title: Aldosterone signaling through transient receptor potential melastatin 7 cation channel (TRPM7) and its α-kinase domain.
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.
authors.affiliation: Kidney Research Centre, Dept. of Medicine, Ottawa Hospital Research Institute, University of Ottawa, Canada.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Yogi
authors.forename: Glaucia E
authors.initials: GE
authors.lastname: Callera
authors.forename: Sarah
authors.initials: S
authors.lastname: O'Connor
authors.forename: Tayze T
authors.initials: TT
authors.lastname: Antunes
authors.forename: William
authors.initials: W
authors.lastname: Valinsky
authors.forename: Perrine
authors.initials: P
authors.lastname: Miquel
authors.forename: Augusto C I
authors.initials: AC
authors.lastname: Montezano
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Perraud
authors.forename: Carsten
authors.initials: C
authors.lastname: Schmitz
authors.forename: Alvin
authors.initials: A
authors.lastname: Shrier
authors.forename: Rhian M
authors.initials: RM
authors.lastname: Touyz
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D000450:Aldosterone / Q000378:metabolism*; D017305:Annexin A1 / Q000378:metabolism; D001665:Binding Sites; D001896:Boron Compounds / Q000494:pharmacology; D002154:Calpain / Q000378:metabolism; D000077545:Eplerenone; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006801:Humans; D017136:Ion Transport; D008274:Magnesium / Q000378:metabolism*; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D011494:Protein Kinases / Q000172:deficiency / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction; D013049:Spectrin / Q000378:metabolism; D013148:Spironolactone / Q000031:analogs & derivatives / Q000494:pharmacology; D050053:TRPM Cation Channels / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism
chemical_list: D017305:Annexin A1; D001896:Boron Compounds; D017382:Reactive Oxygen Species; D050053:TRPM Cation Channels; D013049:Spectrin; D013148:Spironolactone; D000450:Aldosterone; D000077545:Eplerenone; D000255:Adenosine Triphosphate; C109986:2-aminoethoxydiphenyl borate; D019255:NADPH Oxidases; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; C486583:TRPM7 protein, human; D002154:Calpain; D008274:Magnesium
keywords: Aldosterone; Mg(2+); Signal transduction; TRPM7