R cells, aldosterone-stimulated inflammatory responses were unchanged. These data indicate that aldosterone stimulates Mg(2+) influx and ROS production in a TRPM7-sensitive, kinase-insensitive manner, whereas activation of annexin-1 requires the TRPM7 kinase domain. Moreover TRPM7 α-kinase modulates inflammatory signaling by aldosterone in a TRPM7 channel/Mg(2+)-independent manner. Our findings identify novel mechanisms for non-genomic actions of aldosterone involving differential signaling through MR-activated TRPM7 channel and α-kinase.

Keywords: Aldosterone; Mg(2+); Signal transduction; TRPM7.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Adenosine Triphosphate / pharmacology
  • Aldosterone / metabolism*
  • Annexin A1 / metabolism
  • Binding Sites
  • Boron Compounds / pharmacology
  • Calpain / metabolism
  • Eplerenone
  • Gene Expression Regulation
  • HEK293 Cells
  • Humans
  • Ion Transport
  • Magnesium / metabolism*
  • NADPH Oxidases / genetics
  • NADPH Oxidases / metabolism
  • Phosphorylation
  • Protein Binding
  • Protein Kinases / deficiency
  • Protein Kinases / genetics*
  • Protein Structure, Tertiary
  • Protein-Serine-Threonine Kinases
  • Reactive Oxygen Species / metabolism
  • Signal Transduction*
  • Spectrin / metabolism
  • Spironolactone / analogs & derivatives
  • Spironolactone / pharmacology
  • TRPM Cation Channels / antagonists & inhibitors
  • TRPM Cation Channels / genetics*
  • TRPM Cation Channels / metabolism

Substances

  • Annexin A1
  • Boron Compounds
  • Reactive Oxygen Species
  • TRPM Cation Channels
  • Spectrin
  • Spironolactone
  • Aldosterone
  • Eplerenone
  • Adenosine Triphosphate
  • 2-aminoethoxydiphenyl borate
  • NADPH Oxidases
  • Protein Kinases
  • Protein-Serine-Threonine Kinases
  • TRPM7 protein, human
  • Calpain
  • Magnesium