title: Regulation of Mg2+ Reabsorption and Transient Receptor Potential Melastatin Type 6 Activity by cAMP Signaling.
abstract: The transient receptor potential melastatin type 6 (TRPM6) epithelial Mg(2+) channels participate in transcellular Mg(2+) transport in the kidney and intestine. Previous reports suggested a hormonal cAMP-dependent regulation of Mg(2+) reabsorption in the kidney. The molecular details of this process are, however, unknown. Adenylate cyclase 3 (Adcy3) has been shown to colocalize with the Na(+)/Cl(-) cotransporter, a marker of the distal convoluted segment of the kidney, the principal site of TRPM6 expression. Given the critical role of TRPM6 in Mg(2+) reabsorption, an inducible kidney-specific Adcy3 deletion mouse model was characterized for blood and urinary electrolyte disturbances under a normal--and low--Mg(2+) diet. Increased urinary Mg(2+) wasting and Trpm6 mRNA levels were observed in the urine and kidney of Adcy3-deleted animals compared with wild-type controls. Serum Mg(2+) concentration was significantly lower in Adcy3-deleted animals at day 7 on the low Mg(2+) diet. Using patch clamp electrophysiology, cell surface biotinylation, and total internal reflection fluorescence live cell imaging of transfected HEK293 cells, we demonstrated that cAMP signaling rapidly potentiates TRPM6 activity by promoting TRPM6 accumulation at the plasma membrane and increasing its single-channel conductance. Comparison of electrophysiological data from cells expressing the phosphorylation-deficient S1252A or phosphomimetic S1252D TRPM6 mutants suggests that phosphorylation at this intracellular residue participates in the observed stimulation of channel activity. Altogether, these data support a physiologically relevant magnesiotropic role of cAMP signaling in the kidney by a direct stimulatory action of protein kinase A on the plasma membrane trafficking and function of TRPM6 ion channels.
authors.affiliation: Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands;
authors.forename: Maxime G
authors.initials: MG
authors.lastname: Blanchard
authors.affiliation: Division of Nephrology.
authors.forename: Wararat
authors.initials: W
authors.lastname: Kittikulsuth
authors.affiliation: Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands; Center for Systems Biology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
authors.forename: Anil V
authors.initials: AV
authors.lastname: Nair
authors.affiliation: Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands;
authors.forename: Jeroen H F
authors.initials: JH
authors.lastname: de Baaij
authors.affiliation: Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands;
authors.forename: Femke
authors.initials: F
authors.lastname: Latta
authors.affiliation: Department of Pathology, School of Medicine, University of Utah, Salt Lake City, Utah; and.
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Genzen
authors.affiliation: Division of Nephrology.
authors.forename: Donald E
authors.initials: DE
authors.lastname: Kohan
authors.affiliation: Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands;
authors.forename: René J M
authors.initials: RJ
authors.lastname: Bindels
authors.affiliation: Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands; Joost.Hoenderop@radboudumc.nl.
authors.forename: Joost G J
authors.initials: JG
authors.lastname: Hoenderop
mesh_terms: D000262:Adenylyl Cyclases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D019921:Biotinylation; D002462:Cell Membrane / Q000378:metabolism; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D055724:Electrophysiological Phenomena; D057809:HEK293 Cells; D006801:Humans; D007668:Kidney / Q000378:metabolism*; D008274:Magnesium / Q000008:administration & dosage / Q000378:metabolism*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008856:Microscopy, Fluorescence; D010766:Phosphorylation; D012333:RNA, Messenger / Q000652:urine; D065608:Renal Reabsorption; D015398:Signal Transduction; D050053:TRPM Cation Channels / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D012333:RNA, Messenger; D050053:TRPM Cation Channels; C459082:TRPM6 protein, human; C530168:Trpm6 protein, mouse; D014665:Vasodilator Agents; D005576:Colforsin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D000262:Adenylyl Cyclases; C421784:adenylate cyclase 3; D008274:Magnesium
keywords: cAMP; cell and transport physiology; cell signaling; electrophysiology; ion channel; magnesium