A neurotoxic glycerophosphocholine impacts PtdIns-4, 5-bisphosphate and TORC2 signaling by altering ceramide biosynthesis in yeast

PLoS Genet. 2014 Jan;10(1):e1004010. doi: 10.1371/journal.pgen.1004010. Epub 2014 Jan 23.

Abstract

Unbiased lipidomic approaches have identified impairments in glycerophosphocholine second messenger metabolism in patients with Alzheimer's disease. Specifically, we have shown that amyloid-β42 signals the intraneuronal accumulation of PC(O-16:0/2:0) which is associated with neurotoxicity. Similar to neuronal cells, intracellular accumulation of PC(O-16:0/2:0) is also toxic to Saccharomyces cerevisiae, making yeast an excellent model to decipher the pathological effects of this lipid. We previously reported that phospholipase D, a phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P2)-binding protein, was relocalized in response to PC(O-16:0/2:0), suggesting that this neurotoxic lipid may remodel lipid signaling networks. Here we show that PC(O-16:0/2:0) regulates the distribution of the PtdIns(4)P 5-kinase Mss4 and its product PtdIns(4,5)P2 leading to the formation of invaginations at the plasma membrane (PM). We further demonstrate that the effects of PC(O-16:0/2:0) on the distribution of PM PtdIns(4,5)P2 pools are in part mediated by changes in the biosynthesis of long chain bases (LCBs) and ceramides. A combination of genetic, biochemical and cell imaging approaches revealed that PC(O-16:0/2:0) is also a potent inhibitor of signaling through the Target of rampamycin complex 2 (TORC2). Together, these data provide mechanistic insight into how specific disruptions in phosphocholine second messenger metabolism associated with Alzheimer's disease may trigger larger network-wide disruptions in ceramide and phosphoinositide second messenger biosynthesis and signaling which have been previously implicated in disease progression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alzheimer Disease / etiology
  • Alzheimer Disease / metabolism*
  • Alzheimer Disease / pathology
  • Amyloid beta-Peptides / metabolism
  • Cell Membrane / drug effects
  • Ceramides / biosynthesis
  • Humans
  • Mechanistic Target of Rapamycin Complex 2
  • Multiprotein Complexes / biosynthesis
  • Multiprotein Complexes / metabolism*
  • Neurons / drug effects
  • Phosphatidylinositol 4,5-Diphosphate / metabolism*
  • Phosphorylcholine / toxicity*
  • Phosphotransferases (Alcohol Group Acceptor) / biosynthesis
  • Saccharomyces cerevisiae
  • Saccharomyces cerevisiae Proteins / biosynthesis
  • Signal Transduction / drug effects
  • TOR Serine-Threonine Kinases / biosynthesis
  • TOR Serine-Threonine Kinases / metabolism*

Substances

  • Amyloid beta-Peptides
  • Ceramides
  • Multiprotein Complexes
  • Phosphatidylinositol 4,5-Diphosphate
  • Saccharomyces cerevisiae Proteins
  • Phosphorylcholine
  • Phosphotransferases (Alcohol Group Acceptor)
  • MSS4 protein, S cerevisiae
  • Mechanistic Target of Rapamycin Complex 2
  • TOR Serine-Threonine Kinases