title: Inorganic polyphosphate modulates TRPM8 channels.
abstract: Polyphosphate (polyP) is an inorganic polymer built of tens to hundreds of phosphates, linked by high-energy phosphoanhydride bonds. PolyP forms complexes and modulates activities of many proteins including ion channels. Here we investigated the role of polyP in the function of the transient receptor potential melastatin 8 (TRPM8) channel. Using whole-cell patch-clamp and fluorescent calcium measurements we demonstrate that enzymatic breakdown of polyP by exopolyphosphatase (scPPX1) inhibits channel activity in human embryonic kidney and F-11 neuronal cells expressing TRPM8. We demonstrate that the TRPM8 channel protein is associated with polyP. Furthermore, addition of scPPX1 altered the voltage-dependence and blocked the activity of the purified TRPM8 channels reconstituted into planar lipid bilayers, where the activity of the channel was initiated by cold and menthol in the presence of phosphatidylinositol 4,5-biphosphate (PtdIns(4,5)P(2)). The biochemical analysis of the TRPM8 protein also uncovered the presence of poly-(R)-3-hydroxybutyrate (PHB), which is frequently associated with polyP. We conclude that the TRPM8 protein forms a stable complex with polyP and its presence is essential for normal channel activity.
authors.affiliation: Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, New Jersey, United States of America.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Zakharian
authors.forename: Baskaran
authors.initials: B
authors.lastname: Thyagarajan
authors.forename: Robert J
authors.initials: RJ
authors.lastname: French
authors.forename: Evgeny
authors.initials: E
authors.lastname: Pavlov
authors.forename: Tibor
authors.initials: T
authors.lastname: Rohacs
mesh_terms: D017766:Acid Anhydride Hydrolases / Q000378:metabolism; D002460:Cell Line; D006801:Humans; D006885:Hydroxybutyrates / Q000378:metabolism; D011091:Polyesters / Q000378:metabolism; D011122:Polyphosphates / Q000494:pharmacology*; D000091402:Prohibitins; D011485:Protein Binding; D055550:Protein Stability; D050053:TRPM Cation Channels / Q000378:metabolism*; D000094122:Polyhydroxybutyrates
chemical_list: D017766:Acid Anhydride Hydrolases; D006885:Hydroxybutyrates; D011091:Polyesters; D011122:Polyphosphates; D000091402:Prohibitins; D050053:TRPM Cation Channels; C000717328:PHB protein, human; C425966:TRPM8 protein, human; C003182:poly-beta-hydroxybutyrate; D000094122:Polyhydroxybutyrates; C020137:exopolyphosphatase