Phosphatidylinositol 4,5-bisphosphate (PIP2) controls magnesium gatekeeper TRPM6 activity

• Published in: Scientific reports 2011-11, Vol.1 (1), p.146-146, Article 146
• Main Authors: Xie, Jia, Sun, Baonan, Du, Jianyang, Yang, Wenzhong, Chen, Hsiang-Chin, Overton, Jeffrey D., Runnels, Loren W., Yue, Lixia
• Format: Article
• Language: English
• Subjects: 631/154/436; 631/443; 631/45/269; 631/57; Amino Acid Sequence; Binding Sites; Cell Line; Channel gating; Depolarization; HEK293 Cells; Homeostasis; Hormones; Humanities and Social Sciences; Humans; Hydrolysis; Hypocalcemia; Hypomagnesemia; Ion Channel Gating; Kinetics; Magnesium; Magnesium - metabolism; Molecular Sequence Data; multidisciplinary; Mutant Proteins - genetics; Mutant Proteins - metabolism; Neutralization; Phosphatase; Phosphatidylinositol 4,5-diphosphate; Phosphatidylinositol 4,5-Diphosphate - metabolism; Protein Structure, Tertiary; Protein-Serine-Threonine Kinases; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Science; Sequence Homology, Amino Acid; Signal Transduction; Transient receptor potential proteins; Translocation; TRPM Cation Channels - antagonists & inhibitors; TRPM Cation Channels - genetics; TRPM Cation Channels - metabolism; Type C Phospholipases - metabolism
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep00146

TRPM6 is crucial for human Mg 2+ homeostasis as patients carrying TRPM6 mutations develop hypomagnesemia and secondary hypocalcemia (HSH). However, the activation mechanism of TRPM6 has remained unknown. Here we demonstrate that phosphatidylinositol-4,5-bisphophate (PIP 2 ) controls TRPM6 activation and Mg 2+ influx. Stimulation of PLC-coupled M1-receptors to deplete PIP 2 potently inactivates TRPM6. Translocation of over-expressed 5-phosphatase to cell membrane to specifically hydrolyze PIP 2 also completely inhibits TRPM6. Moreover, depolarization-induced-activation of the voltage-sensitive-phosphatase (Ci-VSP) simultaneously depletes PIP 2 and inhibits TRPM6. PLC-activation induced PIP 2 -depletion not only inhibits TRPM6, but also abolishes TRPM6-mediated Mg 2+ influx. Furthermore, neutralization of basic residues in the TRP domain leads to nonfunctional or dysfunctional mutants with reduced activity by PIP 2 , suggesting that they are likely to participate in interactions with PIP 2 . Our data indicate that PIP 2 is required for TRPM6 channel function; hydrolysis of PIP 2 by PLC-coupled hormones/agonists may constitute an important pathway for TRPM6 gating and perhaps Mg 2+ homeostasis.