title: Regulation of the transient receptor potential channel TRPM3 by phosphoinositides.
abstract: The transient receptor potential (TRP) channel TRPM3 is a calcium-permeable cation channel activated by heat and by the neurosteroid pregnenolone sulfate (PregS). TRPM3 is highly expressed in sensory neurons, where it plays a key role in heat sensing and inflammatory hyperalgesia, and in pancreatic β cells, where its activation enhances glucose-induced insulin release. However, despite its functional importance, little is known about the cellular mechanisms that regulate TRPM3 activity. Here, we provide evidence for a dynamic regulation of TRPM3 by membrane phosphatidylinositol phosphates (PIPs). Phosphatidylinositol 4,5-bisphosphate (PI[4,5]P2) and ATP applied to the intracellular side of excised membrane patches promote recovery of TRPM3 from desensitization. The stimulatory effect of cytosolic ATP on TRPM3 reflects activation of phosphatidylinositol kinases (PI-Ks), leading to resynthesis of PIPs in the plasma membrane. Various PIPs directly enhance TRPM3 activity in cell-free inside-out patches, with a potency order PI(3,4,5)P3 > PI(3,5)P2 > PI(4,5)P2 ≈ PI(3,4)P2 >> PI(4)P. Conversely, TRPM3 activity is rapidly and reversibly inhibited by activation of phosphatases that remove the 5-phosphate from PIPs. Finally, we show that recombinant TRPM3, as well as the endogenous TRPM3 in insuloma cells, is rapidly and reversibly inhibited by activation of phospholipase C-coupled muscarinic acetylcholine receptors. Our results reveal basic cellular mechanisms whereby membrane receptors can regulate TRPM3 activity.
authors.affiliation: Laboratory of Ion Channel Research and TRP Research Platform Leuven (TRPLe) and Laboratory of Obstetrics and Experimental Gynaecology, KU Leuven, 3000 Leuven, Belgium.
authors.forename: Balázs I
authors.initials: BI
authors.lastname: Tóth
authors.affiliation: Institut für Physiologie und Pathophysiologie, Philipps-Universität Marburg, 35037 Marburg, Germany.
authors.forename: Maik
authors.initials: M
authors.lastname: Konrad
authors.affiliation: Laboratory of Ion Channel Research and TRP Research Platform Leuven (TRPLe) and Laboratory of Obstetrics and Experimental Gynaecology, KU Leuven, 3000 Leuven, Belgium.
authors.forename: Debapriya
authors.initials: D
authors.lastname: Ghosh
authors.affiliation: Institut für Physiologie und Pathophysiologie, Philipps-Universität Marburg, 35037 Marburg, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Mohr
authors.affiliation: Institut für Physiologie und Pathophysiologie, Philipps-Universität Marburg, 35037 Marburg, Germany.
authors.forename: Christian R
authors.initials: CR
authors.lastname: Halaszovich
authors.affiliation: Institut für Physiologie und Pathophysiologie, Philipps-Universität Marburg, 35037 Marburg, Germany.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Leitner
authors.affiliation: Laboratory of Ion Channel Research and TRP Research Platform Leuven (TRPLe) and Laboratory of Obstetrics and Experimental Gynaecology, KU Leuven, 3000 Leuven, Belgium Laboratory of Ion Channel Research and TRP Research Platform Leuven (TRPLe) and Laboratory of Obstetrics and Experimental Gynaecology, KU Leuven, 3000 Leuven, Belgium.
authors.forename: Joris
authors.initials: J
authors.lastname: Vriens
authors.affiliation: Institut für Physiologie und Pathophysiologie, Philipps-Universität Marburg, 35037 Marburg, Germany thomas.voets@med.kuleuven.be johannes.oberwinkler@uni-marburg.de.
authors.forename: Johannes
authors.initials: J
authors.lastname: Oberwinkler
authors.affiliation: Laboratory of Ion Channel Research and TRP Research Platform Leuven (TRPLe) and Laboratory of Obstetrics and Experimental Gynaecology, KU Leuven, 3000 Leuven, Belgium thomas.voets@med.kuleuven.be johannes.oberwinkler@uni-marburg.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Voets
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D006930:Hyperalgesia / Q000378:metabolism; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D011284:Pregnenolone / Q000378:metabolism; D011984:Sensory Receptor Cells / Q000378:metabolism; D050053:TRPM Cation Channels / Q000378:metabolism*
chemical_list: D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols; D050053:TRPM Cation Channels; C475667:TRPM3 protein, human; C018370:pregnenolone sulfate; D011284:Pregnenolone; D000255:Adenosine Triphosphate; D010744:Phosphoric Monoester Hydrolases