BACKGROUND: PLC-β signaling is generally thought to be mediated by allosteric activation by G proteins and Ca(2+). Although availability of the phosphatidylinositol-4,5-biphosphate (PIP(2)) substrate is limiting in some cases, its production has not been shown to be independently regulated as a signaling mechanism. WNK1 protein kinase is known to regulate ion homeostasis and cause hypertension when expression is increased by gene mutations. However, its signaling functions remain largely elusive. RESULTS: Using diacylglycerol-stimulated TRPC6 and inositol trisphosphate-mediated Ca(2+) transients as cellular biosensors, we show that WNK1 stimulates PLC-β signaling in cells by promoting the synthesis of PIP(2) via stimulation of phosphatidylinositol 4-kinase IIIα. WNK1 kinase activity is not required. Stimulation of PLC-β by WNK1 and by Gα(q) are synergistic; WNK1 activity is essential for regulation of PLC-β signaling by G(q)-coupled receptors, and basal input from G(q) is necessary for WNK1 signaling via PLC-β. WNK1 further amplifies PLC-β signaling when it is phosphorylated by Akt kinase in response to insulin-like growth factor. CONCLUSIONS: WNK1 is a novel regulator of PLC-β that acts by controlling substrate availability. WNK1 thereby coordinates signaling between G protein and Akt kinase pathways. Because PIP(2) is itself a signaling molecule, regulation of PIP(2) synthesis by WNK1 also allows the cell to initiate PLC signaling while independently controlling the effects of PIP(2) on other targets. These findings describe a new signaling pathway for Akt-activating growth factors, a mechanism for G protein-growth factor crosstalk, and a means to independently control PLC signaling and PIP(2) availability.
BACKGROUND:PLC-β signaling is generally thought to be mediated by allosteric activation by G proteins and Ca(2+). Although availability of the phosphatidylinositol-4,5-biphosphate (PIP(2)) substrate is limiting in some cases, its production has not been shown to be independently regulated as a signaling mechanism. WNK1 protein kinase is known to regulate ion homeostasis and cause hypertension when expression is increased by gene mutations. However, its signaling functions remain largely elusive. RESULTS: Using diacylglycerol-stimulated TRPC6 and inositol trisphosphate-mediated Ca(2+) transients as cellular biosensors, we show that WNK1 stimulates PLC-β signaling in cells by promoting the synthesis of PIP(2) via stimulation of phosphatidylinositol 4-kinase IIIα. WNK1 kinase activity is not required. Stimulation of PLC-β by WNK1 and by Gα(q) are synergistic; WNK1 activity is essential for regulation of PLC-β signaling by G(q)-coupled receptors, and basal input from G(q) is necessary for WNK1 signaling via PLC-β. WNK1 further amplifies PLC-β signaling when it is phosphorylated by Akt kinase in response to insulin-like growth factor. CONCLUSIONS:WNK1 is a novel regulator of PLC-β that acts by controlling substrate availability. WNK1 thereby coordinates signaling between G protein and Akt kinase pathways. Because PIP(2) is itself a signaling molecule, regulation of PIP(2) synthesis by WNK1 also allows the cell to initiate PLC signaling while independently controlling the effects of PIP(2) on other targets. These findings describe a new signaling pathway for Akt-activating growth factors, a mechanism for G protein-growth factor crosstalk, and a means to independently control PLC signaling and PIP(2) availability.
Authors: F H Wilson; S Disse-Nicodème; K A Choate; K Ishikawa; C Nelson-Williams; I Desitter; M Gunel; D V Milford; G W Lipkin; J M Achard; M P Feely; B Dussol; Y Berland; R J Unwin; H Mayan; D B Simon; Z Farfel; X Jeunemaitre; R P Lifton Journal: Science Date: 2001-08-10 Impact factor: 47.728
Authors: Ying Jie Wang; Jing Wang; Hui Qiao Sun; Manuel Martinez; Yu Xiao Sun; Eric Macia; Tomas Kirchhausen; Joseph P Albanesi; Michael G Roth; Helen L Yin Journal: Cell Date: 2003-08-08 Impact factor: 41.582
Authors: Alberto C Vitari; Maria Deak; Barry J Collins; Nick Morrice; Alan R Prescott; Anne Phelan; Sian Humphreys; Dario R Alessi Journal: Biochem J Date: 2004-02-15 Impact factor: 3.857
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Authors: Pedro San-Cristobal; Diana Pacheco-Alvarez; Ciaran Richardson; Aaron M Ring; Norma Vazquez; Fatema H Rafiqi; Divya Chari; Kristopher T Kahle; Qiang Leng; Norma A Bobadilla; Steven C Hebert; Dario R Alessi; Richard P Lifton; Gerardo Gamba Journal: Proc Natl Acad Sci U S A Date: 2009-02-24 Impact factor: 11.205
Authors: Samarpita Sengupta; Andrés Lorente-Rodríguez; Svetlana Earnest; Steve Stippec; Xiaofeng Guo; David C Trudgian; Hamid Mirzaei; Melanie H Cobb Journal: Proc Natl Acad Sci U S A Date: 2013-11-04 Impact factor: 11.205