title: WNK1 promotes PIP₂ synthesis to coordinate growth factor and GPCR-Gq signaling.
abstract: 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: Department of Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
authors: Sung-Wan
authors: SW
authors: An
authors: Seung-Kuy
authors: SK
authors: Cha
authors: Joonho
authors: J
authors: Yoon
authors: Seungwoo
authors: S
authors: Chang
authors: Elliott M
authors: EM
authors: Ross
authors: Chou-Long
authors: CL
authors: Huang
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000378:metabolism; D055785:Gene Knockdown Techniques; D049452:Green Fluorescent Proteins / Q000378:metabolism; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D015778:Minor Histocompatibility Antigens; D008954:Models, Biological; D016376:Oligonucleotides, Antisense / Q000235:genetics; D018408:Patch-Clamp Techniques; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000096:biosynthesis*; D054799:Phospholipase C beta / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D050052:TRPC Cation Channels / Q000378:metabolism; D000074287:TRPC6 Cation Channel; D000076204:WNK Lysine-Deficient Protein Kinase 1
chemical_list: D018076:DNA, Complementary; D036341:Intercellular Signaling Peptides and Proteins; D047908:Intracellular Signaling Peptides and Proteins; D015778:Minor Histocompatibility Antigens; D016376:Oligonucleotides, Antisense; D019269:Phosphatidylinositol 4,5-Diphosphate; D034741:RNA, Small Interfering; D050052:TRPC Cation Channels; D000074287:TRPC6 Cation Channel; C117032:TRPC6 protein, human; D049452:Green Fluorescent Proteins; D017853:Phosphotransferases (Alcohol Group Acceptor); C402182:phosphatidylinositol phosphate 4-kinase; D017346:Protein Serine-Threonine Kinases; D000076204:WNK Lysine-Deficient Protein Kinase 1; C498743:WNK1 protein, human; D054799:Phospholipase C beta; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D002118:Calcium