Evidence for an association of prion protein and sphingolipid-mediated signaling

J Neurochem. 2008 Aug;106(3):1459-70. doi: 10.1111/j.1471-4159.2008.05498.x. Epub 2008 Jun 28.

Abstract

The physiological function of the cellular prion protein (PrP(c)) is unclear. PrP(c) associates with lipid rafts, highly glycolipid-rich membrane domains containing a large variety of signaling molecules, e.g., sphingolipids (SL). In this study, we investigated possible connections between PrP(c) and sphingolipid-associated signaling pathways. Using PrP(c)-wt and PrP(c)-k.o. hippocampal cell lines and mouse brains we showed higher activity of neutral and acid sphingomyelinase (SMase) in PrP(c)-k.o.-groups, while ceramide and sphingomyelin-levels were unchanged. Furthermore, despite lower basal expression levels of sphingosine kinase (SphK) in PrP(c)-k.o.-groups, the levels of its metabolite sphingosine-1-phosphate were increased, whereas S1P(3)-receptor expression was higher in PrP(c)-wt-groups again. In addition, we detected enhanced activity of phospholipase D1, an enzyme that seems to be suitable to act as a connector between the S1P(3) receptor and continuative signaling. Finally, evidence for an impact on downstream signaling cascades, especially activation of the PI3K/Akt pathway, was found. In summary, our data suggest that PrP(c) is involved in sphingolipid-associated signaling, modulating pathways that exert anti-apoptotic functions, hence indicating that PrP(c) plays a role in neuroprotection.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis Regulatory Proteins / physiology
  • Cell Survival / physiology
  • Cells, Cultured
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Neuroprotective Agents / metabolism
  • PrPC Proteins / genetics
  • PrPC Proteins / physiology*
  • Signal Transduction / physiology*
  • Sphingolipids / physiology*

Substances

  • Apoptosis Regulatory Proteins
  • Neuroprotective Agents
  • PrPC Proteins
  • Sphingolipids