Neuronal Orphan G-Protein Coupled Receptor Proteins Mediate Plasmalogens-Induced Activation of ERK and Akt Signaling

PLoS One. 2016 Mar 2;11(3):e0150846. doi: 10.1371/journal.pone.0150846. eCollection 2016.

Abstract

The special glycerophospholipids plasmalogens (Pls) are enriched in the brain and reported to prevent neuronal cell death by enhancing phosphorylation of Akt and ERK signaling in neuronal cells. Though the activation of Akt and ERK was found to be necessary for the neuronal cells survival, it was not known how Pls enhanced cellular signaling. To answer this question, we searched for neuronal specific orphan GPCR (G-protein coupled receptor) proteins, since these proteins were believed to play a role in cellular signal transduction through the lipid rafts, where both Pls and some GPCRs were found to be enriched. In the present study, pan GPCR inhibitor significantly reduced Pls-induced ERK signaling in neuronal cells, suggesting that Pls could activate GPCRs to induce signaling. We then checked mRNA expression of 19 orphan GPCRs and 10 of them were found to be highly expressed in neuronal cells. The knockdown of these 10 neuronal specific GPCRs by short hairpin (sh)-RNA lentiviral particles revealed that the Pls-mediated phosphorylation of ERK was inhibited in GPR1, GPR19, GPR21, GPR27 and GPR61 knockdown cells. We further found that the overexpression of these GPCRs enhanced Pls-mediated phosphorylation of ERK and Akt in cells. Most interestingly, the GPCRs-mediated cellular signaling was reduced significantly when the endogenous Pls were reduced. Our cumulative data, for the first time, suggest a possible mechanism for Pls-induced cellular signaling in the nervous system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Enzyme Activation
  • Extracellular Signal-Regulated MAP Kinases / metabolism*
  • Humans
  • MAP Kinase Signaling System
  • Mice
  • Neurons / metabolism*
  • Phosphorylation
  • Plasmalogens / metabolism*
  • Proto-Oncogene Proteins c-akt / metabolism*
  • Receptors, G-Protein-Coupled / metabolism*
  • Signal Transduction*

Substances

  • Plasmalogens
  • Receptors, G-Protein-Coupled
  • Proto-Oncogene Proteins c-akt
  • Extracellular Signal-Regulated MAP Kinases

Grants and funding

Japan Society for the Promotion of Science (JSPS) KAKENHI Grant Number 26460320 to TK. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.