WNK1 promotes PIP₂ synthesis to coordinate growth factor and GPCR-Gq signaling

Curr Biol. 2011 Dec 6;21(23):1979-87. doi: 10.1016/j.cub.2011.11.002. Epub 2011 Nov 23.

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism
  • DNA, Complementary / genetics
  • GTP-Binding Protein alpha Subunits, Gq-G11 / metabolism
  • Gene Knockdown Techniques
  • Green Fluorescent Proteins / metabolism
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Intercellular Signaling Peptides and Proteins / metabolism*
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Mice
  • Minor Histocompatibility Antigens
  • Models, Biological*
  • Oligonucleotides, Antisense / genetics
  • Patch-Clamp Techniques
  • Phosphatidylinositol 4,5-Diphosphate / biosynthesis*
  • Phospholipase C beta / metabolism*
  • Phosphotransferases (Alcohol Group Acceptor) / metabolism*
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • RNA, Small Interfering / genetics
  • Rats
  • Signal Transduction / genetics
  • Signal Transduction / physiology*
  • TRPC Cation Channels / metabolism
  • TRPC6 Cation Channel
  • WNK Lysine-Deficient Protein Kinase 1

Substances

  • DNA, Complementary
  • Intercellular Signaling Peptides and Proteins
  • Intracellular Signaling Peptides and Proteins
  • Minor Histocompatibility Antigens
  • Oligonucleotides, Antisense
  • Phosphatidylinositol 4,5-Diphosphate
  • RNA, Small Interfering
  • TRPC Cation Channels
  • TRPC6 Cation Channel
  • TRPC6 protein, human
  • Green Fluorescent Proteins
  • Phosphotransferases (Alcohol Group Acceptor)
  • phosphatidylinositol phosphate 4-kinase
  • Protein-Serine-Threonine Kinases
  • WNK Lysine-Deficient Protein Kinase 1
  • WNK1 protein, human
  • Phospholipase C beta
  • GTP-Binding Protein alpha Subunits, Gq-G11
  • Calcium